Gas pool heaters worth buying
Buy gas for the speed or do not buy gas. Ranked on published input, on what the makers will say about efficiency, and on the gas line it will take to feed them.
Quick picks
Ranked on published input rating and the efficiency figure each maker is willing to state, on gas demand, and on the cost-per-delivered-BTU arithmetic below — not on testing, which we do not do.
| # | Product | Best for | Price |
|---|---|---|---|
| 1 |  Best overall Raypak Digital Natural Gas Pool Heater 336,000 BTU/hr with a stated 82% efficiency in the listings. About six hours for a full-size pool. | Heating fast and occasionally, rather than holding a temperature | |
| 2 |  Best for the fastest heat-up Pentair MasterTemp 400 Natural Gas Pool Heater The 400,000 BTU/hr class — about five hours — and the one the listings call the quiet one. | A full-size pool heated on demand, when you want the largest gas class | |
| 3 |  Best small gas heater Hayward Universal H-Series 150,000 BTU Natural Gas Heater 150,000 BTU/hr, under half the gas demand. Often the only one an existing gas line will feed. | A modest pool where the gas supply, not the heater, is the real constraint | |
| 4 |  Best propane heater Pentair MasterTemp 400 Propane Pool Heater Same machine, propane burner, about $35.66 per million BTU. Speed is the entire case. | A full-size pool heated on demand, where there is no natural gas | |
| 5 |  Buy this before any of them Sun2Solar 1600 Series Ultimate Blue Solar Cover Every hour a gas heater runs is fuel. A cover cuts the hours by stopping the overnight loss. | An inground pool you cover most nights, every season |
#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 October 17, 2026.
How we judged these
- Published input rating. Gas heaters are rated by fuel burned per hour, not heat delivered. That number sets both the speed and the size of gas line the heater needs, and it is the first thing to check.
- Whether an efficiency percentage is published. The share of that fuel that reaches the water. Some makers state one, some describe it in words. We say which, and we run anything unstated at the 82% we assume for gas.
- Gas demand against a normal residential line. This is the criterion the category skips and the one that most often decides the purchase in practice.
- Heat exchanger material and emissions rating. Cupro nickel is the corrosion-tolerant option; low-NOx certification decides whether a unit is permitted in your air district at all.
- Natural gas or propane. The same heater, a different burner, and about a quarter more per delivered BTU on propane. If you have no gas line, propane is what “gas heater” means for you.
Why gas, and when not to
A gas heater is the fast option, and speed is the whole case for it. A large unit lifts a 20,000-gallon pool ten degrees in about five or six hours, regardless of cloud or air temperature, and it costs less to buy than a heat pump of comparable real output. Against that it is roughly two and a half times a heat pump’s running cost per delivered BTU:
| Heater | Input | Delivered per hour | Hours | Fuel cost |
|---|---|---|---|---|
| Pentair MasterTemp 400 (82%) | 400,000 | 328,000 BTU | About 5 | $47.24 |
| Raypak 336 (82%) | 336,000 | 275,520 BTU | About 6 | $47.24 |
| Hayward H-Series 150 (82% assumed) | 150,000 | 123,000 BTU | About 14 | $47.24 |
| MasterTemp 400 propane (82%) | 400,000 | 328,000 BTU | About 5 | $59.41 |
Fuel cost for the job is the same for every natural gas heater at the same efficiency — a bigger heater burns the fuel faster, not more of it. EIA residential prices for June 2026. The derivation.
The rule that falls out of that table: if you hold a temperature all season, the running-cost gap to a heat pump compounds every day and gas is usually the wrong buy. If you heat on demand — a weekend pool, a shoulder-season warm-up for visitors — you pay the premium for a handful of hours a month and the speed is worth it. The head-to-head settles that question properly.
The rating trap
The gas line decides more than the heater does
A heater has to be fed by a gas line sized for its input rating, and a line that serves a house was not specified with a 400,000 BTU appliance in mind. Upsizing a gas run is frequently the largest item on the quote, and it is the item people discover after buying the heater.
That is the real argument for the 150,000 BTU class, and why the Hayward H-Series is on this list despite being the slowest pick. It asks less than half as much of the supply. On a modest pool, seven extra hours of heat-up is usually much cheaper than a new gas line, and get the line priced before you commit to any of these.
What each maker will actually say about efficiency
| Heater | Efficiency stated | Exchanger | Low NOx |
|---|---|---|---|
| Raypak 336 Digital | 82% in the listings | Copper fin tube, polymer headers | Yes |
| Pentair MasterTemp 400 | Described as best in class, no percentage | Not stated in the listings we read | Yes |
| Hayward Universal H-Series 150 | None for the current W3HS150FDN | Cupro nickel, standard | Yes |
Where a maker gives no percentage we run the unit at 82%. An 84% figure circulated in retail copy for Hayward's older H150FDN, but neither the current W3HS150FDN listing nor Leslie's page for it states one, so we no longer attach it.
None of this is a knock on any of the three. It is the state of publication in this category, and the reason our running-cost figures use one assumption for all of them rather than pretending to a precision the makers do not offer.
