Best Pool Heaters
The right pool heater depends on how fast you need heat and what you pay for energy. Gas heats fastest, heat pumps cost the least to run, and solar is nearly free but slow. Here are the picks for each and how to choose.
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Pentair MasterTemp or Hayward Universal H-Series
Who it is for: Anyone who wants heat on demand, spas, and pools used on short notice or in cold weather.
- +Heats fast regardless of air temperature, day or night.
- +Best choice for spas and quick warm-ups before a swim.
- +Works in climates where a heat pump would struggle in cool air.
Watch out: Highest running cost, since it burns natural gas or propane. You also need a gas line or propane supply sized for it.
Hayward HeatPro or Pentair UltraTemp
Who it is for: Pools used regularly through a warm season that want the cheapest heating over time.
- +Moves heat from the air instead of burning fuel, so running cost is far lower.
- +Ideal for maintaining a steady temperature all season.
- +No gas line required, just electricity.
Watch out: Slow to heat, and efficiency falls as the air gets cold, so it is poor for quick warm-ups or cold climates.
Smaller heat pump or electric heater sized for above-ground
Who it is for: Above-ground pools that want a heater matched to their smaller volume and plumbing.
- +Sized and priced for the lower flow of above-ground setups.
- +Extends the swim season for a smaller pool affordably.
- +Simpler to install than a full in-ground gas system.
Watch out: Lower output means slow heating, and small electric resistance heaters are cheap to buy but expensive to run.
What actually matters when buying
Match the type to your need. Gas for speed and cold weather, a heat pump for low running cost over a season, solar for nearly free but slow heat. Most people overheat their wallet by buying gas when a heat pump would have done the job for far less.
Size it to your pool. An undersized heater never reaches temperature on a cold day, and an oversized one wastes money. Heater output is rated in BTU per hour; size it to your pool volume and the temperature rise you want in a reasonable time. A cover roughly doubles what any heater achieves.
A cover is the cheapest upgrade. Most pool heat is lost from the surface overnight. A solar or thermal cover cuts that loss dramatically and is the single most cost-effective thing you can add to any heater. Budget for one alongside the heater.
Check the fuel and electrical supply. A gas heater needs a correctly sized gas line or propane tank; a heat pump needs a dedicated electrical circuit. Confirm your supply before buying, since upgrading either can cost as much as the heater.
How we picked
This is a research-based guide comparing heating types, output ratings, efficiency, and a broad set of owner reviews across the major heater brands. We do not take payment for placement and have not bench-tested every unit, so confirm sizing and fuel supply for your pool before buying.
Keep your water right, too
Gear handles the cleaning; chemistry is the other half. Useful next: pool heater BTU calculator, pool volume calculator, all calculators.
Frequently asked questions
Gas heater or heat pump for a pool?
Gas heats fast and works in any weather, which suits spas, cold climates, and pools used on short notice, but it costs the most to run. A heat pump costs far less to run and is best for maintaining temperature through a warm season, but it heats slowly and weakens in cold air. Pick by how you actually use the pool.
What size pool heater do I need?
Size by BTU output to your pool volume and the temperature rise you want in a reasonable time. Bigger heats faster but costs more; too small never catches up on a cold day. Work out the heat-up time for a given heater with a BTU calculator, and remember a cover roughly halves the load.
How much does it cost to heat a pool?
It depends on the heater type, your fuel cost, your climate, and whether you use a cover. Gas is the most expensive per hour, heat pumps are far cheaper to run, and a cover cuts heating cost dramatically by stopping overnight surface loss. The cover is the biggest lever on cost.
Is a heat pump worth it for a pool?
For a pool used regularly across a warm season, usually yes. The much lower running cost pays back the higher purchase price over time. It is a poor fit if you need fast heat or live somewhere with cold air, where gas wins.