Volume 5/ Issue 2/ August 2018

Temperature regulators adjust the flow of steam or liquids to control the temperature of a fluid in heating or cooling equipment. Typical applications include:
• Large storage tanks that change temperature gradually
• Shell and tube heaters that require instant response
• Steam tables
• Oil preheaters
• Sterilizing equipment
• Textile dryers
• Processing equipment.
• Cooling equipment

For effective temperature control, you need to choose the right regulator, correctly size the valve, and properly locate and install the regulator. For the best steam heating system performance, you also need proper trap sizing, location and installation.

All temperature regulators include a valve (body) and a sensor (actuator). The actuator unit’s bulb must be fully immersed in the fluid where temperature is to be controlled. Regulator bulbs are filled with a fluid that expands with heat, enabling the valve to increase or reduce the flow of the heating media in proportion to the sensed temperature deviation.

Series 1140 and 1141 self-actuated vapor-pressure type temperature regulators

Series 1140 and 1141 self-actuated vapor-pressure type temperature regulators:
• Regulate the flow of liquid or steam through a valve to maintain a set temperature in the controlled fluid.
• Consist of a valve body and an actuator/sensing unit.
• Have an attached “superstructure” that consists of a valve bracket, adjustment spring, upper stem and
temperature adjustment wheel.
• Can be used in heating, cooling or mixing / diverting, depending on valve materials and internal valve
configurations. For example, valves with stainless steel discs generally can withstand higher pressure
differentials than valves with composition discs. Heating or cooling applications typically require
two-port valve bodies, while mixing / diverting uses three-port bodies.
• Are self-sensing and self-actuating, requiring no auxiliary power source to operate the valve or detect a temperature change in the medium (fluid) whose temperature is being controlled.

The sensing units (actuators) have:
• Sensing bulbs that must be fully immersed in the fluid where temperature is to be controlled.
• Sensing bulbs filled under vacuum with a volatile fluid.
• An armored capillary tube that carries the volatile fluid from the sensing bulb to a bellows that
operates the valve.
• Bellows that:
– Are compressed by the vacuum in the sensing bulb and capillary tube when the sensing bulb is cold.
–  Expand with rising vapor pressure when the volatile fluid vaporizes as the sensed temperature increases.
–  Amplify the force of the vapor pressure, generating thrust to overcome the adjusting spring and push
on the valve upper stem. The over-balancing of the spring force by the bellows moves the valve stem.

You can manually operate the adjustment wheel to vary the spring compression, setting the valve to close at any point in the sensing bulb’s temperature range. For best results, the temperature set point should be in the upper half of the temperature range.

In a heating regulator, a direct acting valve seat is:
• Held open by the adjustment spring.
• Closed by the movement of the bellows on the valve stem.

When the volatile fluid is below its saturation temperature, the vacuum inside the bulb pulls the bellows away from the valve stem. As the volatile fluid’s temperature increases, the expanding bellows close the valve, shutting off the flow of steam or other heating medium to the heat exchanger.

For cooling applications, the reverse acting valve seat is:
• Held closed by the adjustment spring.
• Opened by movement of the bellows on the valve stem.

An increase in the volatile fluid’s temperature causes the expanding bellows to open the valve, allowing more water or other cooling medium to flow to and through the heat exchanger.

In mixing / diverting water systems, the valve body has three ports. The actuator bellows control the
position of a valve piston.
• In a mixing valve, the piston position determines how much hot water from one side port is mixed
with cold water from the other side port. The blended temperature combination exits via the valve’s
third, or bottom, port.
• In a diverting valve, fluid enters from the valve’s bottom port. The piston position determines
how much water exits via the two side ports. When the medium temperature is below the actuator
temperature range, all fluid exits one side port. When the medium temperature is above the set
point, all fluid exits the other side port. As the valve modulates within the actuator’s control
range, fluid discharges from both side openings.

Fluids with various boiling points are used to achieve varying actuator/sensor control temperature ranges. Series 1140 and 1141 temperature regulators offer eight temperature range actuators from 40ºF to 220ºF (4.4ºC to 104ºC). Each temperature range actuator provides 40ºF (4ºC) temperature adjustment.

Series 1140/1141 offers 5 body styles:
• Single and double seats for heating and cooling – 3-valve bodies with stainless steel seats and trim
• Sliding piston for mixing / diverting
• Brass or iron bodies, depending on valve size
• Union ends – 1/2” to 2”
• Flanged ends – 2-1/2” to 4”

Series 1140/1141 actuators:
• 8 temperature ranges for all valve body styles
• 40° F temperature range increments
• 10’ capillary length standard
• 100°F overprotection
• ± 10°F control accuracy
• Copper bulb
• 3 bulb diameter / lengths, depending on valve size

For more information on Hoffman Components Selector click here.

For more information on Series 1140/1141 click here.

Click here to download the August 2018 SteamTeam pdf file.

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HVAC system design requires methodical assessment of the options
Engineers must evaluate safety, costs, efficiency of VRF versus hydronics

click here to download the white paper

Rising energy costs and a movement toward sustainability are driving changes in the commercial HVAC market. As design engineers, building owners and mechanical contractors focus on increasing comfort and maintaining air quality while reducing overall energy consumption, the technology and components of HVAC systems are constantly being re-evaluated.

With heating and cooling among the largest costs for most buildings, building owners are intent on finding new and effective approaches for new buildings and improving performance of existing facilities. And as the industry continues the shift to sustainable building practices that maximize building performance while minimizing environmental impact, the type of HVAC system is an important factor in realizing energy- efficiency targets. Additional factors such as safety and code compliance, and costs related to serviceability and life cycle are among those that also must be considered in evaluating HVAC systems.

Two heating and cooling methods often compared in terms of energy consumption and system performance are hydronic systems and variable refrigerant flow (VRF) systems.

Hydronic systems as a room comfort technology have been in use in some form for centuries. Today’s hydronic systems provide water-based heating and cooling through pipes, ductwork and other components such as pumps, drives, controls, heat exchangers and valves.

VRF systems use refrigerant as the primary heating/ cooling medium, comprised of a main compressor unit connected through refrigerant lines to multiple indoor cassette units that can be individually controlled. They were developed in the 1980s in Europe and Asia and introduced in the United States about a decade ago.

While each has its place in commercial building HVAC systems, specifying engineers must be diligent in their review of project parameters and the applicable safety codes of ASHRAE Standards 15 and 34 to ensure they are making suitable selections. A closer examination of the key areas of differentiation between hydronic and VRF can also assist system designers in the process.

System capacity
When specifying a system, it’s important to consider not just building size, but also the size of the
HVAC system itself. Hydronic systems are better suited to handle buildings requiring 50 to 100 tons of cooling capacity or more. Hydronic systems also have the capacity to pump water efficiently over very long distances, such as a college campus or a high-rise office tower.

In contrast, system efficiency in VRF goes down based on the length of refrigerant pipe runs. ASHRAE Standards 15 and 34 define specific refrigerant concentration limits based on pounds of refrigerant per thousand cubic feet of interior volume beyond which acute toxicity is expected. Typically, refrigerant charge in a VRF system is 4 to 6 pounds of refrigerant per ton of cooling. To adhere to ASHRAE 15 requirements, the VRF system may need to be broken down into smaller refrigerant circuits, thus compromising the benefits of diverting loads.

VRF systems are generally limited to buildings fewer than 10 stories because the length of piping runs must be limited and zoned properly in order to carry refrigerants and oil through the building in accordance with manufacturer guidelines. Long lengths of piping can jeopardize performance of the unit ranging from oil or refrigerant accumulation in the piping to de-rated efficiencies.

Care must be taken to ensure the refrigerant piping is not installed down hallways or in a large open office floor plan, both of which are considered means of egress per standards set by ASHRAE and the International Association of Plumbing and Mechanical Officials (IAPMO). Even with ceiling-mounted fire suppression and sprinkler systems, these areas are still considered as the means of egress.

Refrigerants in question
While it’s possible for leaks to develop in both hydronic and VRF systems, a leak in a VRF system can be deadly. VRF refrigerant leaks can’t be detected by either sight or smell, making them hard to find and repair. In spaces with minimal ventilation, large concentrations of refrigerant gas in the air can put people at risk of asphyxiation.

Hydronic systems with cooling units also require refrigerant to operate, but the average system uses 66 to 75 percent less refrigerant than a VRF system of the same size, according to the Hydronics Industry Alliance. Hydronic systems are not exempt from the ASHRAE and IAPMO codes that govern the HVAC and plumbing industries, however, the refrigerant in a hydronics system is typically contained within a mechanical room, which, by code, is required to have the proper ventilation to deal with a potential leak.

Aside from the small amount of refrigerant associated with cooling units in a hydronic system, the water running through the system and in its pipes over the life of the system poses no safety or environmental risks.

The same cannot be said for VRF refrigerants. The Environmental Protection Agency issued major changes to the Section 608 rules of the Clean Air Act, which govern the handling, use and sale of refrigerants. Most notable is the regulation banning the use of hydrofluorocarbons such as R-410A in new chillers (air-cooled, water-cooled, scroll, screw and centrifugal), rooftop units and VRF systems beginning in 2024.

Under the updated rules, the EPA expanded the refrigerant management program, extending the regulations to non-ozone-depleting substitutes such as hydrofluorocarbons. This action lowers the allowable leak rate for comfort cooling and refrigeration appliances. It also incorporates industry best practices, such as verifying repairs and conducting annual leak inspections for systems that have lost a small amount of their refrigerant charge.

Service protocols
Proprietary VRF systems require specialized technicians for installation and maintenance — which can drive up costs — compared to hydronic water systems designed with universal components that can be installed and serviced by any HVAC service technician. Components in a hydronic system are factory made and tested, reducing rate of failure after installation.

Since VRF piping requires brazing and soldering on- site, the quality of the installation depends on the level of expertise of the installer. Installers also must be qualified to work with refrigerants under extremely high pressure and be knowledgeable about leak
detection and ventilation requirements per IAPMO and the International Code Council, which have adopted ASHRAE 15 Standards.

In addition, each VRF manufacturer has a different protocol, which further reduces the pool of qualified technicians for installation and maintenance. Improper installation and maintenance can cause premature failure of VRF systems.

With hydronic systems, component manufacturers can be changed and new technologies installed without impacting the other system components.

Cost differences
The initial cost of a hydronic system is generally lower, and systems offer a much wider range of flexibility for components, operation and maintenance, both in terms of parts and service. Advanced systems include application of technologies such as integrated and single-pipe systems that dramatically reduce piping and costs, and pumps equipped with variable speed drives that increase energy efficiency.

VRF systems generally have a shorter life expectancy than hydronic systems. Hydronic systems have been known to last 20 to 25 years, while VRF systems could need replacing as soon as 10 or 15 years after installation. The compressor in a VRF system is forced to work harder during heating cycles, reducing the life of the compressor.

At lower temperatures, hydronic systems are more reliable than VRF systems. That’s because a VRF system may require a supplementary heat source in cold climates, such as electric heat, which could negate the energy efficiency of the system. Without another heat source, the VRF compressor can be set to run at maximum capacity for the morning warm-up, but that takes more electricity, potentially negating any efficiency benefits, including reduced energy costs.

VRF system can provide simultaneous heating and cooling, and can recover heat from one zone and use it in another. This is effective in buildings with multiple temperature zones, such as a hotel. However, a VRF system does not have the capability of storing energy. Water in a hydronic system can draw the heat or chill out of a room and carry that energy back to the system for storage and later use, reducing energy consumption and costs.

