Updated October 10, 2026
Choosing a pool heater comes down to three questions: how fast do you need heat, what does energy cost where you live, and how cold does it get? Get those right and the choice usually makes itself.
How each heater type works
Heat pumps
A heat pump doesn't create heat — it moves it. It pulls warmth from the surrounding air and transfers it into your pool water, the same way an air conditioner works in reverse. Because it's moving heat rather than generating it, a heat pump delivers 5–7 units of heat for every unit of electricity it consumes (that's the COP rating you'll see on spec sheets).
Gas heaters
Gas heaters burn natural gas or propane to heat water directly as it passes through. They're brutally simple and brutally fast — a 400K BTU unit can raise an average pool 1–2°F per hour. The tradeoff is fuel cost: you're buying BTUs at retail gas prices.
Solar heaters
Solar panels (usually black plastic collectors on a roof or rack) circulate pool water through sun-warmed tubes. Zero fuel cost, but heating is slow and entirely weather-dependent. A basic kit runs $260–$450 plus installation.
Side-by-side comparison
| Factor | Heat pump | Gas heater | Solar |
|---|---|---|---|
| Upfront cost | $2,000–$3,500 | $1,700–$2,900 | $260–$450 |
| Heating speed | Slow — degrees over hours | Fast — 1–2°F per hour | Very slow — days |
| Monthly operating cost | $50–$150 | $200–$500 | $0 |
| Efficiency | COP 5–7 (500–700%) | 85–95% | Free energy |
| Lifespan | 10–15 years | 8–12 years | 10–20 years |
| Works below 50°F? | Poorly | Yes | Weakly |
| Best for | Warm climates, long seasons | Spas, quick heat, cold snaps | Sunny climates, tight budgets |
The 5-year cost math nobody shows you
Sticker price is misleading. Here's what each type actually costs over five years of regular use:
| Heater type | Purchase | Est. 5-yr operating | 5-yr total |
|---|---|---|---|
| Heat pump (140K BTU) | ~$2,200 | ~$4,500 | ~$6,700 |
| Gas heater (400K BTU) | ~$2,300 | ~$12,000 | ~$14,300 |
| Solar kit | ~$360 | ~$0 | ~$360 |
The takeaway: a heat pump costs roughly half as much over five years as a gas heater doing the same job. Gas only wins the math if you heat rarely — a few weekends a year — where the fuel bill never catches up to the efficiency gap.
Which one should you buy?
- Buy a heat pump if: you live in Florida, Texas, Arizona, Southern California, or anywhere with long warm seasons. You swim regularly and want the lowest monthly cost.
- Buy a gas heater if: you heat a spa, want the pool warm this Saturday, live where spring/fall nights drop cold, or only heat occasionally.
- Buy solar if: you have a sunny south-facing roof, a tight budget, and patience. Or pair it with a heat pump to cut the electric bill further.
- Consider both: plenty of owners run a heat pump for the season and fire up gas for quick spa sessions. It's the premium setup for a reason.
Don't forget sizing
An undersized heater runs nonstop, costs more to operate, and dies early. A 140K BTU heat pump suits most 15,000–20,000 gallon pools; gas heaters are typically 400K BTU for full-size pools. See our heater BTU sizing chart for the full table by pool volume.
Current heater deals
We track heat pump, gas, and solar heater prices daily across three retailers. See today's pool heater deals →
Frequently asked questions
Is a heat pump or gas heater better for a pool?
In warm climates (air temps above 50°F most of the swim season), a heat pump is usually better — it costs 5–7x less to run than gas. Gas heaters win when you need fast heat: weekend warm-ups, spas, or cold climates where heat pumps lose efficiency.
How much does it cost to run a pool heat pump per month?
A typical 140K BTU heat pump costs roughly $50–$150 per month in electricity depending on your rates, pool size, and target water temperature. A comparable gas heater often costs $200–$500 per month in fuel.
Do heat pumps work in cold weather?
Heat pumps lose efficiency as air temperature drops and most struggle below 45–50°F. If you swim in cold weather or heat a spa year-round, a gas heater is the more reliable choice.
Is solar pool heating worth it?
Solar has zero operating cost and the cheapest upfront price ($260–$450 for a basic kit), but it heats slowly — often taking days to raise pool temperature. It works best as a supplement to a heat pump or gas heater, or for pools in very sunny climates.
How long do pool heaters last?
Heat pumps typically last 10–15 years, gas heaters 8–12 years, and solar panel systems 10–20 years. Proper sizing, balanced water chemistry, and winterization all extend heater life significantly.