If you’re running air conditioning in summer, you might assume that’s why your electric bill jumps. But pool filtration also causes a seasonal energy spike.
Pump Motors Matter
Traditional single-speed pool pumps can consume up to 5,000 kWh annually, translating to approximately $450-$500 per year in electricity costs. In contrast, energy-efficient variable-speed pumps can reduce energy usage by 50 to 80 percent. It’s not just the more efficient motor that will cut your costs, however, it’s the “smart” technology many of them have built in. They can be programmed to run at certain times of day, for a certain length of time, at a certain power level.
A slower pump usually runs much more quietly (an added perk), and the moving parts should last longer, although there’s little third-party testing of most models to verify this. One of the decisions you’ll have to make, once you start shopping for a variable speed pump, is whether to spend almost twice as much on a trusted brand such as Hayward or Black & Decker, or pick up a lower cost version, typically an Asian import.
For example, here’s a 2 HP variable speed Black & Decker pump for $1129 on Amazon. You can buy a similar model from XtremepowerUS for $589. Both products claim similar characteristics. The XtremepowerUS ones are made in China. However, if you do a little digging, as I did, you find that the Black & Decker pump is also made in China. So the purchase decision is not an “American made” versus import one.
There’s little data on how long the less expensive pool pumps last, but my advice would be to purchase a good extended warranty if you opt for any of these pumps of 3 years or more. In my experience, Three seems to be the “magic” number when mechanical devices fail or need repair.
The Benefits of Lower RPM
Variable-speed pool pumps utilize permanent magnet motors, similar to those found in electric vehicles.
Key to their advantages is finding the right balance of power and performance—just enough to maintain the pool and no more. There’s an engineering rule of thumb called the pool pump affinity law that offers some insights.
In the table below, which I found at Chlorine King Pools, you can see how even a small adjustment in the motor RPM can have a big impact on power usage. Dropping RPM from 3450 to 3000, for example cuts energy use by almost 50 percent.
How Much Filtration is Enough?
As you size out a pool pump, you’ll be wondering how much power you need. The consensus seems to be that pool water should be fully cycled through a filter once every 6-8 hours. So if you have a 10,000 gallon pool, you only need a flow rate of about 20 gallons per minute (GPM) to cycle it in 8 hours.
Pool pros will be quick to point out, however, that several variables affect the need for filtration. These include the temperature of the water, number of bodies using it, and even the amount of pollen in the air.
It’s safe to say, however, that most home swimming pools are probably dramatically overpowered, wasting energy like crazy. And don’t fall for the hype. Pump manufacturers like to boast about high flow rates, but they’re pushing you into unnecessary consumption.
Some utility companies offer rebates for homeowners who install ENERGY STAR® certified pool pumps. These incentives can range from $100 to $300, depending on your location and utility provider. Even without the rebates, however, the ROI on a pump is substantial. Replacing a single-speed workhorse with a lighter, more nimble variable speed pump should pay for itself in energy savings in a couple of years.