Natural gas or propane
If the answer is propane and there is no prospect of a gas line, the decision is a different one from the rest of this page — the fuel costs about a fifth more per delivered BTU, the tank is part of the purchase, and the burn rate per hour is the number that matters. Our propane pool heater guide ranks the LP models and does that arithmetic.
The same heater with a different burner, and one number changes: propane costs about $35.66 per million BTU delivered against about $28.36 for natural gas, at US average residential prices — a quarter again more. It also means a tank and a delivery contract. If you have a gas line, use it. If you do not, propane is the fast option and the heat-pump comparison gets harder for it to win.
Sizing a gas heater
| 20,000 gal x 8.33 x 10°F | = 1,666,000 BTU |
| Wanted in 6 hours | = 277,667 BTU/hr delivered |
| Divide by 82% efficiency | = 338,618 BTU/hr input |
| So: a 336,000 to 400,000 BTU/hr heater |
Oversizing a gas heater wastes purchase price and gas-line capacity, not fuel: the job takes the same BTU whichever heater burns it. Undersizing means never reaching the set point on a cold day.
Buy the cover first
On gas the cover argument is at its strongest, because every hour the burner runs is fuel you paid for. About 70% of a pool’s heat loss is evaporation, and a cover on the water overnight means the heater is replacing far less of it the next day. The cover picks, and the ranked comparison across every heater type if you are not yet sure gas is the answer at all.
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.
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 October 17, 2026.
Pentair MasterTemp 400 Natural Gas Pool Heater
The third name in every gas-heater comparison, and the one the listings describe as the quiet one. It is a 400,000 BTU/hr input heater, low-NOx certified, which puts it in the same class as the biggest Raypak — and therefore in the same speed bracket: hours rather than a day. Pentair does not state a thermal efficiency percentage in the listings we read, so we run it at the 82% we assume for gas generally.
Best for A full-size pool heated on demand, when you want the largest gas class
| Rated input | 400,000 BTU/hrGas convention: fuel burned per hour, not heat delivered. Delivered heat is this figure times the thermal efficiency. | Retail listing |
|---|---|---|
| Emissions | Low NOx certified | Retail listing |
| Thermal efficiency | Not stated as a percentage in the listings we readThe listings say best-in-class efficiency without a number. We run it at 82%, the assumption we use for every gas heater on the site, and would revise it if Pentair published a figure we could cite. | Retail listing |
| Cost per million BTU delivered | About $28.36 at 82% efficiencyUS average residential natural gas at $24.09/Mcf (EIA, June 2026). | Our arithmetic |
- Largest common residential gas class, so the fastest heat-up on this site
- Low NOx certified, so it is permitted in the air districts that require it
- Described across listings as noticeably quieter than the older gas designs
- Roughly two and a half times a heat pump's cost per delivered BTU
- 400,000 BTU/hr demands a gas supply most houses were not piped for
- No thermal efficiency percentage in the listings, so the efficiency claim is unverifiable
- Real delivered efficiency in service
- Heat exchanger life against your water chemistry
- Whether your gas meter and line 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 October 17, 2026.
Hayward Universal H-Series 150,000 BTU Natural Gas Heater
The gas heater for a pool that does not need 336,000 BTU an hour thrown at it. At 150,000 BTU/hr of input it is under half the fire of a full-size unit, which costs you speed and buys you something people discover too late: a much smaller gas supply to feed. On a modest inground pool or a big above-ground one, that is often the difference between using the gas line you already have and paying to upsize it.
Best for A modest pool where the gas supply, not the heater, is the real constraint
| Rated input | 150,000 BTU/hrHayward publishes this as a BTU/hr rating, in the gas convention: fuel burned per hour, not heat delivered into the water. | Manufacturer |
|---|---|---|
| Current part number | W3HS150FDN, which Hayward's listing states replaces the H150FDNSame heater class, current SKU, with the OmniX control. The older H150FDN part number still appears in older reviews and stock. | Retail listing |
| Heat exchanger | Standard cupro nickelCupro nickel is the corrosion-resistant option on most gas heaters and a paid upgrade on some. Hayward lists it as standard on this one. | Manufacturer |
| Thermal efficiency | Not stated for the current W3HS150FDNConfirmed on Hayward's own product page, read 17 October 2026: there is no thermal efficiency percentage anywhere on it. The only efficiency-shaped figure is a claim of savings of 'up to 18%', which refers to reduced PUMP run time rather than to combustion. An 84% figure circulated in retail copy for the older H150FDN; it does not appear for the current part, so we no longer attach it and run this heater at the 82% we assume for gas generally. | Manufacturer |
| Water flow window | Min 20, max 125Quoted exactly as Hayward publishes it — the specification table does not state the unit, though gallons per minute is the convention and the figures only make sense that way. Hayward advises keeping flow above the minimum with allowance for a dirty filter, to protect the exchanger. | Manufacturer |
| Connections | 2 in x 2-1/2 in CPVC unions | Manufacturer |
| Electrical | 120/240V, 60 Hz single phase, 5.5 circuit amps, 15 A max breakerHayward's table also carries a 'Power: 44 kW' row, which cannot describe this appliance: 5.5 A at 240 V is about 1.3 kW, and 44 kW would not sit behind a 15-amp breaker. We read it as a data-entry artifact and flag it rather than repeat it. | Manufacturer |
| Warranty | 1 year parts, no laborAt the shorter end of this category. For contrast, FibroPool states a Limited Lifetime warranty and TURBRO gives 2 years on the machine with 5 on the compressor, both on much cheaper units. | Manufacturer |
| Cost per million BTU delivered | About $28.36 at our 82% assumptionUS average residential natural gas at $24.09/Mcf (EIA, June 2026) divided by 82%, the same assumption we apply to every gas heater without a published efficiency figure. | Our arithmetic |
- Roughly half the gas demand of a full-size heater, which is often what decides the install
- Cupro nickel heat exchanger listed as standard rather than as an upgrade
- Low NOx certified, so it is permitted in the air districts that require it
- Slow for a gas heater: about 14 hours to lift 20,000 gallons ten degrees
- Still gas, so still roughly two and a half times a heat pump's cost per delivered BTU
- Hayward publishes no thermal efficiency figure for it on its own product page
- The thermal efficiency it actually delivers — no figure is published for the current part
- How the cupro nickel exchanger holds up against your water chemistry
- Whether your gas meter and line 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 October 17, 2026.
