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Hydronic Systems: New Pump Design Can Help Save Energy

Grainger Editorial Staff

Some of the oldest and most common heating systems used today across North America are hydronic systems, a heat-transfer medium in heating and cooling systems. In large-scale commercial buildings such as high-rise and campus facilities, a hydronic system may include both a chilled and a heated water loop to provide for both heating and air conditioning.

In most hydronic systems, the water is circulated by means of one or more circulator pumps. The system may be broken up into individual heating zones using either multiple circulator pumps or a single pump and electrically operated zone valves.

One of the biggest potential energy drains in a hydronic or radiant heating system is also one of its smallest components: the hot-water circulation pump. Over the last 60 years, the circulation pump design has not changed much in terms of efficiency and design. Although not huge energy hogs, these pumps typically run at fixed flow rates using less than optimal electrical consumption. Sixty years ago, electrical costs were fairly inexpensive, so consideration of energy consumption in the design process was non-existent.

With today’s green movement in industrial and residential buildings, the time for an improved energy-efficient circulator pump was evident.

The Alpha™

What has emerged was an innovative new pump from Grundfos Pumps Corporation that automatically and continuously adjusts circulator performance to the changing needs of the hydronic heating system. Developed in Europe nearly a decade ago, the ALPHA™ is a proven technology with millions of successful, high-efficiency installations there. However, Europe’s hydronic systems are different than those in North America. As a result, the pumping requirements are different, too. The larger systems in North America required larger flow rates, so critical adjustments had to be made to the hydraulic design of the Alpha.™

Energy Savings Achieved

By continuously fine-tuning power consumption and flow rates to meet the dynamic needs of the system, Alpha™ saves both energy and money,” says Bob Reinmund, senior product specialist for Grundfos. “In live field tests of the product, independent contractors have experienced power savings up to 80% over conventional pumps.”

The Alpha™ design focused on three key energy saving opportunities:

Breakthrough motor design – the electronically controlled motor features a magnetized rotor, thus avoiding motor-slippage problems common to induction-type motors. The result is a dramatically more efficient motor that generates less heat and energy waste, while delivering a starting torque four times higher than a standard induction motor – a key feature should the circulator experience long periods of idleness.

No more oversized retrofits – identifying the specific, ever-changing needs of a home heating system can be a challenging task for installers, particularly in retrofit applications. As a consequence, contractors often find it difficult to select the right pump and then to program it with the correct settings. “If the installer is not familiar with piping layout, he may decide the best way to avoid a callback is simply to oversize the pumps,” says Reinmund. The larger pump will use more energy. “Alpha™ creates a colossal opportunity to address this oversizing tendency.”

The installer now has the option of activating the "AutoAdapt function." The circulator will automatically find the lowest possible operating efficiency point to meet changing system demand.” continues Reinmund. “Then it will continuously adjust that setting to achieve optimal comfort at minimal power consumption — all without direct human intervention. The pump can operate with an input as low as five watts, as compared with a minimum of 80 watts for a conventional circulator of comparable size.”

Two-Year Field Testing

To assure that the new ALPHA™ circulator would fully meet the needs of North American hydronic systems and those who design and install them, Grundfos used the past two winters to conduct approximately 200 rigorous field tests with the product across the United States and Canada. Feedback from these field tests has led to important adjustments in the hydraulic design of the Alpha.™

Phillip Hughes is a 50-year veteran of the plumbing and heating contracting business. As owner of Hughes Plumbing and Heating, Inc. of Harrod, Ohio, Hughes has worked on a wide array of residential, commercial and industrial projects over the years. As part of the field testing, Hughes installed a new ALPHA™ into his own home hydronic heating sytem, which features seven zones and a 155,000 Btu per hour, high-efficiency boiler. He kept close tabs on power consumption over the past two heating seasons and now reports that the new circulator “saved in the neighborhood of 55%” over the older circulator model. “The previous circulator was pulling .7 amps and running between 55 and 70 watts during the heating season, “ says Hughes, noting that the ALPHA™ delivered a dramatic reduction of between 7 and 22 watts.

Paul Seward is a mechanical engineer in Louisville, Colorado. Seward installed the new Alpha™ pump into his own home two winters ago, using it as the main distribution pump for his entire household heating system. The ALPHA™ moves warm or chilled water from the heat pump through the various radiant zones, which cover approximately 80% of his two-level structure. The circulator also serves the small section that is heated or cooled with an air handler. “As the valves in the different sections open or close with rising or falling demand, my ALPHA™ automatically ramps up or down to meet the load without any adjustments on my part,” he explains. “It’s pretty much a set-it-and-forget-it proposition.”

According to Seward, the previous circulator pump was a fixed-speed model and it “ran at 100 watts all the time. Meanwhile, the ALPHA has stayed consistently between nine and 13 watts.”

That calculates to an approximate 75% cut in consumption, even at the upper range for the ALPHA. Seward calculates that the impact on his electrical bill for one year would be a savings of around $24. That won’t exactly stop global warming in its tracks, he acknowledges, “but if all the pumps in my system were this efficient, the savings would quickly mount up.”

Besides its flawless performance over the past two heating seasons, Seward also credits the ALPHA for virtually silent performance — a huge plus in any environment, but especially a home. “The circulator has worked so well for me over the past two years,” he says, “I’m looking forward to specifying it in my various company projects as well.”

Ready For Prime Time

With field testing complete in the spring of 2009, the ALPHA™ is now available for the residential and light-commercial North American market. Along with its “big brother” Magna™, designed for the commercial market, hydronic systems across the continent will begin to see the much needed payoff in energy savings.

Information courtesy of Grundfos Pumps Corporation

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The information contained in this article is intended for general information purposes only and is based on information available as of the initial date of publication. No representation is made that the information or references are complete or remain current. This article is not a substitute for review of current applicable government regulations, industry standards, or other standards specific to your business and/or activities and should not be construed as legal advice or opinion. Readers with specific questions should refer to the applicable standards or consult with an attorney.

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