Heat pump vs gas pool heater
Gas costs about two and a half times as much to run and gets there in about a fifth of the time. That is the whole decision.
Quick picks
Both heaters plus the cover that makes the slower one viable.
| # | Product | Best for | Price |
|---|---|---|---|
| 1 | No photo Best if you hold a temperature Hayward HeatPro Pool Heat Pump $10.75 per million BTU delivered. Cheapest controllable heat there is. | Lowest running cost per degree when you want real temperature control | |
| 2 | No photo Best if you heat on demand Raypak Digital Natural Gas Pool Heater $28.36 per million BTU, and roughly 2.3x the speed. Buy the speed if you need it. | Heating fast and occasionally, rather than holding a temperature | |
| 3 | No photo Changes the answer Sun2Solar 1200 Series Crystal Clear Solar Cover Cut the overnight loss and a heat pump's slowness stops being a problem. | Most pools, most budgets — the default recommendation |
#ad We earn a commission if you buy through this link, at no extra cost to you. It never changes the ranking. How this site is funded. Prices last checked September 2, 2026.
The two numbers
| Heat pump | Natural gas | |
|---|---|---|
| Cost per million BTU delivered | $10.75 | $28.36 |
| Cost of this heat-up | $17.91 | $47.24 |
| Typical time | About 12 hours | About 5 hours |
| Rated by | Heat OUTPUT | Fuel INPUT |
| Performance in cold air | Falls off | Unaffected |
| Purchase price | Higher | Lower |
| Install requirement | Electrical circuit | Gas line sized for it |
Running costs from EIA US average residential prices (June 2026) with our stated assumptions: COP 5.0 for the heat pump, 82% thermal efficiency for gas. Times assume a 140,000 BTU/hr output-rated heat pump and a 400,000 BTU/hr input-rated gas heater.
So gas is about 2.6 times the running cost and about 2.3 times the speed. Everything else is detail.
Why the running-cost gap exists
It is not about fuel prices. Per unit of energy purchased, natural gas is much cheaper than electricity — about $23.25 per million BTU against $53.75. The reversal happens entirely at the equipment.
| Natural gas bought: $23.25 per million BTU | |
| ÷ 82% thermal efficiency | = $28.36 delivered |
| Electricity bought: $53.75 per million BTU | |
| ÷ coefficient of performance 5.0 | = $10.75 delivered |
A heat pump moves heat rather than making it, and that is worth more than the fuel price gap
A gas heater cannot exceed 100% efficiency because it is converting fuel into heat. A heat pump is not converting anything — it is moving heat that already exists in the outside air into your pool, which is why its effective efficiency is 500% rather than 82%.
The one question that decides it
Do you hold a temperature all season, or heat a cold pool on demand?
Holding a temperature → heat pump. If the pool is warm from May to September and the heater is topping up losses rather than doing big heat-ups, speed is irrelevant and running cost is everything. You are paying the multiple continuously for months, and the heat pump saves it continuously.
Heating on demand → gas. If the pool sits cold and you want it usable on Friday afternoon, twelve hours is a real problem and five is not. You are paying the multiple only on the occasions you use it. Buy the speed.
Cold climate, long shoulder season → gas has an extra edge. A heat pump extracts heat from outside air, so its output and its efficiency both fall as the air cools — which is exactly when you want it in April and October. Gas does not care.
The thing that changes the answer
A heat pump’s slowness only matters if you are doing big heat-ups. A big heat-up is usually needed because the pool lost a lot of heat overnight. And a cover addresses the roughly 70% of that loss DOE attributes to evaporation.
So a cover does not just save money — it makes the cheaper heater viable, by turning “the pool is 8 degrees down and I want to swim this afternoon” into “the pool is 2 degrees down and the heat pump will handle it by lunchtime”. Cover picks here.
What about propane?
Propane is the same heater with a different fuel and it costs about $35.66 per million BTU delivered — roughly 1.26 times natural gas and 3.3 times a heat pump. If you have no natural gas line, propane is what “gas heater” means for you, and the running-cost argument for a heat pump gets stronger.
Whatever the fuel, run it on your own rates before committing: the running cost calculator takes them.
Every pick, in detail
What each one publishes, what is good and bad about it, and — the section this category usually omits — what we could not judge without owning one.
Hayward HeatPro Pool Heat Pump
If you are heating a pool with electricity, this is the shape of machine to do it with. A heat pump moves heat instead of making it, and at the assumptions we publish it delivers a million BTU into the water for about a fifth of what an electric resistance heater costs to deliver the same. It is slower than gas and it fades as the air gets colder, which is exactly when you want it — that trade is the whole decision.
Best for Lowest running cost per degree when you want real temperature control
| Type | Air-source heat pumpThe manufacturer publishes no retrievable specification sheet; figure is as listed at retail. | Retail listing |
|---|---|---|
| Rating convention | Rated by BTU/hr OUTPUTThis is the trap in the category. Gas heaters are rated by fuel INPUT, heat pumps by heat OUTPUT. A 140,000 BTU heat pump and a 140,000 BTU gas heater do not deliver the same heat. | Published standard |
| Cost per million BTU delivered | About $10.75 at our published assumptionsUS average residential electricity at 18.34 cents/kWh (EIA, June 2026) and an assumed COP of 5.0. Both are substitutable on our running-cost calculator. | Our arithmetic |
- Cheapest running cost per delivered BTU of any controllable heater
- No gas line, no combustion, no flue
- Holds a set temperature rather than depending on the weather
- Slow — expect most of a day to move a full-size pool ten degrees
- Efficiency falls with air temperature, so it is weakest in the shoulder season
- High purchase price against a gas heater of comparable output
- The COP this specific unit achieves at your conditions
- Compressor and control-board longevity
- Noise at the distance your deck actually sits from it
These need a unit in hand across a season. We do not have one, so we do not have an opinion worth printing on them.
