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Heat Pump vs Gas Pool Heater
Quick answer: Gas pool heaters warm water fast in any weather but usually cost more per degree; electric heat pumps heat slowly and work best in air above about 50°F, yet often cost far less to run. Choose gas for occasional, on-demand heating and a heat pump for steady, season-long warmth, especially with a cover.
The core difference
A gas or propane pool heater burns fuel and passes pool water through a heat exchanger above the flame. Its output barely depends on the weather, so it can raise temperature quickly on a cool day. A pool heat pump uses a refrigeration cycle in reverse: a fan pulls outdoor air across a coil, refrigerant absorbs that warmth, a compressor concentrates it, and a second exchanger hands it to the water. Because it moves heat rather than making it, a heat pump can deliver several units of heat for each unit of electricity, but only while the air has enough warmth to give.
Speed
Gas wins on speed. A typical residential gas heater can often lift a medium pool around a degree or so per hour in calm conditions, enough to take a cold pool to swimming temperature within a day. A heat pump of typical residential size may need several days to do the same lift, which is why owners usually leave it running to hold temperature through the season. Our pool heating time calculator shows the difference for your gallons.
Running cost
Running cost depends on three things: how much heat you need, how efficiently the equipment turns energy into heat, and what you pay for that energy. Modern gas heaters convert most of the fuel energy into water heat, typically in the low 80s to mid 90s as a percentage. Heat pumps achieve a coefficient of performance (COP) that is often 4 to 6 in warm, humid air and lower as air cools. That multiplier usually makes heat pump heat cheaper per BTU, but local electricity and gas prices can narrow or widen the gap. Plug your prices into the operating cost calculator.
Climate fit
Heat pumps shine in warm and mild climates and in the middle of the season. In shoulder months, when nights fall into the 40s Fahrenheit, output and COP drop and some units stop running below a set air temperature. Gas heaters are indifferent to air temperature, which makes them a natural choice for cool-climate owners who want to stretch the season into spring and fall, or for spas that need quick heat.
Upfront and installation
Heater prices vary by size and model, and installation often decides the total. A gas heater may need a gas line run from the meter, a larger meter, venting clearances and a permit. A heat pump needs a dedicated 240 V circuit, a pad with airflow clearance and condensate drainage. Either way, installation is professional work: gas by a licensed HVAC or pool professional, electrical by a licensed electrician. See pool heater installation cost.
Lifespan and maintenance
Both types are sensitive to water chemistry. Gas units have burners, igniters and flue paths to service; heat pumps have compressors, fans and refrigerant circuits that need a licensed technician for any refrigerant work. Typical service lives overlap. Our pool heater lifespan page covers what shortens them.
Side-by-side summary
| Factor | Gas or propane | Electric heat pump |
|---|---|---|
| Heat-up speed | Fast | Slow |
| Works in cool air | Yes | Output falls; minimum temperature applies |
| Typical efficiency | Roughly 80–95% | COP roughly 4–6 in warm air |
| Running cost per BTU | Higher in many areas | Lower in many areas |
| Install needs | Gas line, venting | 240 V circuit, airflow space |
| Best for | On-demand, spas, cool shoulder months | Daily swimming, warm seasons |
Worked example
Figures below are illustrative examples (2026-10-29), not quotes or guarantees.
Assumptions: the pool needs 100,000 BTU/h of delivered heat for 120 hours a month. Gas at 84% efficiency and $1.40 per therm: 12,000,000 ÷ 0.84 ÷ 100,000 ≈ 143 therms ≈ $200. Heat pump at COP 5 and $0.14 per kWh: 12,000,000 ÷ (5 × 3,412) ≈ 703 kWh ≈ $98. At COP 3 in cooler air the heat pump figure rises to about 1,172 kWh, or roughly $164.
Combining both
Some owners use a heat pump for steady heating and keep a gas heater for quick boosts or spa use. Others pair a heat pump with solar. Combined systems need careful plumbing order and controls, which a licensed pool professional should design. Whatever you choose, a cover reduces the hours both machines run; see pool cover heat loss.
Questions to ask before deciding
- How many days a week, and which months, do you actually swim?
- Do you want to heat on short notice, or keep the pool warm all season?
- What are your local gas and electricity prices, including delivery?
- Is there a gas line nearby, or would you need propane?
- Does your electrical panel have room for a 240 V circuit?
- Will you use a cover every night?
Climate scenarios
In a hot southern climate with warm nights, a heat pump often holds a comfortable temperature for most of the year at a modest cost, and gas may sit idle. In a mid-latitude climate, a heat pump usually covers late spring through early fall well, with gas preferred for quick early-season heat-ups. In a northern climate with a short season, owners who swim mostly on warm weekends sometimes find gas simpler, while daily swimmers still favour a heat pump plus a good cover. These are patterns, not rules; run the calculators with your own temperatures.
FAQ
Will a heat pump work in Canada?
In summer, often well; in spring and fall output drops on cold nights. Check the unit's low-temperature rating.
Is propane the same as natural gas for this comparison?
The heater works the same way, but propane often costs more per BTU. See natural gas vs propane.
Can I DIY the switch from gas to a heat pump?
No. Capping gas lines and wiring a 240 V circuit are licensed trades work.
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