Heat Pump vs Gas Pool Heater: Which Costs Less?
The honest answer: it depends on how you swim, and the deciding question is "steady schedule or on demand?" Here is the full cost math, upfront and monthly, so you can answer it for your own pool.
How each one works (and why it matters)
A gas heater burns natural gas or propane and dumps the heat into your water. It makes heat, so its output is huge (typically 250,000 to 400,000 BTU/hr) and independent of weather.
A heat pump does not make heat, it moves it, pulling warmth out of outdoor air the way an air conditioner in reverse would. Moving heat is far cheaper than making it: for every unit of electricity consumed it delivers 4 to 6 units of heat (a COP of 4 to 6). The catch is modest output (110,000 to 140,000 BTU/hr) that shrinks as the air gets cold.
The money, side by side
Typical installed prices and running costs at average US energy rates:
| Heat pump | Natural gas | |
|---|---|---|
| Installed cost | $4,000 to $7,000 | $2,500 to $4,500 |
| Monthly cost, steady heating* | $150 to $250 | $400 to $700 |
| Heat-up speed (15k gal) | ~0.5°F per hour | 1 to 2°F per hour |
| Works in cold air | Down to ~45 to 50°F | Any temperature |
| Typical lifespan | 10 to 15 years | 7 to 12 years |
*Holding a 512 sq ft uncovered pool about 10°F above air temperature. Your state's energy prices move these numbers a lot, in expensive-electricity states gas closes most of the gap, in cheap-electricity states the heat pump wins by even more. Run your own state and pool size through the pool heating cost calculator to see all four fuel options priced with your local rates.
The break-even math
The heat pump costs roughly $2,000 more upfront and saves roughly $250 to $450 per month of steady heating. That is a 5 to 8 month payback in actual heating months, if you heat all season, the heat pump pays for its premium inside the first year or two. If you only heat a handful of weekends a year, the savings never accumulate and gas's lower price plus instant heat wins.
Decide by swim pattern
- Heat all season on a schedule (most families, FL/TX/AZ pools, swim lessons): heat pump, it is not close.
- Heat occasionally on demand (weekend hosts, vacation homes, northern shoulder seasons): gas. Paying $30 to heat up for one great Saturday beats owning an expensive heat pump that needed to start Thursday.
- Spa attached to the pool: gas, or gas plus heat pump. Nobody wants to wait 3 hours for a hot tub.
- Cold-climate season stretching (opening in April, closing in October up north): gas, or a cold-climate-rated heat pump if you accept slower recovery.
Whichever you buy, buy a cover first
Most of a pool's heat leaves as evaporation from the surface, the same physics in the evaporation calculator. A $200 solar cover cuts heating costs 50 to 70 percent, which shrinks the required heater size, the monthly bill, and even the gap between the two technologies. It is the highest-return heating purchase available, ahead of the heater itself.
Frequently asked questions
How much faster does gas heat a pool than a heat pump?
A common 400,000 BTU gas heater delivers roughly 3 to 4 times the heat output of a typical 110,000 to 140,000 BTU heat pump. On a 15,000 gallon pool, gas can raise the water 1 to 2 degrees per hour; a heat pump manages roughly half a degree. Weekend-only heating from cold is gas territory.
Do heat pumps work in cold weather?
Standard pool heat pumps extract heat from outdoor air and lose capacity as it cools; most become inefficient or shut down below roughly 45 to 50°F. They are ideal for extending the season in spring and fall, not for heating through a northern winter. Gas output does not care about air temperature.
What is COP on a pool heat pump?
Coefficient of performance: units of heat moved per unit of electricity consumed. A COP of 5 means $1 of electricity delivers $5 worth of heat. Ratings of 5 to 6 are measured in warm humid air; real-world COP drops as air cools, which is why shoulder-season performance matters more than the brochure number.
Is solar pool heating better than both?
On operating cost, yes, sunshine is free and panels sip only pump power. The tradeoffs are upfront cost ($3,000 to $7,000 installed), roof or rack space, and no on-demand control: solar gains 5 to 10 degrees on sunny days but cannot hit a setpoint on a cloudy weekend. Many owners pair solar for baseline warmth with gas or a heat pump for control.