Gas vs Electric Pool Heater
Last updated 15 October 2026
A gas vs electric pool heater comparison needs three types. Electric resistance and electric heat pumps use power in different ways. Compare the useful heat delivered for the same pool task. Then compare what it costs to supply that heat.
Gas burns fuel and passes part of its heat to water. Resistance turns electrical input into heat at a stated efficiency. A heat pump moves heat from air. Its COP is useful heat output divided by electrical input. Compare useful output at the conditions you need. Check water flow and controls too. Use local tariffs to price the task. No type always costs less.
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Gas vs electric pool heater comparison
| Decision | Gas | Electric resistance | Electric heat pump |
|---|---|---|---|
| Energy purchased | Gas, with stated heat content | Electricity | Electricity |
| Useful-output conversion | Input × thermal efficiency | Input × efficiency | Electrical input × COP |
| Conditions to retain | Fuel, model and thermal rating | Model and useful-output rating | Air, water, humidity and operating mode |
| Running-cost input | Tariff per therm or documented gas-energy unit | Tariff per kWh | Tariff per kWh plus condition-specific COP |
The pool heater calculator finds the common useful load. Gas input Btu/h is not the same as useful output Btu/h. A heat-pump table may list output while a gas label lists input. Check which side of the heat balance each number describes.
Electric pool heater output for a stated task
The same water volume needs the same heat for a given rise in temperature. Required output also depends on how fast you want that rise. Add the same loss scenario when you compare types. Otherwise one option is doing more work than the other.
For an artificial useful-output target of 100,000 Btu/h, a gas unit at 0.80 efficiency needs 125,000 Btu/h input. Resistance at efficiency 1 needs about 29.31 kW input. A heat pump at COP 5 needs about 5.86 kW electrical input for that useful output. These figures are arithmetic scenarios, not current product ratings.
The Sta-Rite engineering manual, printed page 27 separates heater input and output. NIST SP811 supplies the energy-unit conversion. The equations do not choose a model or size a fuel supply.
Climate and the rating conditions
A heat-pump table's output and COP belong to its test conditions. Look for the air and water temperatures. Check humidity too. A warm-air rating does not prove that output will stay the same in cooler air. Keep the test conditions with both figures.
The Raypak residential catalogue shows condition-specific heat-pump tables. Use a current exact-model manual to establish operating limits. Do not infer them from a different model in the same brand.
Gas and resistance models also need a useful-output rating. Read their operating manual. A large input rating does not show the allowed water flow. It does not prove that controls match or that a fitting plan is safe. Those checks belong to the exact model.
Flow and control constraints
Read the heater's minimum and maximum water flow. Compare them with actual flow. The sizing target alone is not enough. A slow pump period may move water but fail the heater's minimum. A high-flow period can exceed its maximum too.
The pool pump size calculator keeps active device limits together. Use the filter tool for the exact filter rating. If a limit is unknown, whole-system fit stays unconfirmed. Complete heat maths cannot fill that gap.
Use the heater's manual and the rules for the site for any fitting work. This comparison gives no gas pipe or wiring steps. It gives no safety-control changes. Do not bypass a flow switch to make a low-flow schedule heat.
Compare your operating expense
For useful heat in Btu, gas therms equal heat ÷ 100,000 ÷ efficiency. Electricity kWh equals heat ÷ 3,412.14 ÷ efficiency or COP. Multiply by the tariff for that fuel. Keep fixed charges apart from the cost of extra energy used.
The heating-cost calculator includes editable, dated national reference rates as a starting scenario. Replace them with your current tariff. The cost guide explains heat-up versus ongoing loss replacement.
Our methodology
We used primary heat equations and unit definitions. We read the maker's rating tables and kept their conditions. We recomputed the same useful load across all three types.
No product was installed or tested for this page. We do not rank noise, reliability or purchase price from these equations.
FAQ
Does a high COP mean unlimited heat output?
No. COP is useful heat divided by electrical input at a stated condition. Capacity is a separate output limit. A good COP does not mean a unit can heat fast enough for your task. Keep both fields and their test conditions. Check the needed output before you compare input cost.
Can one type always cost less to run?
No. Cost depends on the heat load and actual efficiency or COP. It also depends on energy rates. Climate can change heat-pump output and pool losses. Compare the same task with current tariffs. A fixed monthly bill or broad percentage cannot stand in for those inputs.
Verdict on gas vs electric pool heating
For gas vs electric pool heater choices, compare useful heat first. Keep the conditions and flow limits with it. Then price the same load at documented rates. Keep buying and fitting costs apart from running costs. This type-level guide cannot approve an exact model.