Conclusion
These and other considerations have relevancy for building owners, architects, design engineers and all those who have a stake in commercial building HVAC system design, installation, operation and maintenance. Those who influence system selections must be diligent in their analysis to ensure systems are code compliant, energy efficient and adaptable to future energy sources. The most efficient systems in terms of cost, performance and efficiency will be in demand to help meet energy goals and keep building costs in line.

Kyle DelPiano is the Business Development Manager
– Commercial Buildings Services market for Xylem. He holds a bachelor of science degree in polymer and fiber engineering from Auburn University. He has nearly 10 years of experience in the HVAC industry in a variety of sales, training and marketing roles. In addition, he is an active HIA-C and ASHRAE chapter member and is LEED AP certified.

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Volume 5/ Issue 3/ December 2018

1. The system can’t vent fast enough.
If you can’t evacuate air from the system, steam can’t enter. It’s very important to vent the system quickly, to allow the steam travel to all radiators. Main vents are vital to the proper distribution of steam, so make sure to check them.

2. The boiler is piped incorrectly.
Modern steam boilers require the near boiler’s piping to help produce “dry” steam. Today’s boiler steam chambers are much smaller than the old ones, and steam riser connections are smaller than they used be.

3. The boiler is undersized.
A steam boiler’s job is to produce enough steam to fill the entire piping system and all the radiators. The job of the cold pipes and cold radiators is to condense this steam, but if the boiler can’t produce enough steam to overcome this mass of cold iron, the steam will not make it out to the furthest radiators. This is why you must size the boiler to the connected load, and then make sure the burner is fired to that load.

4. The steam traps have failed.
Two-pipe systems have radiator traps, and float and thermostatic traps. Their job is to pass air and condensate into the return piping, while preventing the steam from getting past the radiators and the ends of the mains. When these traps fail in the closed position, the air can’t get out, so the steam can’t get in. But when they fail in the open position, the steam passes into the return lines. Once there, it brings the returns to the same pressure as the supply lines and, with no difference in pressure, the steam stops moving. You have to make sure the steam traps are working properly for the system to operate efficiently.

No. 1A adjustable steam radiator vent and No. 40 steam radiator vent

5. The insulation has been removed from the pipes.
Steam mains are insulated so steam can reach all the radiators. When insulation is removed, the exposed steel piping becomes one very large radiator, and this additional load condenses the steam before it can reach all the radiators. If you see pipes that have their insulation removed, we suggest you either re-insulate them or make sure the new boiler is sized for this additional load.

6. The steam pipes are pitched incorrectly.
When installed correctly, steam mains and horizontal runouts are pitched to allow the condensate and steam to co-exist in the same pipe. Over the years, a building settles and pipe hangers loosen up, changing the pitch of the pipes and allowing condensate to pool along the piping. These puddles will condense the steam as it passes by, creating uneven heat throughout the building. Make sure the steam mains and runouts maintain their proper pitch.

7. The quality of the steam is bad.
If the boiler water is dirty or has a film of oil on its surface, the boiler will make “wet” steam. Because water droplets rob the steam of its latent heat, it condenses in the piping before it reaches all the radiators. Check the quality of the boiler’s water by looking at the gauge glass. When the boiler is making “dry” steam, the top portion of the glass will be dry. While the boiler is operating, raise the water line to within one inch of the top of the gauge glass. If water pours over the top, the boiler water is dirty and needs to be cleaned.

8. The wet return lines are partially plugged.
If the steam system has wet returns and is heating unevenly, make sure the returns aren’t plugged. If they are, the condensate will back up into the return, trying to overcome the additional pressure drop created by the plugged returns. Condensate will also back up into the main vents, closing them off before all the air is removed from the mains. This can create very uneven distribution of steam throughout the system.

9. Someone has set the pressuretrol too high.
Radiator steam vents have a rating that’s known as “drop-away” pressure. This rating has to do with the maximum system pressure at which the vent’s float can drop down to re-open when the steam condenses in the radiator. If someone raises the pressuretrol setting beyond the vent’s “drop-away” rating, it’s possible to close all the radiator vents in the system, and this leads to uneven distribution of heat throughout the building. Always check the pressuretrol setting on the boiler, as well as the “drop-away” rating of the vents in the system.

10. You haven’t contacted your local Bell & Gossett representative about your steam heating questions or problems.
Bell & Gossett’s people are well versed on all steam heating subjects, and they’re willing to share this information with you. All you have to do is give them a call.

Find your local representative:
http://bellgossett.com/sales-service/

Click here to download the December 2018 SteamTeam pdf file.

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Volume 5/ Issue 3/ December 2018

Is the brain more important, or the heart? Last time, we covered the controls of Domestic Pump units. Now it’s time to look at the heart of Domestic condensate handling equipment – their pumps and motor assemblies.

Domestic pumps are base components in the Domestic steam condensate handling equipment. They are also suitable for a variety of other applications, including hot water heating, irrigation, evaporative condensers, cooling towers, air conditioning units, milk coolers and booster service.

Generally there are two groups of pumps produced for all Domestic units, whether for condensate return, boiler feed or vacuum units: Centriflo C-types and B-types.

Centriflo® C-types are the most common pumps used in Domestic condensate handling equipment. Specially designed for the rigorous demands of this application, Centriflo pumps require a lower NPSH than conventional pumps. Vertical mounting saves floor space and gets the motor up above dirt and water. PF-style flange-mounted pumps can be simply bolted to flat vertical surfaces such as condensate receivers, eliminating suction piping completely. PVF vertical foot-mounted models come with footed NPT connect suction flanges and NPT discharge connections, for ease of use in other, piped applications. Here is an example of a C-type pump.

All pumps for the Domestic underground units are C-type, as well, but with longer shafts, as highlighted in green below.

Also, C-type pumps are exclusively used in Domestic vacuum units. They transfer the condensate, and play a major part in producing the vacuum, as well. The pump impeller lacks the close tolerances of other vacuum pumps. System debris of up to 1/8” can pass through the impeller with little to no detrimental impact, all the while continuing to assist in the production of the vacuum. The same can be said for the other vacuum producing components, which are not the topic of this article. However, please stay tuned for the next SteamTeam article to learn how the Domestic vacuum units work, and how that same water pump helps to produce and maintain the required negative pressure.

Now, let’s turn our attention to B-type pumps. The difference here is an additional suction inducer (propeller) and straightening vanes that create a positive pressure at the main centrifugal impeller, thus guaranteeing low NPSH pump requirements. Those pumps require only 2’ NPSH, and can pump condensate with a temperature of up to 210°F at sea level from a vented tank at the same level as the pump suction. Pumps mounted to a vented tank elevated 24” above the pump suction can pump 212°F water. Pumping from a closed loop system is limited to a maximum of 35 psi suction pressure, and may require alternate seals if temperatures exceed 250°F. The PF-B vertical pump can be flange mounted for connection directly to a tank. PVF-B is a vertical pump for separate, standalone floor mounting, and HB horizontal pumps are available for separate mounting. All pumps are bronze-fitted with bronze case wear rings, bronze suction inducers, bronze flow straightening vanes and stainless steel shafts.

Here are examples of vertical and horizontal B-type pumps, with the propellers highlighted in green and the straightening vanes highlighted in yellow.

Vertical B-type pump
Horizontal B-type pumpFeatures and benefits of all Domestic pumps
• Cast iron, bronze-fitted with stainless steel shaft
• Easily renewable bronze case wearing ring
• Heavy-duty ball bearing motor
• Stainless steel shaft
• Low NPSH, enclosed impeller
• Additional axial flow booster impeller for 2 ft. (0.6 m) NPSHR in B-type pumps
• Large impeller eyes and generously sized suction pipes and passages, to facilitate the pumping of hot water in condensate and boiler feed applications
• Vertical pump versions that protect the motor from moisture and dirt
• Suction flange for mounting directly on a tank or receiver
• Available feet for free-standing operation
• Standard carbon/ceramic mechanical seals designed for 250°F
• Optional Viton seals available
• 35 psi suction pressure
• pH = 7-9
• Available in 3500 RPM and 1750 RPM
• Impellers trimmed to nearest 1/16”
• C-pump capacities to 600 GPM, and pressures to 100 psi
• B-pump capacities to 160 GPM at 100 psi for vertical models, and to 340 GPM at 50 psi for horizontal models

Any questions? Let me know.
bozhidar.ivanov@xyleminc.com

Click here to download the December 2018 SteamTeam pdf file.

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Test content

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Goulds Water Technology launches AGS Series axial grinder pumps
Proven technology handles modern wastewater stream with ease

Auburn, New York — Dec. 18, 2018 — Goulds Water Technology, a Xylem brand, is introducing its new AGS Series axial grinder pumps that provide best-in-class performance against the challenges of solids, flushables and trash present in residential wastewater applications. With a semi-open impeller design, including an eight-hole cutter plate and three blade cutter, the AGS Series reduces problem waste to fine slurry, minimizing downtime and service challenges.

“Today’s residential wastewater stream poses more problems to plumbing systems than ever before with the proliferation of flushable wipes and other unconventional solids/trash items,” said Bo Gell, Americas Product Manager, Wastewater, Xylem. “The AGS axial grinders were developed with reliability and ease of service in mind. The pump technology tackles wastewater efficiently, which means a worry-free experience for homeowners.”

The Goulds Water Technology AGS Series outperforms other pumps on the market with its total dynamic head (TDH) and flow rates delivered across both .5 and 1hp models, enabling it to cover a wider range of applications. Additionally, the AGS Series is a true 2-inch discharge, making sewage pump replacement easy with no plumbing adjustments needed. A fixed balanced attachment simplifies installation, and is backed by a three-year warranty and industry-leading Goulds Water Technology service and support.

The AGS Series is available in single phase .5 hp (115V or 230V) and 1 hp (115V or 230V) options to fit a variety of residential sewage applications. It’s built to last with a stainless steel volute, eight-hole cutter plate and three blade cutter, a cast iron impeller, and a hardfaced silicon carbide on silicon carbide mechanical seal.

“We are actively advancing our wastewater product portfolio and technologies to stay abreast of the ever-changing residential wastewater environment,” Gell added. “By doing so, we’re not only able to combat contemporary wastewater issues; we can also better protect our aging infrastructure.”

More details on the AGS Series TDH and flow rates include:

• The .5hp model has a 42-foot TDH and a 46 gpm flow
• The 1hp product has a 66-foot TDH and 53 gpm flow

The Goulds Water Technology AGS Series is Built in the USA with proven grinder/cutter/impeller technology that has been used in other global Xylem brands for years. The new product line also points to the continual expansion of the Goulds Water Technology wastewater portfolio, designed to solve virtually any wastewater challenge.

Visit www.Goulds.com for more information about these high-performance axial grinder pumps and the entire Goulds Water Technology wastewater portfolio.

Follow Goulds Water Technology on social media:

• Facebook: @GouldsWaterTechnology
• Twitter: @GouldsWaterTech
• LinkedIn: Goulds Water Technology
• YouTube: @GouldsWaterTechnology

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About Xylem
Xylem (XYL) is a leading global water technology company committed to developing innova-tive technology solutions to the world’s water challenges. The Company’s products and ser-vices move, treat, analyze, monitor and return water to the environment in public utility, indus-trial, residential and commercial building services settings. Xylem also provides a leading portfolio of smart metering, network technologies and advanced infrastructure analytics solu-tions for water, electric and gas utilities. The Company’s more than 16,500 employees bring broad applications expertise with a strong focus on identifying comprehensive, sustainable solutions. Headquartered in Rye Brook, New York with 2017 revenue of $4.7 billion, Xylem does business in more than 150 countries through a number of market-leading product brands.
The name Xylem is derived from classical Greek and is the tissue that transports water in plants, highlighting the engineering efficiency of our water-centric business by linking it with the best water transportation of all — that which occurs in nature. For more information, please visit us at www.xylem.com.

