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Recent advancements in motor controls have had huge impacts on the circulator pump market. Specifically, circulator pumps with what are known as Electronically Commutated Motors, or ECMs, trigger an intelligent speed control system that provides substantial energy savings. This is because speed-controlled pumps automatically adjust their output to changing demand, whether it’s because of outside temperature, amount of sunlight, overall activity, or other heating sources. The benefit of having a more efficient ECM motor pump comes in substantial energy savings, cost savings, and increased comfort delivery.
Circulators have become up to 80 percent more energy efficient, which has been a boon for the commercial building market. These energy-efficient pumps improve the energy profile of any building without the need for new construction work. In commercial buildings, by simply replacing an existing circulator pump with a new high efficiency one, savings can add quickly. Used to pump domestic hot water, distribute heated, or chilled-water to fan coils or high-efficient chilled beam systems in facilities, the new ECM circulators represent a great savings opportunity.
ECM pump’s higher efficiency in part-load conditions matches the application requirements of buildings as they can automatically react to changing weather and occupancy conditions throughout the year. Realizing a technology shift to a more efficient circulator pump can have a dramatic effect at scale on lowering energy costs, and ultimately for reducing greenhouse gas emissions. By leveraging energy rebate programs effectively, facility managers can realize significant energy and cost-savings.
This technology shift for circulator pumps enables significant performance improvements over permanent split capacitor (PSC) motors, which have traditionally been used. Replacing a PSC-driven circulator with an ECM-driven circulator, facility managers can achieve up to 80 percent savings in electricity. ECMs offer an efficiency step change by their design, which uses permanent magnets in the rotor thereby eliminating traditional PSC motor losses. The efficiency benefits become greater at reduced speeds and loads. Unlike PSC motors, ECMs require integrated electronic circuitry and a variable frequency drive to operate. This is the main reason why they are a bit more expensive, but because it makes them inherently variable speed-capable, they save energy and improve system performance.
Europe has adopted ECMs at a much greater rate than the United States, but the North American market is catching up. One reason is because of a rating system for circulator pumps that provides facility managers the ability to clearly and easily identify the efficiency of a given pump, and its potential for cost-savings. The Energy Rating label was developed by the Hydraulic Institute in conjunction with the major circulator manufacturers and efficiency advocates. It serves as a comparison tool between a conventional PSC base model and a rated high efficiency model, based on the relative energy usage. It can also be used to compare two competitive models or see the savings impact of operating the pump in a more efficient mode. Finally, it helps users identify the savings across a pump’s entire lifecycle. Simply put, the higher the rating, the greater the savings.
In determining a rating, circulator pumps are tested both for their electrical input and hydraulic output powers. Measurements are taken at maximum speeds as well as at reduced speeds based on a pump’s onboard controls. Testing is designed to simulate the variable control modes within ECM circulator pumps, which increase and decrease their speeds based on pressure, temperature, or other system variables. Because ECM pumps can reduce speed and have higher efficiency at lower speeds, the Energy Rating compares their power consumption at reduced speed points versus the full speed points of a typical PSC circulator.
The range reported on the label is similar to the highway and city miles per gallon sticker on a new car. This same concept was adapted and applies to circulators, where the power consumption depends on how they are operated. The Energy Rating of 180, for example, represents the most efficient control method onboard and can be estimated to provide a power savings of 91 watts over the baseline circulator. This estimate is then used to determine the approximate cost-savings based on the average operating hours and cost of electricity in the United States, yielding an annual savings for the pump at $36.30. While this is an estimate, it is based on trusted performance and operating hour data using widely accepted testing criteria. This is a reliable tool for electric utilities to provide purchase incentives to help transition the market, which will reduce energy consumption and carbon emissions in their region. The rating also assists in communicating to the customer the relatively short payoff period and long-term costs savings.
Switching from a traditional circulator pump to an ECM-driven pump with an Energy Rating label certainly yields cost-savings to consumers, but when considered at scale across different industries, it represents both a paradigm shift in technology and a breakthrough in sustainability and in reducing the global carbon footprint.
“Most pumps on the market now have Hydraulic Institute Energy Rating labels, which reflect a given pump’s lab-tested performance,” says Northwest Energy Efficiency Alliance Program Manager Warren Fish. “The Energy Rating label helps pump buyers quickly compare and select their most efficient option—which in many cases is a smart pump. With the ER label, you can see in one number how efficient a given pump is compared to the other models that could meet your system requirements. Knowing that your pump scores well in the ER lab test is important because over the lifetime of owning a pump, the building owner will often pay more for the electricity to operate the pump than what they paid to purchase and install it.”
Transitioning the market to more efficient circulators and onboard controls can offset the CO2 emissions from more than 1 billion gallons of gasoline and save consumers more than $1 billion over the circulators lifetime.
Michael Michaud is Executive Director, Hydraulic Institute.