The difference between a pool you use four months a year and one you use seven or eight months comes down to a heater. Cold water is the number one reason pool owners stop swimming earlier than they want to. A good pool heater fixes that completely.
But pool heaters are not a one-size-fits-all purchase. Gas heaters work differently than heat pumps, and solar systems have their own set of trade-offs. The right choice depends on your climate, pool size, how fast you want the water warm, and how much you want to spend each month keeping it that way.
We broke down the four main types of pool heaters, compared the real-world costs of running each one, and picked the best option in every category.
The Four Types of Pool Heaters
Gas Pool Heaters
Gas heaters burn natural gas or propane to heat water as it passes through the unit. They are the fastest way to heat a pool, capable of raising water temperature by several degrees per hour regardless of outside air temperature. That makes them ideal for pools that are not used daily but need to be warm quickly when you want to swim.
The downside is cost. Gas heaters are the most expensive to operate, especially with fluctuating natural gas prices. They also have a shorter lifespan than heat pumps, typically lasting 5 to 10 years with regular use.
Heat Pump Pool Heaters
Heat pumps do not generate heat. They capture it from the surrounding air and transfer it to your pool water. This makes them extremely efficient, using about one-fifth the energy of a gas heater to produce the same amount of heat. The trade-off is speed. Heat pumps raise water temperature slowly, typically 1 to 2 degrees per day.
Heat pumps work best in climates where the air temperature stays above 50 degrees Fahrenheit. Below that, they struggle to extract enough heat from the air. If you live somewhere warm and want to keep your pool at a consistent temperature all season, a heat pump is usually the most cost-effective choice.
Electric Resistance Heaters
Electric heaters pass water over a heating element, similar to a water heater in your house. They are 100 percent efficient, meaning all the electricity they consume turns into heat. But electricity is expensive, which makes these heaters costly to run for full-size pools.
Electric resistance heaters make the most sense for small pools, spas, and hot tubs where the water volume is low enough that operating costs stay reasonable. For a standard residential pool, they are usually not the best primary heating option.
Solar Pool Heaters
Solar heaters use panels or mats (usually mounted on your roof) to circulate pool water through sun-heated tubing. The sun does the work, so operating costs are essentially zero after the initial installation. A well-sized solar system can raise pool temperature by 10 to 15 degrees.
The limitation is obvious: they depend on sunshine. Cloudy days and nighttime mean no heating. Solar heaters work best as a supplement to another heating method or in consistently sunny climates. Pairing a solar heater with a solar pool cover maximizes the free heat you collect during the day.
Cost-to-Run Comparison
Here is what you can realistically expect to spend each month running different pool heater types for a standard 15,000-gallon residential pool:
| Heater Type | Upfront Cost | Monthly Operating Cost | Heat-Up Speed | Lifespan |
|---|---|---|---|---|
| Gas (Natural Gas) | $1,500 - $3,500 | $200 - $500 | Fast (1-2 hours) | 5-10 years |
| Gas (Propane) | $1,500 - $3,500 | $300 - $600 | Fast (1-2 hours) | 5-10 years |
| Heat Pump | $2,500 - $5,000 | $50 - $150 | Slow (24-72 hours) | 10-20 years |
| Electric Resistance | $1,000 - $3,000 | $300 - $600 | Moderate (8-24 hours) | 5-10 years |
| Solar | $2,000 - $7,000 | $0 - $20 | Slow (days) | 15-20 years |
Operating costs vary significantly based on your local utility rates, climate, pool size, and desired temperature. These figures assume maintaining the pool at approximately 82 degrees Fahrenheit during swim season.
The takeaway: heat pumps cost more upfront but save thousands over their lifetime compared to gas. Solar costs the least to run but requires the biggest upfront investment and the most patience.
What to Consider Before Buying
Pool size matters. A heater that works perfectly for a 10,000-gallon pool will be underpowered for a 25,000-gallon one. Check the BTU rating (for gas) or the heating capacity (for heat pumps) against your pool volume.
Your climate determines your best option. Heat pumps in Florida make perfect sense. Heat pumps in Minnesota, where air temperatures drop below 50 degrees for months, do not. Match the heater type to your local conditions.
How quickly do you need warm water? If you only swim on weekends and want the pool warm fast, gas wins. If you keep the pool at a steady temperature all season, a heat pump is more efficient.
Installation requirements. Gas heaters need a gas line. Electric heaters may require an electrical panel upgrade. Solar panels need roof space with good sun exposure. Factor in installation costs when comparing options.
Pair it with a cover. No matter which heater you choose, using a pool cover cuts your heating costs by 50 to 70 percent by preventing overnight heat loss.
How We Chose These Picks
Nobody buys five pool heaters and plumbs them in side by side, and we are not going to claim we did. These picks come from deep research. We matched each unit’s BTU output or heating capacity against the pool volumes the manufacturer says it handles, checked heat pump COP efficiency figures against the utility bills owners actually report, and dug into cold-weather complaints — a heat pump that gives up below 50 degrees matters a lot in April. We also compared warranty terms and paid attention to what pool technicians say about repair frequency and parts availability. Any efficiency claim that owner data could not support cost that heater its spot on this list.