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Brainpower for Rent: Xylem Rental Solutions makes its debut
Most extensive expertise, capabilities and portfolio in water technology industry

Rye Brook, N.Y. – Jan. 31, 2019 – In a move designed to bring the company’s global leadership in engineered water technologies to the growing rental market, Xylem is presenting a new approach and look to its dedicated rental solutions business. Xylem’s deep application knowledge and unrivaled family of pump and ancillary equipment brands deliver unparalleled value to virtually all industries and utilities. Xylem Rental Solutions boasts a fleet with the broadest range of sizes and configurations, also renting specialty products and systems that are not available from other companies.

“An ever-increasing number of industries are considering renting pumps and related equipment to efficiently and cost effectively run their operations,” said Gregg Leslie, Director Rental Market Development, Americas. “Whether our customers require fast-track temporary emergency response, or reliable, long-term operation, the depth of our expertise and breadth of our fleet will help them solve every water challenge, from the basic to the most complex.”

Xylem designs and manufactures all its own equipment, including proven brands such as Godwin, Flygt, Goulds Water Technology, AC Fire Pump and MJK. This technological authority enables the company to customize and optimize its rental solutions to help customers solve complex water problems across numerous industries and applications, including:

• Agriculture
• Commercial Buildings
• Construction
• Dewatering
• Environmental
• Industrial
• Marine
• Mining
• Municipal
• Oil & Gas
• Power Utilities
• Tunneling

Beyond specializing in the design and installation of rental solutions, Xylem provides holistic project management services and highly responsive customer support, ensuring minimal downtime, and greater efficiency, reliability and peace of mind.

“The days of using multiple suppliers for a single project are waning fast. Industry professionals want a partnership where they can get all their specific water challenges met from a single supplier, who also has the know-how and support services to back those system solutions up,” Leslie said. “It’s a Xylem capability that we’re excited to be offering and committed to expanding.”

For more information about Xylem Rental Solutions, visit www.xylem.com/RentalSolutions. To request a quote, find your nearest location on our website.

Follow us on social media:

• Facebook: @XylemRentalSolutions
• Twitter: @RentalXylem
• LinkedIn: https://www.linkedin.com/company/xylem-rental-solutions

###

About Xylem
Xylem (XYL) is a leading global water technology company committed to developing innovative technology solutions to the world’s water challenges. The Company’s products and services move, treat, analyze, monitor and return water to the environment in public utility, industrial, residential and commercial building services settings. Xylem also provides a leading portfolio of smart metering, network technologies and advanced infrastructure analytics solutions for water, electric and gas utilities. The Company’s more than 16,500 employees bring broad applications expertise with a strong focus on identifying comprehensive, sustainable solutions. Headquartered in Rye Brook, New York, with 2017 revenue of $4.7 billion, Xylem does business in more than 150 countries through a number of market-leading product brands.

The name Xylem is derived from classical Greek and is the tissue that transports water in plants, highlighting the engineering efficiency of our water-centric business by linking it with the best water transportation of all – that which occurs in nature. For more information, please visit us at www.xylem.com.

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Volume 6/ Issue 1/ April 2019

Yes it can. If you are interested to know more, please read on.

In addition to transferring condensate, one application for the Domestic Pump is to move air out of the way of the heating steam within a vacuum heating system. The advantages that come with vacuum systems are:

• Faster system heating
• Faster condensate return, to reduce system lag and prevent boiler cut-off on low level
• More even heating in remote sections of the system
• Lifting of low condensate returns without the use of an additional pump
• Energy savings, thanks to low-temperature boiling
• Installation savings, thanks to smaller pipes
• The ability to locate pipes in places you normally wouldn’t

The vacuum units in the Domestic Pump product portfolio include both condensate return and boiler feed units. But, no matter the unit type, the vacuum production part employs the same working principle. Domestic Pump products use condensate pumps to produce a so-called “liquid jet vacuum,” which works on the basis of Bernoulli’s Principle. This principle states that “pressure head + velocity head + elevation head = constant.” The three main components required for the job here are a centrifugal pump, a multi-jet nozzle and a venturi pipe.

Fig. 1 represents a vacuum-producing chamber. I will use it to illustrate the process.

The pump delivers a stream of water up through the piping, then horizontally through the nozzle, and then through the venturi pipe. The horizontal direction of the flow means that the change in elevation is negligible here – essentially a constant. Once the water passes through the nozzle, it’s broken into streams and injected into the venturi pipe, which narrows. But water is a non-compressible fluid, so the only way to get it through the narrowing is to accelerate the velocity. Following Bernoulli’s equation, if the elevation stays the same and velocity increases, then the pressure must go down in order for the equation to remain constant. The water, forced at high velocity across the gap between nozzle and venturi, entrains air and gasses through the air suction check valve, which is open at this time, thus lowering the pressure and creating smooth, steady vacuum in the system.

Then the mixture of water and air is discharged tangentially through the venturi into the separation chamber. This causes a whirling motion inside the chamber, where the water is forced towards the walls of the vessel, and the lighter air flows to the center and is discharged through the vent of the chamber. An additional benefit of that centrifugal motion is more available pressure at the pump inlet and less pressure resistance at the venturi pipe outlet. The pump will stop once the vacuum set point is reached, and then the air check valve will close in order to separate the system under vacuum from the vented chamber.

Finally, the equipment takes a well-deserved rest before starting the next cycle, triggered by a call for duty from the vacuum switch, which is adjusted in the factory based on the application. Most commonly, an average set point of 5.5” Hg vacuum is maintained at 160ºF condensate temperature. This is the ASHRAE recommendation for vacuum heating systems. However, using the described technology, the Domestic Pump MJ clinical and industrial vacuum units are capable of producing vacuums up to 28” of Hg. In this scale, 30” of Hg would be a perfect vacuum.

Cycle after cycle, the water in the vented separation chamber will slowly evaporate. That’s why the tank has a water level control. It consists of a level switch (either a float switch or a probe) and a solenoid valve. The switch will follow the water level and will signal the valve to open if the water level gets too low. The solenoid itself is installed on a make-up water supply line, and will let water into the chamber following the signal from the level switch.

So, by extracting water from the bottom of the chamber and pumping it though the impeller… out of the pump discharge… through the manifold elbow and a diverter… then into the nozzle… then across a gap to the throat of the venturi… we produce vacuum.

Any questions? Let me know.

Click here to download the April 2019 SteamTeam pdf file.

Check out our vacuum units: www.domesticpump.com

Bozhidar “Boz” Ivanov
Sr. Product Specialist
Domestic Pump
bozhidar.ivanov@xyleminc.com

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Volume 6/ Issue 1/ April 2019

With steam heating systems, you can count on one thing: They will always need feed water. How much water they need depends a lot on the system’s age and condition, but the feeding process never ends. Where does the water go? It leaves the system by evaporation, through leaky air vents on the radiators and mains. This type of leakage is especially aggravated by steam pressure that’s kept higher than necessary for the system, a condition we see all the time. And then there are buried pipes. Even if there are just a few feet of buried return line on the system, there’s a good chance it’s leaking.

Some home owners like to feed their steam boilers by hand, but the vast majority of home owners choose the convenience and back­up safety advantages of an automatic water feeder. That’s because their heating contractors took the time to explain the benefits to them. For instance, suppose there’s a leak in the system during the dead of winter when they aren’t home. An automatic feeder will keep the boiler running at its safe, minimum water line, and will keep the house warm. A feeder can also protect a steam boiler by keeping it fed with water should the gas valve lock itself in the open position.

How much water a boiler needs to keep operating depends on its firing rate, and this is very easy to calculate. It works like this: All boilers, regardless of their size, lose water to steam at a constant rate. Ideally, they should be fed at 1 GPM per 250,000 Btu/hr., Gross Load (D.O .E. Heating Capacity). So, if a boiler is rated for, say, 500,000 Btu/hr., and the water level drops to the feed line, you should be adding about 2 GPM to keep the burner on.

In residential steam heating, you can do this very effectively with McDonnell & Miller’s WFE Water Feeder. When boiler manufacturers reduced the size of new steam boilers, the people at M&M designed this feeder to protect those smaller boilers from nuisance shutdowns. The WFE Water Feeder takes its signal from either a Series PSE-800 probe-type or a Series 67 float-type low-water cutoff. It has a timing circuit that waits for a minute, feeds for a minute, waits for a minute, and so on. This well-thought-out feed cycle allows the condensate to return, greatly reducing the chance of a flooded boiler.

Series PSE-800 low water cut-off for steam boilers

It’s important to know that a new McDonnell & Miller WFE Water Feeder includes three separate orifices. There’s one already installed in the feeder at the factory, and it’s set to feed 2 GPM. This orifice will satisfy any steam heating boiler with a gross rating up to 500,000 Btu/hr. The feeder also comes with two additional orifices, one for a feed rate of 1 GPM, and the other for a feed rate of 4 GPM.

WFE Water Feeder

If you’re working with a very small replacement steam boiler – say, one rated at 125,000 Btu/hr. – you should use the 1 GPM orifice, which is good for boilers up to 250,000 Btu/hr. This smaller orifice will feed at a slower rate and lessen the chance that returning condensate will flood the boiler. If you have a larger steam boiler, one rated up to 1,000,000 Btu/hr, switch to the 4 GPM orifice. This larger orifice will let the feeder keep up with the needs of a bigger boiler and stop it from shutting down should a leak develop in the system.

Find your local Representative:
http://mcdonnellmiller.com/sales-service/
Browse the WFE Water Feeder web page:
http://mcdonnellmiller.com/water-feeders/wfe-uni-match-electronic-feeder/

Click here to download the April 2019 SteamTeam pdf file.

The post How much water should a steam heating system need? appeared first on Xylem Applied Water Systems - United States.

Volume 6/ Issue 2/ August 2019

There are both legal, and practical considerations that create the need to install mechanical or electronic low water cut-off (LWCO) control on a residential hot water boiler. From the legal side, jurisdictions have adopted codes which state when an LWCO must be installed, while the practical side is based upon system conditions.

ASME (American Society of Mechanical Engineers)
ASME Boiler and Pressure Vessel Code (BPVC) have been universally adopted as the minimum requirement for the manufacture, installation and maintenance of boilers. Section I, for Power Boilers, requires low water protection. Steam heating boilers of any size, regardless of where they are installed, must have a low water cut-off per ASME BPVC.IV. The same code only requires that hot water boilers with input greater than 400,000 btu must have a low water cut-off. In lieu of an LWCO, coil type boilers above 400,000 btu input, which require a flow of water to prevent overheating, shall have a safety device (typically a flow switch) to prevent burner operation when the flow of water is inadequate.

ASME CSD-1 (Control and Safety Devices)
CSD-1-2018 is an additional ASME standard for Controls and Safety Devices for Automatically Fired Boilers. As per Section 4, CSD-1 Part CW-120a requires at least one LWCO on all steam boilers, however the requirement for hot water boilers (Part CW-130a) have exception for residential boilers.

IMC (The Internal Mechanical Code)
This is a newer standard that is being adopted by jurisdictions. It is a consolidation of codes written in the past by BOCA, SBCC, and other independent code councils. Section 1007.1 of the IMC states “All steam
and hot water boilers shall be protected by a low water cut-off control.” If it’s a hot water boiler, it must have a low water cut-off.

2014 New York City Construction Code
SECTION MC 1007 BOILER LOW WATER CUT-OFF  1007.1 General.
All steam and hot water boilers shall be protected with dual low water cut-off control.
Exception:
Hot water boilers located within a dwelling unit supplying only that unit and having a total heat input of less than 350,000 Btu/h (1025 kW) may be protected by only one low water cut-off control.

