Heat Pump vs Gas Pool Heater: Running Cost
Warming a 15,000-gallon pool by 10 °F costs about $23 with an 80% efficient gas heater at $1.50 per therm, and about $12 with a heat pump (COP 5) at $0.17 per kWh. At 20 heat-ups a year, the heat pump saves about $220 in energy at those example prices.
On this page (8 sections)
A heat pump usually costs less to run, and a gas heater usually costs less to buy and heats faster. Which one wins for you depends on your gas and electricity prices, your climate, and how often you heat.
About these numbers. The prices, the 80% gas efficiency, and the heat pump COP of 5 are example values, not national averages. Use the rates on your bills and the ratings of the heaters you are comparing. The math covers the heat-up only. Keeping a pool warm costs more, mostly because of evaporation. Like our other cost calculators, this one is not yet covered by the tested reference cases behind our chemistry numbers.
Calculator: gas vs heat pump for the same heat-up
Both heaters must put the same heat into the water: BTU = gallons × 8.34 × degrees of rise. The energy each one uses is different:
- Gas: therms = BTU ÷ 100,000 ÷ efficiency. In the example, 15.6 therms, or $23.
- Heat pump: kWh = BTU ÷ 3,412 ÷ COP. COP (coefficient of performance) is the heat it delivers per unit of electricity. In the example, 73.3 kWh, or $12.
The difference is $11 per heat-up, and $220 a year at 20 heat-ups like this. Enter your own numbers, including how many times a year you heat the pool from cold. This page compares two heaters. To estimate the cost of running the heater you already have, use the pool heater cost calculator.
Running cost vs the price to buy
The U.S. Department of Energy (DOE) says heat pump pool heaters cost more than gas heaters, but they typically have much lower yearly operating costs and, with proper maintenance, usually last longer. To see when the higher price pays off, enter the installed price of each heater from your quotes. The calculator then shows the payback: (heat pump price − gas heater price) ÷ yearly saving.
We don't list installed prices, because we could not confirm current national figures, and prices depend heavily on gas lines, electrical work, and permits. Get written quotes that include installation.
The heater's size matters too. Use the pool heater size calculator to find the minimum BTU for your pool. The DOE says a trained pool professional should do the sizing.
When gas makes more sense
- You heat only occasionally. The DOE says gas heaters heat pools quickly, which makes them a good choice for pools used only periodically.
- You swim in cool weather. The DOE notes that gas heaters can keep any temperature regardless of the weather.
- Your gas is cheap or your electricity is expensive. Put both rates in the calculator.
Efficiency matters. The DOE says some gas pool heaters now reach 89% to 95%. A higher efficiency in the calculator lowers the gas cost.
When a heat pump makes more sense
- You keep the pool warm all season. Lower running cost adds up over many weeks.
- Your weather is usually mild. The DOE says heat pumps work efficiently while the outside air stays above about 45–50 °F, and lose efficiency in cooler air.
- Electricity is reasonably priced where you live.
The DOE puts heat pump COPs at about 3.0 to 7.0. The federal test uses 80 °F air, 63% humidity, and 80 °F water, so in cool weather the real COP is lower. Enter a lower COP to see a cool-weather case.
Solar heaters: the third option
Solar pool heaters pump water through collectors that the sun warms. In an older version of its solar pool heater page, the DOE said a solar system usually costs $2,500 to $4,000 to buy and install, with a payback of 1 to 7 years depending on local fuel costs and sun. It also said solar heaters typically last longer than gas and heat pump heaters. They depend on sun and on roof or rack space for the collectors.
Cover first, then choose the heater
The DOE calls a cover the single most effective way to cut pool heating costs, with savings of 50% to 70% possible. Evaporation is the largest heat loss, and a cover stops most of it. The DOE adds that a cover can help reduce the size of a solar heating system. Estimate your savings with the solar pool cover savings calculator.
Keep the water balanced to protect the heater's heat exchanger. Calcium or pH out of range can cause scale or corrosion inside it. See calcium hardness. For small pools, see the above-ground pool heater guide.
Gas and electrical safety. Gas heaters need gas piping and venting installed as the maker's manual says, and heat pumps need proper wiring. Hire a licensed gas technician or plumber for gas work and a licensed electrician for wiring, with permits where your local code requires them. The U.S. Consumer Product Safety Commission (CPSC) recommends ground-fault protection (GFCI) on pool equipment, including heaters near the pool on 240-volt circuits.
FAQ
Is a heat pump or a gas heater better for a pool?
It depends on how you use the pool. For season-long heating in mild weather, a heat pump usually costs less to run: in our example, $12 per heat-up against $23 for gas. For fast, occasional heating or cool weather, gas is often the better fit.
Does a pool heat pump work in cold weather?
It works, but less efficiently. The DOE says heat pumps run efficiently while the air stays above about 45–50 °F. Below that, they deliver less heat for the same electricity, so heat-ups take longer and cost more.
How much does a solar pool heater cost?
An older DOE page gave $2,500 to $4,000 to buy and install, with a payback of 1 to 7 years. We could not confirm newer national figures, so get local quotes.
How do I work out the payback of a heat pump?
Payback in years = (heat pump installed price − gas heater installed price) ÷ yearly energy saving. Enter both installed prices in the calculator, and it uses the yearly saving from your heat-ups and rates.
Sources
- U.S. DOE Energy Saver, Heat pump swimming pool heaters (cost, lifespan, COP 3–7, 45–50 °F, test conditions; archived copy, June 2026): energy.gov via web.archive.org
- U.S. DOE Energy Saver, Gas pool heaters (fast heating, any weather, 89–95% efficiency; archived copy, January 2026): energy.gov via web.archive.org
- U.S. DOE Energy Saver, Solar swimming pool heaters (cost, payback, lifespan; archived copy, June 2025): energy.gov via web.archive.org
- U.S. DOE Energy Saver, Swimming pool covers (50–70% heating savings; archived copy, May 2026): energy.gov via web.archive.org
- U.S. EIA, British thermal units (therm = 100,000 BTU; 1 kWh = 3,412 BTU): eia.gov
- U.S. CPSC, Don't swim with shocks (GFCI on pool equipment, including 240-volt heaters): cpsc.gov