Last updated: July 2026 • Reviewed by the YardFit Pools team
The best above ground pool heater for most buyers is a heat pump — it costs more upfront than a gas or electric resistance heater but runs at roughly one-fifth the operating cost. Solar is the cheapest to run long-term but only works reliably in consistently sunny climates and takes longer to raise water temperature. Gas heats fastest regardless of weather but costs the most to run month to month.
Below we break out the best pick in each heater category with real monthly running cost estimates by pool size — the number most heater guides either skip or bury in vague ranges.
Heater Type Comparison: Solar vs. Gas vs. Electric vs. Heat Pump
| Type | Upfront Cost | Monthly Running Cost* | Heat Speed | Works in Cloudy Weather? | Best For |
|---|---|---|---|---|---|
| Solar heater | $150–500 | $0– 5 (no energy cost) | Slow (days) | No — sun-dependent | Warm sunny climates, lowest long-term cost |
| Gas heater (propane/natural) | $400–1,200 | $80–300+ | Fastest (hours) | Yes | Short heating sessions, cold climates |
| Electric resistance heater | $200–600 | $100–400+ | Moderate (hours–days) | Yes | Small pools only; expensive to run at scale |
| Heat pump | $600–1,800 | $20–80 | Moderate (hours–days) | Yes (above ~45°F air temp) | Best long-term value for most climates |
*Monthly running cost estimates based on a 15ft pool (~4,440 gal), maintaining 80°F in an ambient temperature of 65°F, US average energy prices as of July 2026. Costs scale significantly with pool size — see the full cost table below.
| 💡 The heater type decision in plain terms Warm, sunny climate + want lowest lifetime cost → Solar heater. Need heat fast, heat the pool occasionally, or live in a cold/cloudy climate → Gas heater. Plan to heat the pool regularly all season and want manageable running costs → Heat pump. Small pool (under 5,000 gal) + mild climate → Electric resistance heater is acceptable. Large pool (8,000+ gal) + electric resistance heater → Running costs will be very high. Use a heat pump instead. |
Monthly Running Cost by Pool Size and Heater Type
| Pool Size | Gallons | Solar (monthly) | Gas/Propane (monthly) | Electric Resistance (monthly) | Heat Pump (monthly) |
|---|---|---|---|---|---|
| 12 ft round | ~1,718 gal | $0–2 | $30–60 | $40–80 | $8–15 |
| 15 ft round | ~4,440 gal | $0–5 | $80–150 | $100–200 | $20–40 |
| 18 ft round | ~7,646 gal | $0–10 | $140–250 | $180–350 | $35–65 |
| 21 ft round | ~10,407 gal | $0–15 | $190–320 | $250–450 | $50–85 |
| 24 ft round | ~13,593 gal | $0–20 | $250–420 | $320–580 | $65–110 |
Estimates based on US average utility rates July 2026: electricity ~$0.16/kWh, propane ~$2.40/gal, natural gas ~$1.20/therm. Solar cost assumes adequate sun hours — cloudy climates will see higher effective costs. Heat pump costs assume air temps above 50°F. Actual costs vary by region, insulation (pool cover use), and target temperature.
| 💡 Use a pool cover to cut heating costs by 50–70% A solar pool cover (bubble wrap-style cover) reduces heat loss overnight and between uses dramatically. For any heated pool, a cover is the single highest-ROI accessory you can buy — it typically pays for itself in reduced heating costs within one season. A cover also reduces chemical evaporation and debris, lowering maintenance costs alongside heating costs. |
Best Solar Pool Heater: Smartpool SolarArc / Fafco Bear Solar
Solar heaters work by circulating pool water through panels or coils exposed to sunlight, returning warmed water to the pool. There’s no energy bill — the running cost is essentially zero. The trade-off is that they only work when the sun is out, they raise pool temperature gradually over days rather than hours, and they require adequate roof or ground space for the panels.