The Reducing Valve
There has always been a controversy about whether to keep the fill valve open or closed after initially filling a hot water heating system. Bell & Gossett recommends closing the fill valve. If the valve is closed and there is a leak in the system, no water is added to the system which may cause damage to the boiler and flooding. Also a fill valve has a strainer, debris (sand, silt, minerals, rust, etc.) that is present in the water can clog the strainer. If the strainer is clogged, an open valve is no guarantee that water will flow, but if it does, a flood could result. The best practice in a hot water system is to fill the system, close the valve and install a low water cut-off to protect the system.

Piping Elevation
Some systems have piping for radiators, snow melt, and tankless water heaters below the minimum safe water level of the boiler. Boiler manufacturers and organizations such as the National Fuel Gas have recognized this. Each has added a section in their literature or standards that indicates that if a hot water boiler is installed above level of radiation, then a low water cut-off should be installed

For many years, industry leaders have identified the need for low water cut-offs on hot water boilers. They agreed that the only way to detect a low water condition is with a low water cut-off device. No other safety device can determine if water is present. In 1997, McDonnell & Miller introduced the Series RB line of probe type low water cut-offs. Designed for use in residential hot water boiler applications, they feature a green “power on” LED, a “low water condition” red LED, and high sensitivity for use in a water, and water-glycol mixture. The series RB are equipped with a self-cleaning probe for years and years of worry free protection. The Series RB can be installed in either the boiler tapping or supply riser and are easy to wire. They are an excellent choice as the device to sense a low water condition in a hot water boiler. Remember, even with the many other safety devices (temperature limits, pressure relief valves, flow sensors, etc.) installed on a hot water boiler, the low water cut-off is a low cost component which will protect the boiler and system from damage if a low water condition occurs.

Give your customer and yourself peace of mind, and install low water cut-off. It is a low cost way to protect property, health, and even life.

Since 1924 McDonnell & Miller company is protecting boilers in the USA and oversees from dry fire and offers many excellent mechanical and electronic low water cut-offs for hot water boilers.

Our featured electronic controls provide two different versions, based upon the power supply.

McDonnell & Miller RB-122E low water cut-off for residential hot water boilers is an excellent choice for oil or gas hot water boilers with 120V burner circuit.

RB-122-E Low Water Cut-Offs

• For residential and commercial applications
• Electronic operation
• Easy to install and wire
• Red LED indicating low water condition
• Green LED indicating power is on
• Test button
• Automatic reset
• No blow down required
• 20,000 ohms probe sensitivity
• Maximum ambient temperature 120°F (49°C)
• Maximum water temperature 250°F (121°C)
• Maximum water pressure 160 psi (11.2 kg/cm2)

For more information regarding Series RB-122E MM-238REVO.pdf

For more information regarding Series RB-24E please visit our website or download the pdf files MM-288C.pdf and MPF-009B RB 24E.pdf.

If you have additional questions regarding McDonnell & Miller products please see our website or contact our factory representative for your area mcdonnellmiller.com.

Click here to download the August 2019 SteamTeam pdf file.

The post Why residential hot water boilers need LWCO’s? appeared first on Xylem Applied Water Systems - United States.

Volume 6/ Issue 2/ August 2019

Float switches are very important part of Domestic Pump units. They perform variety of functions for both condensate return and boiler feed units. The switches are operated by the movement of the water level in the tank. They include electrical and mechanical parts. The electrical part is in a an electrical conduit box that is seen on the outside of the tank. The mechanical part includes a rod and a float – both of them are inserted into the tank and move up and down with the water level. When the float reaches the required set point it will either close or open the electrical contacts, depending upon the position of the float switch and the type of control.

Condensate return units include pumps that are controlled by the water level in the tank. When the float of the float switch reaches the preset high point, it will close the electrical contacts on the switch and power the pump. The pump will then start pumping the water out of the tank until the float drops to its low point and opens the contacts on the switch thus stopping the pump. The float controls ensure there is some water left in the tank to keep the pump primed and the float switch starts the pump before the tank overflows. Each pump may have its own dedicated float switch (photo 1), or the unit may be equipped with a duplex switch called “mechanical alternator” (photo 2). The mechanical alternator will control two pumps with a single float in the tank. This alternating device will sequence the lead-lag role of each pump thus operating the two pumps more evenly, and its single float provides space for installing more control switches in the tank.

Photo 1: A float switch and a simplex unit with the float switch on.

Photo 2: A mechanical alternator and a duplex unit with the mechanical alternator on.

There is a variation of the mechanical alternator that very much looks like it but its alternating function is disabled. Why? Because some customers prefer to have an electrical alternator instead, or to not have alternation at all, but include an additional float switch, say for a high level alarm. This, combined with fewer openings on a smaller tank is the reason to use the non-alternating duplex switch. Here is an example – you need to control two pumps without mechanical alternation, and you also need to have high level alarm switch, too, but the receiver tank can only accommodate two float switches. The solution to that example is to use the duplex non-alternating switch and a second switch for the high level alarm. The working principle of the high level alarm float switch is the same but its function is to send a signal to the control panel and trigger an alarm.

Speaking of alarms – what about the low water level alarm? Here, opposite to the high level switch, we would need the contacts to close when water level drops too much. We can achieve this by using a float switch with reverse action. Such a switch is also used to control a make-up water solenoid that is normally closed. The two examples for reverse-action float switch are primarily used on boiler feed units. Those units are not controlled by the water level in their own tank, but by the water level in the boiler they are feeding. That is why we use safety switches like for low level alarms, for controlling make up water connections, and for stopping the pumps in case the water gets so low that even the make-up water capacity cannot catch up with the boiler demand.

Float switches are robust, long-lasting and a simple solution for opening and closing electrical circuits. Once the user has selected the required unit features and enclosures, they do not need to worry about switch design, dimensions, materials or adjustment. Just get yourself familiar with the operating manual and remove the shipping bracket off the switches before operating the unit – all else has been covered and tested in
the factory.

Any questions? Let me know.

bozhidar.ivanov@xyleminc.com

Check out our products on www.domesticpump.com

Click here to download the August 2019 SteamTeam pdf file.

The post Switch to Domestic Pump appeared first on Xylem Applied Water Systems - United States.

Helping engineers sort out PEI in pump selection and efficient system design
DOE energy rating includes constant load and variable load equipment

Beginning Jan. 27, 2020, clean water pumps sold in the United States must achieve a minimum energy rating of 1.0 as outlined in the Energy Conservation Standards for Pumps established by the U.S. Department of Energy (DOE) and adopted by Natural Resources Canada. Even though that number denotes compliance with the new standards, a compliant pump by itself is not a measure of an efficient hydronic HVAC system.

Specifying engineers intent on designing mechanical systems for commercial buildings that lower energy consumption, reduce maintenance and extend the life of system components must take a deeper dive into the DOE’s metric to ensure they are selecting the most efficient pumps for the application.

Understanding the components of the DOE’s Pump Energy Index (PEI) is a good place to start. In establishing the PEI to rate the performance of pumps, the DOE offered pump manufacturers methods to determine PEI for either constant load or variable load equipment classes. PEICL applies to pumps sold without variable speed controls; PEIVL applies to pumps sold with variable speed controls. While the goal of the DOE’s initiative was to improve the overall efficiency of pumps sold in the United States, it also wanted to encourage the use of variable speed controls in variable load systems to maximize energy savings — thus the reason why it utilizes two PEIs for a pump.

With an HVAC system accounting for up to 50 percent of a commercial building’s energy use, designing efficient heating and cooling systems is critical to keeping a project on budget as well as meeting sustainability goals. Variable speed drives often are applied to existing systems to increase overall efficiencies. When a VSD is installed properly, pumps can work more efficiently, thereby extending product life, reducing energy consumption and decreasing electrical system stress.

With HVAC systems accounting for as much as 50 percent of a commercial building’s energy use, efficiency is a priority in system design. A new Department of Energy pump efficiency standard is changing the way engineers select pumps for hydronic systems.

The pump industry has been working toward the 2020 compliance deadline for the last few years, with individual manufacturers weighing their options in terms of hydraulic redesign of pump lines, discontinuing certain models or achieving compliance on a noncompliant pump by combining it with a variable speed drive. The standard requires the efficiency rating of a basic model be based on the least efficient or most energy-consuming individual model. The DOE estimates that the least efficient 25 percent of pumps on the market today will be eliminated through this process by 2020.

Energy Rating tool
In order to compare the efficiency of pumps in accordance with the DOE standards, the Hydraulic Institute (HI), in conjunction with industry partners such as Xylem Bell & Gossett, have created an Energy Rating (ER) metric based on the DOE’s PEI. To use the ER label, pumps must perform to published performance data, be tested to DOE test standards in a Hydraulic Institute certified test lab.

The HI Energy Rating is similar to the ENERGY STAR program for household appliances. It provides estimated annual power savings for a specific pump along with the DOE-required PEI information. Products with the ER label are listed in a database on the HI Energy Rating Portal, http://er.pumps.org/ratings/search, searchable by manufacturer, model number and rating ID listed on the hydraulic energy rating label distributed with the pump.

Which PEI?
How should specifying engineers use PEI to maximize efficiency in a hydronic system and make informed decisions about using compliant pumps? The answer, in part, depends on the application.

In applications in which the load is constant — such as cooling needs in a data center — engineers could consider only PEICL. Making an apples-to-apples comparison of different pumps in the PEICL category will demonstrate differences in efficiency based on the PEI for each pump. The example below demonstrates how even a small change in PEI can have a sizable impact in efficiency.

Let’s compare two 5-horsepower end suction pumps. Pump A has a PEICL of 0.89, which is comfortably under the 1.0 standard. Pump B has a PEICL of 0.95 — still within standard, but not quite as efficient.

The bottom of the energy rating label provides information on how to estimate savings versus the baseline (PEI 1.0) end suction frame mounted pump. If Pump A’s motor is 90 percent efficient and operates close to 5 hp, input power will be 5.55 hp, or 4.1 kW.

Taking 4.1 kW, multiplying by 11 and dividing by 100, gives you the savings factor of 0.45. Multiplying that by operating hours and cost per kW, one can determine cost savings between this pump and the baseline pump. For example, 6,240 hours at 10 cents per kW would mean an annual savings of $280 in operating costs (0.45 x 6,240 x 0.10) for Pump A. It doesn’t take much to realize that 11 percent annual savings on a 25-hp or 50-hp pump adds up quickly!

Pump B with a PEI of 0.95 would have an ER of 5. Following the same calculations, this less efficient pump will yield less than half the savings annually than Pump A.

When demand fluctuates

In commercial building hydronic HVAC systems, the load varies depending the heating and cooling needs of the occupants. In variable load environments, applying a variable speed drive to slow down or speed up the pump to match system demand is the key to reducing energy consumption. Using the PEIVL metric, engineers can accurately compare products to ensure the most efficient hydronic system design.

When comparing the same pumps from the first example on a PEIVL level, Pump A has a PEIVL of 0.46, well below the 1.0 baseline requirement. With an ER of 54, one could expect a sizable energy savings.

Pump B has a PEIVL of 0.51 and an ER of 49. Even though there are similar relative values between the constant load and variable load ratings, a pump with a PEICL of 1.01 — which is a failing number — could have a PEIVL at or below that pump’s 0.51.

That can make things a little confusing when doing pump comparisons. In order to ensure hydronic HVAC systems are being designed from the start with the most efficient pumps, engineers should look at both PEICL and PEIVL with key emphasis on PEICL to confirm that the pump they are specifying has a rating of 1.0 or less. If a pump requires a drive to meet efficiency standards, then it’s not going to be as efficient as another pump-drive combination that has a better bare pump rating.

