How much electricity does a pool heater use? Get your own answer: enter your wattage, hours of use per day and electricity rate, and press Calculate to see your cost per day, month and year. Those same results also cover pool heater power consumption.
If your pool is the biggest unknown on your electric bill, you are probably asking how much electricity does a pool heater use before you flip the switch for the season. The honest answer is that it depends on the type of heater: a heat pump typically draws a few kilowatts, an electric resistance unit draws several times more, and a gas heater barely touches your meter. This guide gives you the numbers, the formula and a worked example so you can price your own pool.
Every pool heater converts energy into warm water, but they get that energy from different places. Some pull it from your electrical panel, some from a gas line or propane tank, and some from the sun. Your electric bill only reflects the first group, so the first step is knowing which kind of swimming pool heater you own. Related: how much electricity does a coffee maker use.
Power is measured in watts, and 1,000 watts make one kilowatt. A heater's nameplate rating tells you how many watts it pulls while running. The ranges below are common for home pools; always confirm the exact wattage in the user manual or on the data plate.
A residential pool heat pump usually draws about 3 to 6 kilowatts while it runs. It does not create heat by burning anything. It moves heat from the ambient air into your water, which is why it needs so little power for the heat it delivers. If you want the short answer to how much electricity does a pool heat pump use, think of a few kilowatts for several hours a day during heating season.
An electric resistance unit works like a giant water-heating element. Models for pools and spas commonly pull 5 to 15 kilowatts, and every bit of that power becomes heat one-for-one. That is why they are mostly used for a hot tub or small spa rather than a full-size pool.
A gas heater burns natural gas or propane, so the electricity it needs is limited to a control board and ignition. Its real running cost shows up on your gas bill, not your power bill, and it often costs more per hour than a heat pump.
A solar heater collects free heat from the sun. The only electricity involved is your existing circulation pump pushing water through the panels, so its added energy usage is small. It simply does not heat at night or under heavy cloud.
The wattage on the label is the draw while the heater is running. Your pool heater energy usage is that draw multiplied by how long it runs, and run time depends on weather, pool size and the temperature you set. Many pool owners are surprised that two identical heaters on two different pools can post very different monthly totals.
You do not need a special app to price your heater. A simple multiplication does the job, and it is the same method any pool heater energy calculator uses behind the scenes.
$$\text{Daily cost} = \text{Heater kW} \times \text{Hours run} \times \text{Rate per kWh}$$Divide the heater's watts by 1,000 to get kilowatts, then multiply by the hours it runs to get kWh, the unit your utility bills. For example, \(3{,}900 \div 1{,}000 = 3.9\) kilowatts. Run that for 7 hours and you have used 27.3 kilowatt-hours.
Say your heat pump pulls 3.9 kilowatts, it runs 7 hours per day, and your electricity rate is $0.157 per kilowatt-hour.
Swap in your own energy rate from your latest bill and your own run time, and the same math gives you your own answer. Your heating costs will rise in cold snaps and fall in warm spells, so treat the result as a seasonal average rather than a fixed monthly figure.
The reason heat pumps are cheaper to run than resistance heaters is a number called the coefficient of performance, or COP. It is the ratio of heat delivered to electricity consumed. A COP of 5.5 means each kilowatt of electricity moves 5.5 kilowatts of heat into your water. Resistance heating, by contrast, has a COP of exactly 1. Compare with heat gun electricity consumption.
A fan pulls ambient air across an evaporator coil, where refrigerant absorbs the heat and turns into a gas. The compressor squeezes that gas to raise its temperature, and the condenser passes the heat to your pool water. Because the machine transfers heat instead of making it, the electrical input stays modest. An inverter model can also ramp its speed down once the water is warm, which saves further efficiency losses.
Because they depend on outside warmth, heat pumps lose output when the air temperature drops toward the low 50s Fahrenheit. They also heat slowly, so the heating time is longer and they suit consistent use more than a last-minute weekend soak. If you want hot water fast, a gas unit is the better fit, though you will pay more per hour for it.
To compare fairly, you have to compare the same job. Take a 15,000-gallon pool and raise its water temperature by 10°F. Water weighs about 8.34 pounds per gallon, and it takes one BTU to warm one pound by one degree. So the job needs \(15{,}000 \times 8.34 \times 10 = 1{,}251{,}000\) BTU. The table prices that job at $0.157 per kilowatt-hour and $1.32 per therm of natural gas, assuming a 5.5 COP heat pump and an 84% efficient gas unit.
| Heater type | Energy needed | Cost for the job |
|---|---|---|
| Heat pump (COP 5.5) | 66.7 kWh of electricity | $10.47 |
| Electric resistance | 366.6 kWh of electricity | $57.56 |
| Natural gas (84% efficient) | 14.9 therms | $19.66 |
The heat pump delivers the same warmth for roughly one fifth of the resistance heater's electricity cost and about half of the gas cost. An energy efficient heat pump has a higher purchase price, which is paid back through lower operating costs and a longer lifespan, with less maintenance than a gas burner. Gas still wins on speed, since it can heat gallons of water far faster. Prices for propane and natural gas move around, so run the same calculation with your local figures.
If a neighbor's bill looks nothing like yours, one of a handful of factors explains it. Each one changes how many hours your heater must run. Next, look at how much electricity does an angle grinder use.
A bigger pool size holds more water to heat, so run time grows with volume. Your target temperature matters too: every extra degree adds hours, and many swimmers find the low 80s Fahrenheit comfortable. Dropping the setpoint a couple of degrees is one of the quickest ways to shrink the bill.
Evaporative heat loss is the biggest thief of warmth in an open pool. Water leaving the surface carries heat with it, and wind speeds the process up. Shade, a cold climate and cool nights make the heater work longer to replace what escapes.
Mild weather can extend your swimming season by months with very little power, while cold regions need far more run time. Heating only during daytime hours keeps a heat pump working when the air is warmest and its efficiency is highest.
The cheapest kilowatt-hour is the one you never use. These habits reduce heat loss and trim the hours your heater runs.
To work out your own heater's electricity use and monthly running cost, follow these steps.
Once the heater is running, compare your electric bill with last year's same month. The difference is your heater's share. Heat pumps and resistance units need a dedicated electrical circuit, so an electrician will size the breaker from the nameplate. A good cost to run estimate beforehand helps you decide whether the upgrade pays back.
Not sure where to start? Enter your heater's kilowatts, daily hours and rate into any pool heater energy calculator, or use the formula above, and compare the result with your actual run time after a few weeks. Those two numbers keep your energy consumption honest from one season to the next.
Before you buy, weigh each model's installation cost against the long-term savings in electricity, and compare the rated COP from brand to brand, because a higher COP means fewer kilowatt-hours for the same warmth. A solar cover or solar blanket then cuts the hours the heater runs, so the sun's free warmth lowers your running cost further.