The Smartpool SolarArc and Fafco Bear Solar are the two most reliable solar heater options for above ground pools. Both use panel-based designs that connect to your existing pool pump; no secondary pump is needed. For a 15ft pool, plan for at least 50–80 sq ft of panel area to see meaningful temperature gains in most US climates.
| Solar Heater — Key Facts for Above Ground Pools Best for: Warm, consistently sunny climates (South, Southwest US). Less effective in the Pacific Northwest or Northeast. Installation: Panels mount on roof or ground frame. Connects to existing pool pump plumbing. Panel area needed: Roughly 50% of pool surface area as a minimum. A 15ft pool (177 sq ft surface) needs ~90 sq ft of panels. Running cost: Effectively $0/month once installed. Upfront cost: $150–500 for panels; professional installation adds $200–600 if needed. Limitation: Cannot heat the pool on cloudy days or maintain temperature in cold ambient air. |
Who it’s for: Buyers in sunny climates who want to extend the swim season with zero ongoing energy cost.
Who should skip it: Buyers in cloudy or cold climates, or anyone who needs the pool heated quickly on demand.
Best Gas Pool Heater: Hayward H-Series / Pentair MasterTemp
Gas heaters heat pool water the fastest of any type — a 15ft pool can go from 65°F to 80°F in 6–8 hours with a properly sized gas heater, regardless of outside temperature or cloud cover. This makes gas the right choice for buyers who heat the pool occasionally for specific events rather than maintaining a set temperature all season.
The Hayward H150FDP and Pentair MasterTemp 125 are the two most reliable gas heaters compatible with above ground pool plumbing. Both are available in propane and natural gas versions. Key compatibility check: your pool pump must produce at least 30 PSI of flow to run most gas heaters. Many stock above ground pool pumps do not. Check your pump specs before buying a gas heater.
| Gas Heater — Key Facts for Above Ground Pools Best for: Occasional heating (parties, weekends), cold or cloudy climates, fast heat-up needs. Pump compatibility: Requires minimum 25–30 PSI pump flow. Check your pool pump before purchasing. BTU sizing: For a 15ft pool, a 100,000–150,000 BTU heater is appropriate. For an 18ft pool, 150,000–200,000 BTU. Running cost: $80–150/month for a 15ft pool running regularly (propane). Costs drop if used only occasionally. Upfront cost: $400–1,200 for the heater; professional gas line installation required for natural gas. Limitation: Highest monthly running cost of any heater type when used continuously. |
Who it’s for: Buyers who heat the pool occasionally and need fast results, or who live in cold/cloudy climates where solar and heat pumps underperform.
Who should skip it: Buyers who plan to heat the pool continuously all season — the monthly gas bill will be significant.
Best Heat Pump: Hayward HeatPro / AquaCal TropiCal
A heat pump is not a heater in the traditional sense — it doesn’t generate heat, it moves heat from the surrounding air into the pool water. This is why it’s far more efficient than an electric resistance heater: you’re paying to move heat, not create it. A good heat pump delivers 5–6 units of heat energy for every 1 unit of electrical energy consumed, compared to 1:1 for electric resistance.
The Hayward HeatPro and AquaCal TropiCal are the two most widely recommended heat pumps for above ground pools. Both are designed to work with existing above ground pool plumbing and are available in sizes appropriate for pools from 10,000 to 20,000+ gallons. One key limitation: heat pumps lose efficiency below about 45°F ambient air temperature and stop working effectively below 40°F. In climates with cold springs or falls, a heat pump extends the season but won’t heat a cold pool in near-freezing air.
| Heat Pump — Key Facts for Above Ground Pools Best for: Buyers who heat the pool regularly all season and want the lowest ongoing energy cost. Efficiency: 500–600% efficient vs. 100% for electric resistance heaters. BTU sizing: For a 15ft pool, a 50,000–70,000 BTU heat pump. For an 18ft pool, 70,000–85,000 BTU. Running cost: $20–40/month for a 15ft pool (vs. $80–150 for gas). Upfront cost: $600–1,800 — higher than gas or electric, but pays back in 1–2 seasons of use. Limitation: Loses efficiency below 45°F ambient air. Not suitable for heating in early spring or late fall in cold climates. |
Who it’s for: Buyers who plan to heat the pool consistently throughout the swim season and want the best long-term value.
Who should skip it: Buyers in cold climates who need to heat the pool in air temperatures below 45°F — a gas heater is more reliable in those conditions.
Best Electric Resistance Heater: Intex PureSpa / Hayward CSPAXI11
Electric resistance heaters are simple and cheap to buy but expensive to run at any real pool size. They work well for small pools under 3,000 gallons — a 12ft pool or an inflatable family pool — where the volume is small enough that the running cost stays manageable. For anything larger, the monthly electricity cost quickly exceeds what a heat pump would cost.