Be aware that PEICL data may not be made available for every pump, meaning that it may not have been tested or may not be compliant. If the numbers are dramatically different and the pumps are similar, then you can be more comfortable with these comparisons. It’s also important to remember that the efficiency of those pumps in a system will be impacted by the load profile and how close the pump operates to best efficiency point.

Notice in the two examples that the PEIVL numbers are much lower than PEICL numbers. The PEIVL number is a power comparison against the baseline pump, which is the same constant speed calculation used in the PEICL number. This means that the PEIVL numbers will always be much lower than a PEICL number, considering the reduced flow and head points used in the calculation for variable speed. This makes sense, as in any situation with a variable load you will gain efficiency by utilizing variable speed. To optimize efficiency, you still want to marry that motor and drive with the most efficient pump.

In the second example, Pump A has a lower PEIVL than pump B, but that does not necessarily mean it will cost less to operate in a system. Different types of pumps have different baselines; engineers should be sure they aren’t making an apples-to-oranges comparison. Using a related example to illustrate the point, if the energy rating on a refrigerator is lower than the energy rating on a furnace, that doesn’t necessarily mean that the furnace will be cheaper to operate.

Beginning in January 2020, clean water pumps sold in the United States
must meet efficiency standards and include efficiency information on the pump nameplate.

Making use of available tools
The HI Energy Rating program has become an impetus for public utilities to put in place pump energy rebates as a way to encourage energy conservation. Pacific Gas & Electric (PG&E) public utility in northern California began offering rebates for pumps that exceed the DOE’s PEI metric, requiring pumps to meet a .96 value in February 2018.

The more stringent energy efficiency requirements of utilities such as PG&E — and likely the first of many to do so — underscore the need for specifying engineers to incorporate energy rating tools in pump selection and system design.

Bell & Gossett has been a leader in developing tools for the industry to support efficient pump selection, such as through its ESP-SystemwizeTM online selection tool that provides HVAC system designers the ability to choose all system components within a single integrated tool to ensure the most efficient hydronic system design.

Even though the PEIVL number considers loads at 100 percent, 75 percent, 50 percent, and 25 percent of flow, it won’t be an accurate comparison for all part load efficiency profiles. That’s because the curve used for calculating PEIVL has a specific formula for determining head at each of the reduced flow points, which won’t necessarily match the system curve for a specific design. Also, each of the flow points in the PEIVL number is rated equally. The Bell & Gossett guidance for weighting efficiency is 100 percent flow (duty point), only 1 percent of the year; 75 percent flow, 42 percent; 50 percent flow, 45 percent; and 25 percent flow, 12 percent.

When comparing pump efficiencies, it is always good to use selection software that has built-in cost estimation based on the load profile. That information, plus pump PEI data and ER data, is available on ESP-Systemwize.

We’re already seeing a snowball effect in regard to pump efficiency requirements — utility rebates are just one example — and more are to be expected as the industry continues its shift toward energy efficiency. The 2019 version of ASHRAE Standard 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings, is currently being updated to include verbiage requiring the use of DOE compliant pumps. Engineers play an important role in efficiency efforts; it’s critical they continue to acquire the necessary knowledge to design mechanical systems that set the standard for years to come.

Mark Handzel is Global Vice President, Product Regulatory & Government Affairs, Xylem Inc. He has 36 years of experience with pumps and related equipment and served as a member of the U.S. Department of Energy Appliance Standards and Rulemaking Federal Advisory Committee’s Commercial and Industrial Pumps Working Group and also on the Circulator Pumps Working Group.

Alan Jones is the global product manager for Bell & Gossett centrifugal pumps. He holds a bachelor of science degree in systems engineering from the United States Military Academy at West Point, and a master’s in business administration from Syracuse University. He is an ASHRAE chapter member focused on customer experience, energy efficiency, system integration and value generation.

Click here to download the pdf file

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About Xylem
Xylem (XYL) is a leading global water technology company committed to developing innovative technology solutions to the world’s water challenges. The Company’s products and services move, treat, analyze, monitor and return water to the environment in public utility, industrial, residential and commercial building services, and agricultural settings. With its October 2016 acquisition of Sensus, Xylem added smart metering, network technologies and advanced data analytics for water, gas and electric utilities to its portfolio of solutions. The combined Company’s nearly 16,000 employees bring broad applications expertise with a strong focus on identifying comprehensive, sustainable solutions. Headquartered in Rye Brook, New York, with 2015 revenue of $3.7 billion, Xylem does business in more than 150 countries through a number of market-leading product brands. The name Xylem is derived from classical Greek and is the tissue that transports water in plants, highlighting the engineering efficiency of our water-centric business by linking it with the best water transportation of all – that which occurs in nature. For more information, please visit us at www.xylem.com.

The post Helping engineers sort out PEI in pump selection and efficient system design appeared first on Xylem Applied Water Systems - United States.

Leveraging the power of parallel pumping
Best efficiency staging achieved with technologically advanced controllers and variable speed drives

Vince Lombardi’s Green Bay Packers were famous for their power sweep, and ran the play over and over again with great success. When opposing teams began making adjustments to stop the sweep, Packers quarterback Bart Starr read the defense at the line of scrimmage and could alter the play to ensure the best outcome.

In a parallel pumping system, the controller is the quarterback that dynamically makes decisions based on what the defense — or current flow and head requirements — shows. Variable speed control in a parallel pumping system is a proven method of increasing efficiency and reducing costs, but even greater efficiencies and savings are attainable when designers combine advanced logic controllers and today’s more economical variable speed drives.

Think of it as employing a bit of West Coast Offense to the pump staging process to create a powerful solution that comes with high efficiency, backup capacity and potential savings on space and initial investment.

In an environment where partial loading is the norm, optimizing system performance isn’t as simple as optimizing pump performance at a single duty point. The entire profile of the pump’s efficiency at varying flows and speeds must be considered. In a parallel pumping environment, this makes both selection and staging strategies that much more complex. That’s where technology comes into play to help get to these solutions more easily, and parallel pump controllers with best efficiency staging capability pay dividends.

To meet the demand for energy-efficient pumping systems in today’s
commercial buildings, the Bell & Gossett PPS Parallel Pump System offers
advanced features that provide users the ability to better control pump operation
and provide critical information on pump efficiency and pump performance.

Selecting a pump for parallel operation using the same methods as choosing a single pump involves simply cutting the flow in half or a third and picking the most efficient option. When flow gets past 120 percent of Best Efficiency Point (BEP), it’s time to stage the next pump. However, that process doesn’t leverage technology, and though the system will provide required head and flow, it likely won’t be at optimal efficiency.

How can one be sure that pump staging is really optimized for efficiency? By examining different staging scenarios and comparing and contrasting the weighted part load efficiency values (PLEV), the challenges and solutions of designing parallel pumping systems become clear.

In the first scenario, the full load requirement is 4000 GPM at 65 feet of head with a control head requirement of 19.5 feet. These design parameters should be carefully considered, as they dictate the system curve that will be driving the selection decisions — grossly overestimating head values will lead to challenges in commissioning.

With that large of a pump, the selection would likely be a double suction pump. In Figure 1, the curve depicts an efficient solution, especially at full load. There is some tapering at 50 percent and 25 percent of load, yielding a weighted part load efficiency value (PLEV) of 81.6 percent. This is a 10x12x15.5 pump with a 100 hp 6-pole motor, a large investment and footprint, but one that provides zero backup capacity.

Figure 1
10x12x15.5 double suction pump with 100 hp 6-pole motor

Now let’s examine an option for parallel pumping that provides backup capacity and even greater PLEV. Figure 2 shows two end suction pumps in parallel — 8x10x13.5-inch pumps with 50 hp motors. This constant speed graph demonstrates efficiencies over 86 percent for portions of this curve, which means that there will only be improvements over the curves when variable speed is introduced into the equation. In general, the system curve crosses all of the test speed curves and demonstrates acceptable efficiencies.

Figure 2
2 parallel 8x10x13.5 end suction pumps with 50 hp 6 pole motor

Figure 3 reflects individual pump efficiency improvements created by variable speed. Dividing the flow between both pumps at full load, efficiency is 86.3 percent — even higher than the double suction pump in Figure 1. If both pumps continue to run at partial loads, the weighted efficiency comes in at 77 percent, below the double suction performance. As demand decreases, the second pump must be destaged. As system requirements drop below 2400 GPM, the two-pump efficiency is actually dropping below 80 percent, while the single-pump efficiency is increasing from 80 percent and climbs to 88 percent as demand drops to 1400 GPM. In the case of this particular pump based on this system curve, it appears that the best staging/destaging occurs around 10 percent past BEP. With two parallel pumps one pump can drop off and the system will still operate at 75 percent capacity.

Figure 3
Single 8x10x13.5 end suction pump variable speed curve running as
one of two pumps and solo at 100%, 75%, 50% and 25% of load

Figure 4 outlines a three-pump option with a 6x8x9.5 end suction pump. With this combination similar efficiency is achieved with 4 pole motors. Note that versus the total 100 hp in the previous examples, it’s now at 90 total hp (three, 30 hp motors).

Figure 4
3 parallel 6x8x9.5 end suction pumps with 30 hp 4 pole motors

Figure 5 demonstrates coverage up to 50 percent of load with one pump — if system losses have not been underestimated. (This would need to be tested in use and the system throttled if necessary). With two pumps, nearly 90 percent of load is covered. In fact, if the requirement was to meet full duty with two pumps, motors and drives could be upsized to 40 hp and the pumps over-sped to almost the same efficiency as the pumps in Figure 5 that is just short of 60 feet at 2000 GPM per pump. Based on the efficiency profile of this pump, optimal system efficiency will be achieved by running two pumps from 3600 GPM all the way down to just over 100 GPM or the 25 percent partial load point.

Figure 5
6x8x9.5 end suction pump variable speed curve running in parallel
as one of three pumps, one of two pumps, and solo at 100%, 75%, 50%
and 25% load

The initial investment savings on three 30 hp 4-pole motors versus a 100 hp 6-pole motor is 40 percent. The initial investment savings on a three 6-inch pumps versus the single 10-inch pump is roughly 25 percent. (There will be some offset to the savings for the additional parallel piping.)

Figure 6 shows the efficiency benefits that can be achieved by determining the optimal staging point for each parallel pumping solution. It is important to evaluate the system curve and pump efficiency curves to optimize staging. In these scenarios, optimal staging in a parallel pumping solution can save 3 percent on energy costs versus the double suction solution while increasing backup capacity and potentially eliminating system downtime required for maintenance. However, if staging is not done properly, the system might actually operate 3 percent less efficiently than the single-pump solution, which could mean over $1,000 in increased energy costs per year depending on operating conditions and utility rates.

Figure 6
Table of part loads considering 100% flow at 1%, 75% flow at 42%;
50% flow at 45%; and 25% flow at 12%, considering no staging
and optimal staging

The staging points are based on the system design and anticipated system losses. In these examples, we are modeling the system utilizing a system curve, but we know the system will operate in this area. In actual application, this will need to be reviewed following commission. It should also be understood that in a diverse system, there is a control area rather than a simple control curve. The more diversity in the system, the larger this area and the greater the benefit from dynamic, real-time staging performed by a capable pump controller versus a fixed staging strategy based on predetermined staging points.

According to the 2016 ASHRAE Handbook for HVAC Systems and Equipment, Section 44.3.5: “The area in which the system operates depends on the diverse loading or unloading imposed by the terminal units. This area represents the pumping energy that can be conserved with one-speed, two-speed or variable-speed pumps after a review of the pump power, efficiency and affinity relationships.”

Staging solutions for best efficiency can be complex, but with the aid of a capable quarterback — a parallel pump controller equipped with built-in best efficiency staging — all of these calculations happen dynamically, ensuring that the system can actually deliver these theoretical efficiencies.

