Since single-speed pumps cannot change their flow rates, for normal filtration purposes (the primary purpose of the pump), they are providing far greater circulation than the filtration system needs.
Switching to a variable-speed pump, and operating it at the lowest flow rate while providing adequate filtration, will significantly lower the energy usage, thus saving money.
To convince pool owners of the merits of switching pumps, it’s useful to determine the potential financial savings possible.
A standard, traditional single-speed pool pump is typically 1½ to 2 horsepower and operates using a singlespeed induction motor to generate motor speeds of 3,450 revolutions per minute, resulting in a flow rate of 87 gallons per minute. The power necessary to accomplish that amount of flow is approximately 2 kilowatts.
Using these values, we can calculate the savings for a 15,000 gallon pool running for 6 hours a day.
At this rate, the single-speed pump consumes 12 kilowatt hours. The price of electricity varies by region, but using a value of 16 cents per kWh, a singlespeed pump costs about $700 per year.
Because of the pump affinity law, lower flow rates lead to greater energy savings.
For the same pool, set at 30 gpm, and drawing 300 watts of power running at 10 hours per day, a years’ use of a variable-speed pump would cost $175. That’s a savings of $525 per year!
All of this is assuming that the pool owner is operating their single-speed pump for the necessary period of time.
It’s important to determine the actual amount of time that the pump is used to get a true idea of the real savings. This can be done by asking the pool owner or reviewing the timer.
The math shows that the energy savings are real.
While it is true that variablespeed pumps are more costly than the traditional pumps, many manufacturers advertise that the money can be recouped in roughly 3 years.
As an added bonus, many utility companies offer rebates and other incentives for converting to energy efficient variable-speed pumps. This can lead to hundreds of dollars in savings. Considering that on average a variable-speed pump costs around $1,000, incentives such as these sure make these pumps even more attractive.