Pentair MasterTemp 400 Propane Pool Heater
The same MasterTemp 400 with a propane burner, for the large share of pools with no natural gas line. Everything about the machine is the same and one number is not: propane costs about a quarter again more per delivered BTU at US average prices, which makes the heat pump comparison harder for it to win and the speed argument the whole case.
Best for A full-size pool heated on demand, where there is no natural gas
| Rated input | 400,000 BTU/hrInput, not output. | Retail listing |
|---|---|---|
| Fuel | Liquid propane | Retail listing |
| Emissions | Low NOx certified | Retail listing |
| Cost per million BTU delivered | About $35.66 at 82% efficiencyUS average residential propane at $2.674 per gallon (EIA, week ending 30 March 2026). About a quarter more than natural gas for identical heat. | Our arithmetic |
- The largest gas class where there is no gas line
- Same speed as the natural gas version — hours, not a day
- Low NOx certified
- About a quarter more per delivered BTU than natural gas, and over three times a heat pump
- Needs a propane tank and delivery contract, which is a running commitment
- No thermal efficiency percentage in the listings
- Real delivered efficiency in service
- Heat exchanger life against your water chemistry
- Tank sizing for your usage pattern
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 October 17, 2026.
Sun2Solar 1600 Series Ultimate Blue Solar Cover
The cover to buy if you intend to keep using it in five years. 16 mil is the thickest tier the category sells, and thickness on a solar cover buys durability rather than heat — Bob Vila measured every cover in its hands-on group at the same 4 to 5 degrees, from 12-mil clear to 16-mil blue. Pay the extra for the one that survives being dragged over the coping twice a day, not for a temperature difference that did not show up in the only published one-hour test in this category.
Best for An inground pool you cover most nights, every season
| Price shown for | 24 ft roundThis product is sold in several sizes on one listing. The live price and photograph on this page are the ones Amazon returns for this variant; other sizes are priced separately. | Retail listing |
|---|---|---|
| Thickness | 16 milThe manufacturer publishes no retrievable specification sheet; figure is as listed at retail. | Retail listing |
| Color | Blue | Retail listing |
| Stated lifespan | 5 to 10 years for the 16-mil tierSwim University's published figure for 16-mil covers generally, not a Sun2Solar warranty statement. | Retail listing |
| Bubble side | Bubbles face the waterCategory-wide instruction, not brand-specific. The bubbles are the insulating layer and they have to touch 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
Their figure was the same for every cover they put on the water. Read our reconciliation of what a one-hour reading actually measures before you plan around this number.
- Thickest tier sold, which is where the durability difference actually is
- Blue absorbs more of the incoming energy at the surface than clear does
- Cuts oversize to your pool shape with household scissors
- Heavy and awkward at 16 mil — a large inground cover is genuinely a two-person job without a reel
- Costs meaningfully more than the 12-mil version for no measured heating advantage
- Whether the seams hold up over five seasons of daily handling
- How the bubble layer survives repeated dragging over rough coping
- Whether the stated lifespan tier holds for this specific product line
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 October 17, 2026.
Questions people actually ask
What is the best gas pool heater?
How many BTU gas heater do I need?
Is a propane pool heater more expensive to run than natural gas?
Can my existing gas line run a pool heater?
Gas heater or heat pump?
- 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.
Read next
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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.
Solar panels vs a gas pool heater
Zero dollars per million BTU against about twenty-eight, and roughly a day of sunshine against about six hours. Which trade suits your pool, and the case for owning both.
Hayward Universal H-Series review
Hayward's 150,000 BTU gas heater on the record: cupro nickel as standard, a published flow window, one year of parts cover, a power rating that cannot be right, and no thermal efficiency figure anywhere.