Alan Jones is the global product manager for Bell & Gossett centrifugal pumps. He holds a bachelor of science degree in systems engineering from the United States Military Academy at West Point, and a master’s in business administration from Syracuse University. He is an ASHRAE chapter member focused on customer experience, energy efficiency, system integration and value generation.

Click here to download the pdf

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About Xylem
Xylem (XYL) is a leading global water technology company committed to developing innovative technology solutions to the world’s water challenges. The Company’s products and services move, treat, analyze, monitor and return water to the environment in public utility, industrial, residential and commercial building services, and agricultural settings. With its October 2016 acquisition of Sensus, Xylem added smart metering, network technologies and advanced data analytics for water, gas and electric utilities to its portfolio of solutions. The combined Company’s nearly 16,000 employees bring broad applications expertise with a strong focus on identifying comprehensive, sustainable solutions. Headquartered in Rye Brook, New York, with 2015 revenue of $3.7 billion, Xylem does business in more than 150 countries through a number of market-leading product brands. The name Xylem is derived from classical Greek and is the tissue that transports water in plants, highlighting the engineering efficiency of our water-centric business by linking it with the best water transportation of all – that which occurs in nature. For more information, please visit us at www.xylem.com.

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Xylem study analyzes life-cycle cost of HVAC systems
Hydronic systems outperform VRF, analysis finds

Introduction
Upfront costs and energy consumption are primary drivers when selecting a commercial HVAC system in new and retrofit projects. A new study commissioned by Xylem underscores the importance of evaluating total life-cycle cost in the selection process to adequately identify pros and cons of the various system types.

To anecdotally compare and contrast HVAC systems according to their 30-year life cycle cost analysis (LCCA), the Xylem study analyzed seven elementary and middle schools located in South Carolina Climate Zone 3A, a humid, warm climate. The cost analysis includes upfront installed cost, replacement cost allocations and ongoing energy and maintenance cost of the following system types:

• Variable refrigerant flow heat pumps (VRF)
• Water source heat pumps (WSHP)
• Ground source heat pumps (GSHP)
• Direct expansion rooftop units (DX RTU)
• Water cooled chillers (WCC)
• Air-Cooled Chillers (ACC)

With HVAC systems dictating as much as 50 percent of the overall energy use of K-12 buildings, according to ENERGYSTAR, the results of the Xylem study serve to inform decisions and promote maximized energy savings across the commercial construction industry.

Methodology
Over a three-year period, utility cost (electric and natural gas) and average maintenance cost were collected. For a more accurate comparison, construction costs were estimated according to the year each building was built, and utility rates and square footages of these facilities were also normalized to remove any other outside factors. The average electric rate ($k/kWh) and natural gas rate ($/therm) from the sample buildings were multiplied by each building’s electric and natural gas consumption to calculate a normalized energy cost ($/SF) for each building. Each building’s square footage was also considered when calculating maintenance and installation cost.

Findings
From a life-cycle cost perspective, the primary drivers of a purely economic decision of all HVAC system types are installation and energy cost. However, these costs are often interrelated with a maintenance department’s unfamiliarity and uncertainty with any given system, eventually showing in the form of increase utility cost from overrides and other changes to the system design.

The study’s findings resulted in the following ranking in life-cycle cost analysis from lowest to highest.

As exhibited in Figure 1, replacement allocations had an impact on the life-cycle cost analysis (see yellow bars) and drastically reduced the cost effectiveness of equipment with 15-year life expectancies.

Figure 1

Conclusion
As design engineers, building owners and mechanical contractors strive for more sustainable and energy-efficient practices, these findings shed light on the differences among systems, particularly hydronic and VRF systems. Considerable benefits of hydronic HVAC systems include lower energy usage intensity and cost, wider range of maintenance flexibility and longer life expectancy.

Specifically, the schools with WSHP and GSHP systems displayed energy use levels that were 30 percent (40.7 kBtu/sf) and 41 percent (34.4 kBtu/sf) better than the national median for elementary and middle schools (58.2 kBtu/sf), respectively. The replacement cost allocation also acknowledged that the tested hydronic systems operate effectively for approximately 25 years. The tested VRF systems require replacement a decade earlier because of their tendency to work harder during heating cycles, ultimately bringing proof of long-term cost savings to the forefront of the conversation surrounding sustainability and hydronic HVAC system efficiency.

Click here to download the pdf

Follow Bell & Gossett on social media:

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About Xylem
Xylem (XYL) is a leading global water technology company committed to developing innovative technology solutions to the world’s water challenges. The Company’s products and services move, treat, analyze, monitor and return water to the environment in public utility, industrial, residential and commercial building services, and agricultural settings. With its October 2016 acquisition of Sensus, Xylem added smart metering, network technologies and advanced data analytics for water, gas and electric utilities to its portfolio of solutions. The combined Company’s nearly 16,000 employees bring broad applications expertise with a strong focus on identifying comprehensive, sustainable solutions. Headquartered in Rye Brook, New York, with 2015 revenue of $3.7 billion, Xylem does business in more than 150 countries through a number of market-leading product brands. The name Xylem is derived from classical Greek and is the tissue that transports water in plants, highlighting the engineering efficiency of our water-centric business by linking it with the best water transportation of all – that which occurs in nature. For more information, please visit us at www.xylem.com.

The post Xylem study analyzes life-cycle cost of HVAC systems appeared first on Xylem Applied Water Systems - United States.

Volume 6/ Issue 3/ October 2019

The well-known Domestic Pumps from Xylem can handle up to 212ºF of boiling condensate, without cavitating, without vapor locking and in many cases even without elevating the tank. Units will do their job and transfer the condensate back to the boiler room, or to the boiler itself. The condensate will travel through pipes, fittings, ups and downs, before reaching its final destination. If it is a boiler feed pump then overcoming the operating pressure of the boiler should be accounted for, too. All the pipes and fittings along the way will try to give our pump a hard time because of the pressure drop along them.

To calculate this pressure drop you have to take into account how far you’re going, and how high you’re going. Sounds simple but it may not be. How far includes not only the distance but also the equivalent distance for each fitting, each valve, each elbow, and the losses for all the piping. How high refers to elevation, but elevation can be both positive and negative. This means careful review of plans, or specifications that have already taken all of this into account and determined what the total losses to the pump are in the discharge piping before the pump delivers its condensate to where it needs to be.

For low pressure boilers less than or equal to 50 psi the discharge pump pressure needs to be greater than the losses by a minimum of 5 psi. If losses are 10, we take 15. For systems where boiler pressures are greater than 50 psi, your discharge pump pressure needs to be greater than the losses by a minimum of 10 psi, in order to be on the safe side. If we run the unit under vacuum then another 5 psi should be added on top of the above rule, since the pump will be pumping out of an average of negative 5 psi. Sizing the pump is vital for proper operation.

Domestic Pump has standard solutions to overcome up to 100 psi of back pressure and this is more than enough for most steam heating applications.

But what happens when the pressure drop along the discharge piping is higher than 100 psi? Such applications can be found in industrial facilities or in larger steam heating systems with longer and more complex return piping. The solution to that is coming from our large Xylem family, and it is the Gould’s e-SV stainless steel multi-stage pumps. Utilizing the e-SV multi-stage delivers a great solution for high pressure condensate and boiler feed units with an efficient and easy-to-maintain multi-stage pump.

B&G Domestic Elevated Boiler Feed Units CMED

Here are just a few benefits from the synergy between Domestic Pump and e-SV:
• Pumps up to 500 psi discharge pressure
• Stainless steel multistage pumps
• Flexible pump solutions

Most importantly we make sure that the selected e-SV pump models will also transfer boiling water without cavitating and without the need to oversize them. This is achieved by selecting those models that meet the same required net positive suction head (NPSH) like the ones of the Domestic Pumps. All of our units are vented to the atmosphere. This means that the max. temperature of the condensate is 212ºF and it is a matter of atmospheric pressure and available water column at pump inlet to provide the required NPSH at pump inlet. We have taken care of that and the design of the units, including tank elevation and types of pumps, will meet the application requirements. Like with Domestic Pump, the e-SV models also have a low-NPSH version to transfer condensate with temperatures at the higher end.

Custom condensate return unit, model CED-e-SV

In addition to the standard pump options, like discharge pressure gauge, 60 or 50Hz applications, and motor enclosures, we can also add different pump discharge connection styles and different materials for the volute and seals.

Currently there is a number of standardized CMED-e-SV boiler feed models available. Customized units are always available for both Condensate Return and Boiler Feed Units utilizing a range of cylindrical and/or elevated receivers.

Please feel free to reach out with your custom unit inquiry and questions.

Check out our products on www.domesticpump.com

Bozhidar ‘Boz’ Ivanov
Sr. Product Specialist, Domestic Pump
bozhidar.ivanov@xyleminc.com

Click here to download the October 2019 SteamTeam pdf file

The post How to manage a broader range of pressure? appeared first on Xylem Applied Water Systems - United States.

Volume 6/ Issue 3/ October 2019

When a steam trap fails to open, and allows live steam to pass by, it is easy, and convenient to ignore symptoms or place on our never-ending list of “things to do.” After all, what harm is it besides wasting little energy that cost a few bucks? The boiler is still running, building is heated, tenants are not complaining, and everything seems to be fine. However, a failed trap will cost you more than just the loss of a small amount of steam. It will cost you a lot more.

The Cost of Lost Steam
Let’s examine how a trap passing steam can affect the whole steam system. First, you need to determine how much the loss of steam really costs. Since the steam is being lost at saturation condition (0 psig from the vented tank receiver) we can determine amount of energy (Btus) that will not be recovered. 0 psig steam contains 970 Btu/lb. So, for every pound of steam we don’t recover, we lose 970 Btu’s. But we’re losing more than just that latent energy. This is only a part of energy wasting. We are also losing sensible energy. Having lost that pound of steam, we must now replace it with a pound of water and we have to add energy to the new water just to bring it up to saturation condition (for water it is approximately 1Btu/lb°F). Let’s say the water we are introducing is 60°F. Because we lost our steam through a vented receiver, we have to raise its temperature to 212°F. And because the steam we lost had already been treated, there is the additional cost of treating the new water. Now let’s see how much it can cost you.

Single trap with 3/8” orifice discharging 100 psig of steam to atmosphere will cause a steam loss of 652 lb./hr. Since each lb. of steam is equivalent to about 1,000 BTU/hr. Loss will be 652,000 BTU/hr.

On gas fired boiler, operating at 70% efficiency will produce about 70,000 BTU for each Therm of Natural Gas. The gas required to replace the lost of steam will then become 652,000 BTU/hr. ÷ 70,000 BTU/Therm. or 9.31 Therms per hour.

If Natural Gas cost $1.27/therm. (US average June 2018 bls.gov) the money wasted due to the faulty trap becomes $11.82/hr. (9.31 * 1.27). If the boiler is operating 241 days/year. October 1st – May 1st 10 hours/day it becomes $28,486/year.

The significance of these savings becomes rapidly higher when you consider that an even small steam system usually has several traps, and larger system can have more than 1,000 traps.

Other Effects of failed Traps
Having this information we are able to calculate the energy loss associated with losing steam through a bad trap. However, there are other indirect costs related to the failed trap that are more difficult to calculate. One is the damage caused by water hammer. As steam enters a condensate return line, there is the chance steam will mix with the condensate and some of the condensate may flash into steam and collapse into condensate, causing water hammer…remember this banging pipes? Water hammer can cause serious damage to steam system. One failed open steam trap may destroy the rest of the traps, (Remember when you are replacing a thermostatic element it is extremely important to replace all before restarting the system).

