A variable speed pool pump can dramatically cut your energy usage. When compared with a single stage pump (like I have), the savings are dramatic. Most manufacturers claim that the payback is 1 to 2 years, but that is based on several assumptions, many of which don’t hold true for me personally. So when you look at the sales literature make sure the numbers portrayed actually apply to you.
The sales literature I’m reading is based on comparing a variable speed pump to a 1 ½ horsepower single speed pump running at 12 hours per day. The cost of electricity is $0.16 per kWh. The claim is a cost savings up to $1,500 each year. This would hold true if your costs and run times are the same as the comparison.
I don’t run my pump for twelve hours a day unless the water looks like split pea soup. Otherwise I run it the minimum amount necessary for the water to be clear and the chemicals to stay balanced. So the cost to run my 1hp single speed pump will be less and my purchase decision may be different.
I calculated that the cost to run my pump is $509.52 per year. I arrived at this number by calculating the total number of hours annually that I run my pump and multiplying by my hourly cost of $0.22 per hour.
Hourly cost: Motor Amp Rating x Voltage=Watts (7.4 x 230v=1702watts)
Watts/1,000=Kilowatts (1702/1000=1.702 kilowatts)
Kilowatts x Cost per kWh=Cost per hour (1.702 x $0.13=$.22 per hour)
I calculated my annual run times by taking the number of hours each day I run the motor.
For December through March: 3 hours each day x 120 days=360 hours
For April: 5 hours each day x 30 days = 150 hours
For May: 8 hours each day x 31 days = 248 hours
For June through August: 10 hours each day x 92 days=920 hours
For September through October: 8 hours each day x 61 days=488 hours
For November: 5 hours each day x 30 days=150 hours
Total annual hours=2316 hours x $0.22 per hour=$509.52 annual electricity cost to run my pool motor.
By comparison, if I get a variable speed motor and run it a flat 10 hours per day (although I think the true time would be closer to 15 hours per day), my costs decrease. Using the formulas above: 2.44amp rating x 230v=561.2/1000=.5612 kilowatts
.5612 kilowatts x $0.13 kWh=$.073 x 3650 hours per year = $266.45
So if I installed a variable speed motor, my annual power cost is $266.00 for a savings of $243.00 per year over my current cost. Right now my power company is offering a rebate that would lower my installed cost down to about $1,000.00.
My simple payback is $1,000/$243=4.12 years
There is no doubt the variable speed pump saves energy. Substitute your own numbers for mine to see your own breakeven.