#ad We earn a commission if you buy through this link, at no extra cost to you. It never changes the ranking. How this site is funded. Prices last checked September 2, 2026.
Raypak Digital Natural Gas Pool Heater
The right answer when speed matters more than running cost — a weekend pool you want warm on Friday afternoon rather than one you hold at temperature all season. At the assumptions we publish, gas costs roughly two and a half times what a heat pump costs per delivered BTU, and it will get there in a fifth of the time. Buy the speed if you need the speed.
Best for Heating fast and occasionally, rather than holding a temperature
| Type | Natural gas or propane fired, digital controlThe manufacturer publishes no retrievable specification sheet; figure is as listed at retail. | Retail listing |
|---|---|---|
| Rating convention | Rated by BTU/hr INPUTA 400,000 BTU gas heater burns 400,000 BTU an hour and delivers roughly 82% of it. Do not compare that number directly against a heat pump's output rating. | Published standard |
| Cost per million BTU delivered | About $28.36 at our published assumptionsUS average residential natural gas at $24.09/Mcf (EIA, June 2026) and an assumed 82% thermal efficiency. | Our arithmetic |
- Fast — hours rather than most of a day on a full-size pool
- Works the same in cold air, unlike a heat pump
- Lower purchase price than a heat pump of equivalent real output
- Roughly two and a half times a heat pump's cost per delivered BTU
- Needs a gas line sized for it, which is often the real cost
- Propane instead of natural gas raises the running cost by about a quarter again
- The efficiency this specific unit achieves in service
- Heat exchanger life against your water chemistry
- Whether your existing gas supply can feed it without an upgrade
These need a unit in hand across a season. We do not have one, so we do not have an opinion worth printing on them.
#ad We earn a commission if you buy through this link, at no extra cost to you. It never changes the ranking. How this site is funded. Prices last checked September 2, 2026.
Sun2Solar 1200 Series Crystal Clear Solar Cover
The value pick, and the one whose logic actually holds up. A clear cover transmits more sunlight into the body of the pool instead of absorbing it at the surface, and 12 mil is the point where lifespan stops being the limiting factor. Bob Vila measured this and the 16-mil blue at the same 4 to 5 degrees in an hour, so you are paying less for the same measured result and giving up some years of service life.
Best for Most pools, most budgets — the default recommendation
| Thickness | 12 milThe manufacturer publishes no retrievable specification sheet; figure is as listed at retail. | Retail listing |
|---|---|---|
| Color | Clear | Retail listing |
| Stated lifespan | 3 to 4 years for the 12-mil clear tierSwim University's published figure for 12-mil clear covers generally. | Retail listing |
| Bubble side | Bubbles face the water | Published standard |
4 to 5 degrees F in one hour
Claimed by Bob Vila, measured across all covers in their group. Conditions: One hour under 2pm sun on 89 to 92 degree F days. Source
- Clear transmits more light into the water instead of stopping it at the surface
- 12 mil is the sweet spot: real service life without 16-mil bulk
- Cheaper than the 16-mil tier with no measured heating penalty
- Shorter published lifespan tier than 16 mil
- A clear cover shows algae and debris more obviously, which some people dislike
- Whether clear genuinely outlasts or under-lasts blue in the same thickness
- Real-world tear resistance at a pool with rough edges
- How much the clear material clouds over a season of UV
These need a unit in hand across a season. We do not have one, so we do not have an opinion worth printing on them.
#ad We earn a commission if you buy through this link, at no extra cost to you. It never changes the ranking. How this site is funded. Prices last checked September 2, 2026.
Questions people actually ask
Is a heat pump cheaper than gas for a pool?
How much slower is a pool heat pump than a gas heater?
Do pool heat pumps work in cold weather?
Which is better for a pool I only use at weekends?
- Average retail price of electricity to US residential customers: 18.34 cents/kWh, June 2026U.S. Energy Information Administration · read 2026-09-02
- US residential natural gas price: $24.09 per thousand cubic feet, June 2026U.S. Energy Information Administration · read 2026-09-02
- US residential propane price: $2.674 per gallon, week ending 30 March 2026U.S. Energy Information Administration · read 2026-09-02
- Energy content conversion factors: 3,412 BTU per kWh, 1,036 BTU per cubic foot of natural gas, 91,452 BTU per gallon of propaneU.S. Energy Information Administration · read 2026-09-02
- U.S. Department of Energy pool-energy figures (evaporation share, BTU per pound evaporated, cover savings, recommended temperatures, wind effect)Recreonics, reproducing and attributing the U.S. Department of Energy · read 2026-09-02
- Pool heater roundup: the 8.33 BTU per gallon per °F figure, attributed on the page to Alicia Toedter of Leslie'sBob Vila · read 2026-09-02
Every URL above was fetched and returned content on the date shown. Where a figure is ours rather than somebody else’s, the arithmetic is on the page and on the methodology page. If you find an error in it, we would genuinely like to know.
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The heat pump running-cost derivation, what happens to it in cold air, and the two inputs that change the answer more than anything else.
What size pool heater do I need?
How to size a heater from your pool's actual energy requirement, the input-versus-output rating trap, and why the answer gets smaller once you own a cover.
How much does it cost to heat a pool?
The complete cost model: what a million BTU costs to deliver with each fuel, what that means per degree and per pool size, and why heat-up cost is not your monthly bill.
How to heat a pool
The complete walkthrough: what your pool actually needs in BTU, every heating option priced per delivered million BTU, and the order to try them in.