McDonnell & Miller float destroyed by water hammer

A failed trap can pressurize the return main resulting in insufficient differential pressure across other traps draining into the same main as the failed trap. Consequently, condensate will back up in the processes the traps are associated with. Someone will wrongly diagnose these traps as being defective, possibly even replacing a good trap and still not getting the desired results. Frustrating! Because the trap has no differential pressure due to the pressurized condensate line, there is also the possibility of water hammer occurring in the heat transfer device that cannot drain. Again, the mixing of steam and condensate can cause water hammer.

Higher Steam Temperatures Problems
This is not the last of the problems that a trap passing steam can cause. With steam passing through the trap, the return condensate is at a higher temperature, which sounds like we are saving energy by not having to add as much sensible heat to the condensate to bring it back up to saturation conditions. But the warmer the condensate is, the more flash steam. Even worse, the pumps will handle hotter condensate, and this can have a negative effect on the pump seals (Viton seal will only help in the short run). And, the higher the temperature, the less NPSH (Net Positive Suction Head) we will have available at our pump suction. Less NPSH available, increases the chance for cavitation to occur in our pump.

Impeller destroyed by cavitation

So, the indirect cost of a trap passing steam may be great. The best solution is to under­stand the operation of your traps, survey and test them on a regular basis, and repair or replace the traps when they fail. The cost will always be justifiable.

The next time you have problems, look at the whole system. Remember that even if the process is still working, a bad trap may actually cause other, more serious problems.

To determine if the trap failed to open may require some special tools and some experience.
1. Start your work with a plan. (It is always a good idea to have plan).
2. Use tags to identify traps
3. Form to record trap data

You will need to have test equipment. Thermometer (You can use an Infrared Thermometer), stethoscope or ultra-sound. Now you can start your traps testing.

Make sure the steam system is on. Use a thermometer to measure the inlet and outlet temperature. If the trap failed to open the temperature reading will be the same. Use a stethoscope or ultra-sound device to listen for steam blowing through trap. If a trap failed to open it will have a low pitch whistle. A steam trap working correctly will have a wet gurgling sound.

Below you can see typical trap installation. If your installation is equipped with a Test and Pressure Relief  Valve you can use it to determine what passing traps steam or condensate.

For help with any steam problems, contact your local Bell & Gossett sales representative. They have the answers to all of your questions.
http://bellgossett.com/sales-service/

Click here to download the October 2019 SteamTeam pdf file

The post When a Steam Trap fails to open appeared first on Xylem Applied Water Systems - United States.

Volume 7/ Issue 1/ January 2020

This article is intended to simplify the selection of components for a steam heating system. The majority of steam boilers used in heating systems are rated on the BTU heat output. Selections are based on modern steam boilers, many older steam boilers had sufficient water storage capacity to fill the heating system with steam and then wait for the condensate to return. Modern steam boilers have much less usable water capacity that can cause boiler flooding or low water conditions to occur.

The tables recommend that a boiler feed unit should be used on all boilers over 300,000 BTU. The boiler feed receiver then becomes the reservoir for the system. The net usable storage capacity of the boiler feed receiver should be between 10 and 20 minutes. The minimum capacity shown in the tables is 10 minutes. Single level buildings that are spread out over a large area should be increased to 15 or 20 minutes.

The Xylem “Steam Team” includes a wide range of steam products. When it comes to expanding, upgrading or repairing your steam system it pays to have a partner like Xylem. We make the parts. We build the system, and we know them inside and out.

Our “Steam Team” representatives are experts in steam heating systems and have the answers you need to get the job done right. They’re the only ones that handle a full line of products that include Domestic Pump condensate handling equipment, Hoffman Specialty air vents, supply valves and traps, and McDonnell & Miller boiler controls. Consult your local representative for more information.

Piping layout and suggested product for one pipe gravity return systems based on system size

Gravity Return Systems

• All steam boilers are shipped from the factory with aLWCO. This could be a 67 or a ‘PSE’ unit, which you can specify when ordering the boiler.
• A 47-2 feeder/LWCO could be installed in place of the factory supplied LWCO on boilers less than 250,000 BTU.
• For boilers over 250,000 BTU, the factory supplied LWCO should be left in place as a secondary LWCO when installing a 47-2 or 51-2 feeder.
• Voltages of feeders, 101A and WFE Uni-Match, should be the same as the voltage at the LWCO cut-off they are being controlled by. For example, purchase and install a WFE-24 for installation on a boiler with a PSE-802-24 LWCO.
• The 67, 64 or series PSE-800 LWCO operates the electrical make-up water feeder and serves as a LWCO.
• We recommend that systems with 10 horsepower or larger boilers use a boiler feed unit.

Piping layout and suggested product for one pipe pumped return systems based on system size

Pumped Return Systems

• All steam boilers are shipped from the factory with a LWCO. This could be a 67 or a ‘PSE’ unit, which you can specify when ordering the boiler.
• A 47-A Pump Controller/LWCO can be installed in place of the factory supplied LWCO on boilers less than 250,000 BTU. The 42S-A is connected to the boiler utilizing the sight glass tappings.
• For boilers over 250,000 BTU, the factory supplied LWCO should be left in place as a secondary LWCO when installing a pump controller/LWCO such as the 42S-A (sight glass tapping installation) or 42S (equalizing pipe installation).
• For any motor larger than 1/3 HP, a motor starter should be used to stop/start the pump to prolong the life of the switches in the M&M pump controller.
• The boiler feed units are selected for 10-minute storage, some applications may require a larger tank. Horizontal units are also available which provide a lower inlet connection.

Piping layout and suggested product for two pipe gravity return systems based on system size

Gravity Return Systems

• All steam boilers are shipped from the factory with a LWCO. This could be a 67 or a ‘PSE’ unit, which you can specify when ordering the boiler.
• A 47-2 feeder/LWCO could be installed in place of the factory supplied LWCO on boilers less than 250,000 BTU.
• For boilers over 250,000 BTU, the factory supplied LWCO should be left in place as a secondary LWCO when installing a 47-2 or 51-2 feeder.
•  “A” Dimension. Pressure Drop + Static Head + Safety Factor. Typically 26-28”.
•  Voltages of feeders, 101A and WFE Uni-Match, should be the same as the voltage at the LWCO cut-off they are being controlled by. For example, purchase and install a WFE-24 for installation on a boiler with a PSE-802-24 LWCO.
•  The 67, 64 or series PSE-800 LWCO operates the electrical make-up water feeder and serves as a LWCO.
•  We recommend that systems with 10 horsepower or larger boilers use a boiler feed unit.

Piping layout and suggested product for two pipe pumped return systems based on system size

Pumped Return Systems

• All steam boilers are shipped from the factory with a LWCO. This could be a 67 or a ‘PSE’ unit, which you can specify when ordering the boiler.
• A 42S-A Pump Controller/LWCO can be installed in place of the factory supplied LWCO on boilers less than 250,000 BTU. The 42S-A is connected to the boiler utilizing the sight glass tappings.
• For boilers over 250,000 BTU, the factory supplied LWCO should be left in place as a secondary LWCO when installing a pump controller/LWCO such as the 42S-A (sight glass tapping installation) or 42S (equalizing pipe installation).
• For any motor larger than 1/3 HP, a motor starter should be used to stop/start the pump to prolong the life of the switches in the M&M pump controller.
• The boiler feed units are selected for 10-minute storage, some applications may require a larger tank. Horizontal units are also available which provide a lower inlet connection.

Domestic pump and Hoffman Specialty pump has a complete line of condensate transfer pumps, boiler feed pumps and vacuum return units

Quick selection materials list with part numbers and description.

Xylem offers the most complete line of products needed for steam systems. The SteamTeam includes Bell & Gossett Domestic Pump, Hoffman Specialty and McDonnell & Miller.

Domestic Pump and Hoffman Specialty
Provides the full line of condensate transfer equipment including condensate transfer units, boiler feed units, vacuum heating units, clinical vacuum units and low NPSH pumps.

Hoffman Specialty
Offers a complete line of steam traps, regulators, vents and accessories.

McDonnell & Miller
Delivers reliable performance and safety in boiler and level control products for over 95 years.

Click Here to download the January 2020 SteamTeam Newsletter

The post Low Pressure Steam Heating System Application and Selection Guide for Residential and Commercial Systems appeared first on Xylem Applied Water Systems - United States.

The new Bell and Gossett e-HSC pump boasts an advanced seal chamber design. This paper outlines the benefits in reduced downtime this technology provides in water applications.

The seal is undoubtedly one of the most important parts of a centrifugal pump. Of course there are many critical aspects of pump performance, but when it comes to mean time between failures, it remains that 60% to 70% of centrifugal pump maintenance is seal related (Lobanoff & Roass, 1985). The fact that mechanical seals can only be replaced once the pump has been shut down (and in many cases drained) also means that this can be an expensive repair, depending upon timing.

Pump and seal design must adequately address the potential for abrasive particles which may shorten seal life due to seal face erosion or seal cavity clogging (Shiels, 2004). Double suction pumps, which historically relied on packing as the primary sealing option, transitioned to mechanical seals to eliminate the fluid leakage and the increased power consumption related to gland packing. However, with that transition came the increased seal replacement time, placing even more emphasis on mechanical seal life. Many designs continue to use a stuffing box capable of accepting either packing or a mechanical seal.

Plans for maintaining seal chamber conditions have long been standardized by the American Petroleum Institute (API) in their Annex G piping plans. Figure 1 provides details behind the plans typically employed in water applications. Plan 02 and Plan 11 are not effective at limiting contaminant buildup and seal wear. Plan 31, however, flushes utilizing pump discharge pressure and filters utilizing a separator in order to limit contamination. While a stuffing box design allows for handling many industrial process fluids because of the flexibility to employ even more complex plans such as 32, 41, or 53, there are more effective and less complicated approaches for water applications. An API plan 31 needs to consider a balance between seal cavity pressure and flush cooling flow through sizing the throat bushing and adjusting the flush orifice (Shiels, 2004). This can be more of a challenge considering the variable flow and pressure in today’s variable speed environment.

Figure 1
American Petroleum Institute seal plans typically seen in water applications
(extract from Flowserve FTA160eng Rev 9-17)

In May of 2014 the American Petroleum Institute amended Annex G piping plans to include a tapered bore seal chamber (Plan 03). This was the result of successful application of large bore tapered seal chambers in extending seal life without the complexity of pressurized flush and particle separation. In fact, an extensive study comparing the traditional Plan 02 stuffing box configuration with a variety of enlarged and tapered seal chambers was conducted for the Tenth International Pump Users Symposium with the expressed purpose of improving the uptime of centrifugal pumps. The study concluded that tapered or flared bore chambers without throat restriction allowed for maximum heat transfer with the pumped product, reduced gas in the seal chamber under start/stop conditions and reduced solids concentrations without the need for external flushing (Adams, Robinson, & Budrow, 1993). The study further found that “some form of rib, strake, or protrusion extending axially along the chamber wall could reduce the high azimuthal velocity and impart an inward radial velocity to the particles…this change in velocity and direction would then allow the particles to exit the chamber with the outflow” (Adams, Robinson, & Budrow, 1993). The study was focused on end suction centrifugal pumps, and it did find that there were some impacts on the effectiveness of the seal chamber design created by impeller features such as balance holes and pump out vanes designed to mitigate axial thrust.

