In the hopes of spurring utilities to offer rebates on multiple-speed replacement motors, the Independent Pool & Spa Service Association conducted a study examining the performance of these components.
Some utilities currently grant rebates for multi- and variable-speed pumps, but replacement motors with the same capabilities do not generally qualify. Recently the Public Utilities Commission, the California Energy Commission and investor-owned utilities chose not to include replacement motors in their programs.
“We hope … to demonstrate with our data that it’s to everyone’s advantage to allow these manufactured replacement motors to be eligible for rebates,” said Bob Nichols, one of the IPSSA members who coordinated the study.
According to Nichols, consumers can save approximately $300 by replacing a motor rather than the complete pump, making them a more economical option for those seeking to save energy and earn rebates.
In addition, the organization plans to help its members educate homeowners on how much money they can save by using the motors.
IPSSA performed the study at the facilities of the International Association of Plumbing and Mechanical Officials (IAPMO) multi-speed replacement motors and one multi-speed OEM pump were observed. In addition, IPSSA took data on the performance of three pieces of equipment to serve as a baseline for comparison. Two single-speed motors, one with a nameplate rating of 1 horsepower and the other ¾ horsepower, were compared with the multispeed replacement motors to see if the latter saved energy. The group also wanted to see how the replacement motors stacked up against a 3hp multispeed pump already approved by the California Energy Commission.
The multispeed motors were each tested with 1- and 2hp impellers to see how much of a difference that would make.
To replicate field conditions as much as possible, the pumps were plumbed with 2-inch PVC pipe and the system was configured to establish 50 feet of head.
One of the more crucial sets of data compared the “energy factor” of each pump and motor. This number is yielded by multiplying the gallons per minute times 60, then dividing it by the wattage. The higher the number, the more efficient the system. Both single-speed pumps came in with energy factors of less than 3.
The highest energy factors came from the multispeed motors and pumps at speeds low enough to generate 40 gallons per minute. The already-approved multispeed pump came in at 11.91 — the highest rating. The replacement motors also had high showings, ranging from 9.18 to 10.01. The energy factors were approximately half a point higher when the 2hp impeller was used rather than the 1hp.
The study also showed that when run at the lower speed, the multispeed motors moved from 3.3 to 3.8 times the gallons per watt than did the single-speed pumps, but slightly less than the multispeed pump.
In addition, IPSSA estimates from the study data that a 15,000-gallon pool could go from 5.41 kilowatt hours to 1.47 kilowatt hours when moving from a single-speed 1hp pump to a multispeed replacement motor operated at 40 gpm.