Our Top 5 Pool Heater Picks
1. Hayward HeatPro HP50HA Heat Pump — Best Overall
The Hayward HeatPro is the heat pump most pool professionals recommend, and for good reason. It heats efficiently down to 50-degree air temperatures, runs quietly, and the titanium heat exchanger resists corrosion from pool chemicals. It handles pools up to 21,000 gallons and maintains temperature steadily once it gets the water where you want it. The digital control panel is straightforward and the unit comes with a corrosion-resistant cabinet that holds up in humid pool environments. If you want one heater that balances running costs, reliability, and performance, this is the one.
2. Hayward H-Series 200,000 BTU Gas Heater - Best for Fast Heating
When you need the pool warm now, not tomorrow, the Hayward H-Series delivers. This natural gas model puts out 200,000 BTU and Hayward sizes it for in-ground pools and spas up to 600 square feet, with other H-Series models covering smaller and larger pools. Propane versions are sold separately. The digital LED control panel has self-diagnostics, gas and electric connections can go on either side, and the low-NOx emissions are certified for air quality standards. Yes, gas costs more to run month-to-month, but if you swim sporadically and want fast results, gas is the right tool for the job.
3. Goplus Solar Pool Heater (2.5 x 20 ft) - Best Budget Solar
The Goplus solar heater is one of the cheapest ways to add solar heating to your pool. It ships as two 2.5 x 10 ft collector panels that join into one 20-foot run, and the roll-up PE panels can sit on the ground, a rack, or a roof. Your pool pump circulates water through the tubes, and the sun heats it as it flows through. There is no gas or electric hookup and nothing to pay to run it. The kit includes end caps, hose clamps, connector hoses, elbows, and adapters, so installation is genuinely DIY-friendly for above-ground and in-ground pools. A single kit is modest for a large in-ground pool, so plan on multiple panels if you have a lot of water to heat.
4. MICOE 18,000 BTU Heat Pump - Best for Above-Ground Pools
Most heaters on this list are sized for in-ground pools. The MICOE is a compact air-source heat pump built for above-ground pools up to 5,500 gallons. It runs in ambient temperatures from 32°F to 109°F and can bring water up to 104°F in good conditions. You can set the temperature and schedule from the control panel or an app, it is rated at about 50 dB(A), and it uses a titanium heat exchanger for corrosion resistance. MICOE backs it with a 2-year warranty. For a small above-ground pool where a full-size heat pump or gas heater would be overkill, this is the practical pick.
5. FAFCO Solar Bear 4 x 20 ft Heater - Best Above-Ground Solar
FAFCO is one of the biggest names in solar pool heating, and the Solar Bear is its universal kit for above-ground pools. This version is a single 4 x 20 ft collector with FAFCO’s connected tube design, and it comes with a starter kit to hook it into your existing pool pump and filter. It is a bigger collector than budget mats, so it captures more sun per panel, and you can add panels later if your pool needs more heat. Installation is manageable for confident DIYers. If you are in a sunny climate and want an above-ground heating solution with zero monthly cost, the Solar Bear delivers.
Tips for Getting the Most From Your Pool Heater
Use a pool cover religiously. The single best thing you can do to reduce heating costs is prevent heat from escaping overnight. A solar cover or thermal blanket pays for itself within weeks.
Set a consistent temperature. Letting your pool cool down and then reheating it costs more than maintaining a steady temperature. If you swim several times a week, keep the heater running at a moderate set point.
Maintain your heater. Annual professional servicing extends the life of gas heaters and heat pumps significantly. Clean filters, check connections, and descale the heat exchanger as recommended.
Right-size your heater. An undersized heater runs constantly and still struggles to warm the pool. An oversized heater costs more upfront than you need to spend. Use a BTU calculator based on your pool volume, desired temperature rise, and climate.
A warm pool changes how much you use it. Pair your heater with a solid pool maintenance schedule to keep the water clean and balanced, and you will find yourself swimming far more often than you expected. And if you want to stretch the season even further, a pool enclosure traps the heat your heater produces while keeping debris and bugs out year-round.
Whether you are gearing up for summer game nights with pool speakers and pool lights or setting up a water volleyball court, having warm water makes everything better.
Frequently Asked Questions
What is the cheapest pool heater to run?
Solar pool heaters are the cheapest to operate since they use free energy from the sun. After the initial purchase and installation, your ongoing cost is essentially zero beyond the electricity to run your existing pool pump. Heat pumps are the next most affordable option, typically costing $50 to $150 per month depending on your climate and pool size. Gas heaters are the most expensive to run, often $200 to $500 or more per month.
How long does it take a pool heater to warm the water?
It depends entirely on the type. Gas heaters are the fastest, capable of raising pool temperature by 1 to 2 degrees per hour. A heat pump raises temperature by 1 to 2 degrees per day. Solar heaters work the slowest, adding heat only during sunny hours and typically taking several days to produce a noticeable temperature change. Pool size, starting temperature, desired temperature, and ambient air temperature all affect heating time.
Can I install a pool heater myself?
Solar mat-style heaters like the Goplus panels are genuinely DIY-friendly. Heat pumps require electrical work that most homeowners can handle with basic knowledge, though many prefer to hire an electrician. Gas heaters should always be installed by a licensed professional due to the gas line connections and ventilation requirements. Improper gas heater installation can create serious safety hazards.
Is it worth heating a pool?
For most pool owners, yes. A heater extends your swim season by two to four months, which dramatically increases how much value you get from your pool. If you currently stop swimming in September and start again in June, a heater lets you swim from April through October in most climates. The cost of heating is a fraction of what the pool itself costs to maintain, and the increased usage makes the investment worthwhile.