Bell & Gossett has incorporated the best aspects of all these design features into a double suction pump. It has an enlarged tapered seal chamber for internal flush that actually opens into the entire suction chamber of the pump. Due to the balanced thrust inherent in the double suction design, there are no balance holes or pump out vanes adding pressure back into the seal chamber against the flow for particle removal. The seal chamber pressure is dictated by the lower, more consistent suction pressure rather than re-circulated flow from the discharge. There is no need to monitor and adjust external flush pressures or install and maintain particle separators. This design brings more consistent performance and lower install cost than a traditional plan 31. In addition, this stuffing box allows for side access to the seal for faster replacement than traditional stuffing boxes where the upper casing must be removed for seal access. The design even includes an axial rib from the CFD (computation fluid dynamics) model to impact the radial velocity of the particles just as the study indicated. Pump downtime is ultimately best reduced by this type of focus on advanced design that increases mean time between failures and reduces repair times on the number one reason for pump failure.

In the above cutaway photograph of the mechanical seal chamber you can see the tapered bore which opens into the suction chamber of the pump. You can also see the axial rib above the seal that impacts the flow within the suction chamber.

Adams, W. V., Robinson, R. H., & Budrow, J. S. (1993). Enhanced Mechanical Seal Performance Through Proper Selection and Application of Enlarged-Bore Seal Chambers. 10th International Pump Users Symposium (pp. 15-23). College Station, Tx: Texas A&M University.

Lobanoff, V. S., & Roass, R. R. (1985). Centrifgual Pumps Design and Application. Houston, TX: Gulf Professional Publishing.

Shiels, S. (2004). Hidden Dangers in Centrifugal Pump Specification: Part One. In S. Shiels, Stan Shiels on Centrifugal Pumps: Collected articles from “World Pumps” magazine
(p. 275). Oxford, UK: Elsevier Advanced Technology.

Click here to download the pdf

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About Xylem
Xylem (XYL) is a leading global water technology company committed to developing innovative technology solutions to the world’s water challenges. The Company’s products and services move, treat, analyze, monitor and return water to the environment in public utility, industrial, residential and commercial building services, and agricultural settings. With its October 2016 acquisition of Sensus, Xylem added smart metering, network technologies and advanced data analytics for water, gas and electric utilities to its portfolio of solutions. The combined Company’s nearly 16,000 employees bring broad applications expertise with a strong focus on identifying comprehensive, sustainable solutions. Headquartered in Rye Brook, New York, with 2015 revenue of $3.7 billion, Xylem does business in more than 150 countries through a number of market-leading product brands. The name Xylem is derived from classical Greek and is the tissue that transports water in plants, highlighting the engineering efficiency of our water-centric business by linking it with the best water transportation of all – that which occurs in nature. For more information, please visit us at www.xylem.com.

The post The Benefits of Advanced Seal Chamber Design in Double Suction Pumps appeared first on Xylem Applied Water Systems - United States.

The newly designed Bell & Gossett e-HSC pump standardized on a stainless steel shaft and impeller. This paper outlines the benefits of stainless steel in performance and product life.

In 2014 Bell & Gossett launched modernized versions of its Series 1510 base mounted end suction centrifugal pumps. This began the “Power of e” campaign and the “e” designation denotes improved performance characteristics. Since then there has been a re-design of the inline pumps and most recently the horizontal split case pump. Each of these re-designs utilized computational fluid dynamics (CFD) analysis to optimize efficiency and minimize net positive suction head requirements (NPSHR). Most recently, Bell & Gossett launched the e-HSC pump, which broadened and standardized the horizontal split case line while incorporating the latest design technologies.

Another key enhancement to all of these pumps has been the transition from bronze to 304SS impellers. Bronze had been the industry standard for many years based on economics and manufacturing technologies available at the time. Although bronze performs adequately, stainless steel has always been the superior material. The widespread use of stainless steel was cost prohibitive and the manufacture of stainless steel impellers was possible only in specialized facilities working on custom projects. Mass production of these components was not an option. Stainless steel was reserved for only the most demanding applications for this reason. Advances in manufacturing technology and reduced costs for stainless steel material versus bronze have finally made stainless steel use possible on a widespread basis.

In clean water applications bronze remains a suitable choice, but bronze does not offer the same corrosion resistance properties of stainless steel and has a greater potential for degradation. Over time the surface characteristics of bronze can cause it to wear faster than stainless steel – leading to reduced pumping efficiency.

Figure 1
Impeller eye of a bronze sand cast double suction impeller with vane cleanup (left) compared to a stainless steel investment cast impeller (right).

The common bronze alloy used in impellers is especially susceptible to a process called dezincification in which chlorine dissolves the zinc material (4-12% of volume) from the metal. There are specialty grades of bronze with comparable corrosion resistance to stainless, but they are higher cost and harder to manufacture.

The stainless steel impellers are made as “investment castings1 ”. These are created using a lost-wax process that results in a significantly improved surface and part quality than the more common die-cast process or the sand-cast process historically used on bronze casting. The end results of this process are greater efficiency, consistency between impellers, greater durability and more sustainable hydraulic performance. As shown in figure 1, a sample sand cast impeller (left) typically require grinding to address surface imperfections. Investment cast impellers (right) have cleaner edges and a more consistent surface. Impeller performance is not only dictated by the geometric design, but performance enhancements based on surface improvements can also be modeled (figure 2). In order to offer both stainless and bronze impellers, two sets of tooling would be required. By making stainless steel the standard offering and leveraging economies of scale, the benefits of stainless steel are available for all applications without increased cost.

Figure 2
CFD modeling assists in the design for optimal energy transfer

We can also compare the two materials by the numbers. In figure 3 you can see that stainless steel is equal in strength, but has superior crack resistance when compared with bronze. Data also shows the stainless
steel material to be harder than bronze, resulting in equal or less wear and longer life. Stainless steel also has equal or better corrosion resistance for many fluids. Most importantly, stainless steel has no added lead, eliminating the concerns of lead contamination in the pumped fluid which exists with some bronze materials.

The transition from bronze to stainless steel impellers has leveraged the latest manufacturing technologies and offers the power savings, corrosion resistance and reduced wear of stainless steel without the cost penalties that kept this out of reach in the past.

Figure 3

1 Available on impellers up to 18”

Click here to download the pdf

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About Xylem
Xylem (XYL) is a leading global water technology company committed to developing innovative technology solutions to the world’s water challenges. The Company’s products and services move, treat, analyze, monitor and return water to the environment in public utility, industrial, residential and commercial building services, and agricultural settings. With its October 2016 acquisition of Sensus, Xylem added smart metering, network technologies and advanced data analytics for water, gas and electric utilities to its portfolio of solutions. The combined Company’s nearly 16,000 employees bring broad applications expertise with a strong focus on identifying comprehensive, sustainable solutions. Headquartered in Rye Brook, New York, with 2015 revenue of $3.7 billion, Xylem does business in more than 150 countries through a number of market-leading product brands. The name Xylem is derived from classical Greek and is the tissue that transports water in plants, highlighting the engineering efficiency of our water-centric business by linking it with the best water transportation of all – that which occurs in nature. For more information, please visit us at www.xylem.com.

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Volume 6/ Issue 2/ August 2019

There are both legal, and practical considerations that create the need to install mechanical or electronic low water cut-off (LWCO) control on a residential hot water boiler. From the legal side, jurisdictions have adopted codes which state when an LWCO must be installed, while the practical side is based upon system conditions.

ASME (American Society of Mechanical Engineers)
ASME Boiler and Pressure Vessel Code (BPVC) have been universally adopted as the minimum requirement for the manufacture, installation and maintenance of boilers. Section I, for Power Boilers, requires low water protection. Steam heating boilers of any size, regardless of where they are installed, must have a low water cut-off per ASME BPVC.IV. The same code only requires that hot water boilers with input greater than 400,000 btu must have a low water cut-off. In lieu of an LWCO, coil type boilers above 400,000 btu input, which require a flow of water to prevent overheating, shall have a safety device (typically a flow switch) to prevent burner operation when the flow of water is inadequate.

ASME CSD-1 (Control and Safety Devices)
CSD-1-2018 is an additional ASME standard for Controls and Safety Devices for Automatically Fired Boilers. As per Section 4, CSD-1 Part CW-120a requires at least one LWCO on all steam boilers, however the requirement for hot water boilers (Part CW-130a) have exception for residential boilers.

IMC (The Internal Mechanical Code)
This is a newer standard that is being adopted by jurisdictions. It is a consolidation of codes written in the past by BOCA, SBCC, and other independent code councils. Section 1007.1 of the IMC states “All steam
and hot water boilers shall be protected by a low water cut-off control.” If it’s a hot water boiler, it must have a low water cut-off.

2014 New York City Construction Code
SECTION MC 1007 BOILER LOW WATER CUT-OFF  1007.1 General.
All steam and hot water boilers shall be protected with dual low water cut-off control.
Exception:
Hot water boilers located within a dwelling unit supplying only that unit and having a total heat input of less than 350,000 Btu/h (1025 kW) may be protected by only one low water cut-off control.

The Reducing Valve
There has always been a controversy about whether to keep the fill valve open or closed after initially filling a hot water heating system. Bell & Gossett recommends closing the fill valve. If the valve is closed and there is a leak in the system, no water is added to the system which may cause damage to the boiler and flooding. Also a fill valve has a strainer, debris (sand, silt, minerals, rust, etc.) that is present in the water can clog the strainer. If the strainer is clogged, an open valve is no guarantee that water will flow, but if it does, a flood could result. The best practice in a hot water system is to fill the system, close the valve and install a low water cut-off to protect the system.

Piping Elevation
Some systems have piping for radiators, snow melt, and tankless water heaters below the minimum safe water level of the boiler. Boiler manufacturers and organizations such as the National Fuel Gas have recognized this. Each has added a section in their literature or standards that indicates that if a hot water boiler is installed above level of radiation, then a low water cut-off should be installed

For many years, industry leaders have identified the need for low water cut-offs on hot water boilers. They agreed that the only way to detect a low water condition is with a low water cut-off device. No other safety device can determine if water is present. In 1997, McDonnell & Miller introduced the Series RB line of probe type low water cut-offs. Designed for use in residential hot water boiler applications, they feature a green “power on” LED, a “low water condition” red LED, and high sensitivity for use in a water, and water-glycol mixture. The series RB are equipped with a self-cleaning probe for years and years of worry free protection. The Series RB can be installed in either the boiler tapping or supply riser and are easy to wire. They are an excellent choice as the device to sense a low water condition in a hot water boiler. Remember, even with the many other safety devices (temperature limits, pressure relief valves, flow sensors, etc.) installed on a hot water boiler, the low water cut-off is a low cost component which will protect the boiler and system from damage if a low water condition occurs.

Give your customer and yourself peace of mind, and install low water cut-off. It is a low cost way to protect property, health, and even life.

Since 1924 McDonnell & Miller company is protecting boilers in the USA and oversees from dry fire and offers many excellent mechanical and electronic low water cut-offs for hot water boilers.

Our featured electronic controls provide two different versions, based upon the power supply.

McDonnell & Miller RB-122E low water cut-off for residential hot water boilers is an excellent choice for oil or gas hot water boilers with 120V burner circuit.

RB-122-E Low Water Cut-Offs

• For residential and commercial applications
• Electronic operation
• Easy to install and wire
• Red LED indicating low water condition
• Green LED indicating power is on
• Test button
• Automatic reset
• No blow down required
• 20,000 ohms probe sensitivity
• Maximum ambient temperature 120°F (49°C)
• Maximum water temperature 250°F (121°C)
• Maximum water pressure 160 psi (11.2 kg/cm2)

For more information regarding Series RB-122E MM-238REVO.pdf

For more information regarding Series RB-24E please visit our website or download the pdf files MM-288C.pdf and MPF-009B RB 24E.pdf.

If you have additional questions regarding McDonnell & Miller products please see our website or contact our factory representative for your area mcdonnellmiller.com.

Click here to download the August 2019 SteamTeam pdf file.

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