The Intex PureSpa heater (for Intex pools specifically) and the Hayward CSPAXI11 are the most compatible electric resistance options for standard above ground pool plumbing.
| Electric Resistance Heater — Key Facts for Above Ground Pools Best for: Small pools only (under ~3,000 gal / 12ft and below). Running cost: $40–80/month for a 12ft pool. Scales steeply — $180–350/month for an 18ft pool. Upfront cost: $200–600 — cheapest to buy of all heater types. Limitation: Very expensive to run for larger pools. For any pool over 12ft, a heat pump is more cost-effective within one season. |
Who it’s for: Small pool owners (12ft and under) who want the simplest, cheapest-to-buy heating option.
Who should skip it: Anyone with a pool larger than 12ft — the running costs make a heat pump the better investment almost immediately.
How to Size a Pool Heater: BTU Quick Reference
| Pool Size | Gallons | Solar Panels Needed | Gas Heater BTU | Heat Pump BTU | Electric Heater |
|---|---|---|---|---|---|
| 12 ft round | ~1,718 gal | ~90 sq ft | 75,000–100,000 BTU | 40,000–50,000 BTU | 11 kW adequate |
| 15 ft round | ~4,440 gal | ~90–140 sq ft | 100,000–150,000 BTU | 50,000–70,000 BTU | 11 kW (marginal) |
| 18 ft round | ~7,646 gal | ~140–200 sq ft | 150,000–200,000 BTU | 70,000–85,000 BTU | Not recommended |
| 21 ft round | ~10,407 gal | ~200–260 sq ft | 200,000–250,000 BTU | 85,000–100,000 BTU | Not recommended |
| 24 ft round | ~13,593 gal | ~260+ sq ft | 250,000–300,000 BTU | 100,000–120,000 BTU | Not recommended |
BTU requirements vary with ambient temperature, wind exposure, and whether a pool cover is used. These are starting-point estimates for US conditions. Always round up to the next heater size if you’re between tiers.
Frequently Asked Questions
What is the best way to heat an above ground pool?
A heat pump is the best choice for most buyers who plan to heat the pool regularly — it has the lowest monthly running cost of any powered heater type and works in all weather above 45°F. Solar is better if you’re in a consistently sunny climate and don’t need fast heat-up. Gas is the right call if you heat the pool occasionally and need it warm quickly.
How much does it cost to heat an above ground pool per month?
With a heat pump: $20–40/month for a 15ft pool. With a gas heater used regularly: $80–150/month. With a solar heater: effectively $0/month in running costs once installed. With an electric resistance heater: $100–200/month for a 15ft pool. Using a pool cover cuts all of these costs by 50–70%.
Can you use a heat pump on an above ground pool?
Yes — most heat pumps designed for above ground pools connect to the existing pool pump plumbing using standard 1.5 inch fittings. Verify that your pool pump produces adequate flow (most heat pumps require at least 20–25 GPM) before purchasing. The Hayward HeatPro and AquaCal TropiCal are the most widely compatible options.
Are solar pool heaters worth it for above ground pools?
In warm, consistently sunny climates (Florida, California, Texas, Arizona), yes — solar heaters are worth it. The upfront cost ($150–500 for panels) pays back quickly with zero monthly running costs. In cloudy or cold climates, the panels don’t generate enough consistent heat to justify the install. A heat pump is more reliable in those regions.
What size heater do I need for a 15ft above ground pool?
For a gas heater: 100,000–150,000 BTU. For a heat pump: 50,000–70,000 BTU. For solar: approximately 90–140 sq ft of panel area. The right size depends on your climate, target water temperature, and whether you use a pool cover. Always size up rather than down — an undersized heater runs constantly and still can’t maintain temperature.
Do above ground pools lose heat faster than in-ground pools?
Yes — above ground pools lose heat more quickly because the pool walls are exposed to air on all sides, not insulated by surrounding earth. This makes a pool cover especially important for above ground pools: it reduces both overnight heat loss through the water surface and heat loss through the walls. A quality solar cover typically reduces heating costs by 50–70% compared to running an uncovered above ground pool.