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PoolGearGuide

Pool Heaters & Heat Pumps

Gas heaters and electric heat pumps that extend your swim season. We compare heating output (BTU), running cost, efficiency (COP), and how each is sized to real pools — not marketing gallons.

What to know before you buy

Gas vs. heat pump is a speed-vs-cost tradeoff

Gas heaters warm water fast and work in any weather, but burn fuel every minute they run — best for spas and on-demand heating. Air-source heat pumps cost a fraction to run once the water's warm, but heat slowly and lose output in cold air. Most season-long pool owners pick a heat pump; spa and occasional users pick gas.

Size by heat load, not just gallons

A heater's BTU rating has to overcome heat lost to air, wind, and evaporation — which depends on surface area and climate far more than gallons alone. Undersize it and you'll never reach temperature on a cool, windy day. Use a sizing calculator as a starting point, then confirm against the manufacturer's chart.

COP tells you heat-pump efficiency

For heat pumps, the Coefficient of Performance (COP) is heat produced per unit of electricity — higher is cheaper to run, and figures of 5–6 are common. COP is measured under specific conditions, so treat published numbers as a best case that drops as the air gets colder.

A solar cover is the cheapest 'heater' you'll buy

Most of a pool’s heat escapes overnight through evaporation. A solar cover holds that heat, so whichever heater you buy works less and costs less to run. Budget for one alongside the heater — it changes the math.

Frequently asked questions

Which is cheaper to run, gas or a heat pump?

A heat pump, usually by a wide margin, because it moves heat from the air instead of burning fuel. The tradeoffs are slower heating and reduced output in cold weather. Gas wins on speed and cold-weather reliability, not running cost.

What size heater do I need?

It depends on your pool's surface area, your climate and wind, your target temperature, and whether you use a cover — not just gallons. Start with a heater-size calculator, then verify against the manufacturer's sizing chart before buying.

Can I install a pool heater myself?

Gas heaters require a correctly sized gas line, venting, and clearances and should be professionally installed. Most 240V heat pumps need a dedicated circuit and professional placement. The exception is small 120V plug-in heat pumps, which an above-ground owner can often set up without an electrician.

Do heat pumps work in cold weather?

Their output falls as the air gets colder, so they're best for maintaining temperature through the swim season rather than heating from cold in early spring. In cold climates or for on-demand heat, gas is more dependable.