Pool Heat Pump BTU Sizer

Size a pool heat pump without guesswork. Enter the pool's surface area and the temperature rise you want, then adjust for wind exposure and cover usage to see the BTU/h capacity, tonnage, and kilowatt output required.

Surface area exposed to air; length × width for rectangular pools or the average for irregular shapes.
Degrees Fahrenheit you want to raise the pool above ambient or current temperature.
Defaults to 10 BTU/ft²·°F for average wind exposure. Increase for windy or shaded pools.
Defaults to 1.0. Raise above 1.0 for exposed pools, lower toward 0.8 if sheltered.
Defaults to 0%. Enter the expected percent heat loss reduction from using a cover when the pump runs.

Sizing assumes steady-state conditions. Consult manufacturer manuals for minimum flow rates, ambient temperature limits, and electrical requirements before purchasing a heat pump.

Examples

  • Example 1 — 600 ft² pool, 15 °F rise, defaults for loss factor and exposure ⇒ Required heat pump capacity: 90,000 BTU/h | Approximate tonnage: 7.50 tons | Thermal power: 26.38 kW
  • Example 2 — 850 ft² pool, 12 °F rise, 12 BTU/ft²·°F loss factor, 1.2 wind multiplier, 30% cover reduction ⇒ Required heat pump capacity: 85,680 BTU/h | Approximate tonnage: 7.14 tons | Thermal power: 25.10 kW

FAQ

How do I estimate the heat loss factor?

Start with 10 BTU/ft²·°F for mild climates, increase toward 12–15 for windy coastal sites, and drop toward 8 for sheltered pools or when you run the heater only in warm seasons.

Does water depth matter?

Depth influences total water volume, but the dominant load for heat pumps is surface heat loss. Use surface area for sizing, then verify the heater's heating rate meets your recovery-time expectations.

Can I size for spa mode with this calculator?

Yes. Enter the spa surface area and higher temperature rise (often 30–40 °F) to gauge the dedicated BTU/h needed for rapid spa heating.

What if I use gas or electric resistance heating instead?

The BTU/h requirement is the same; compare the output with your heater's rating to check whether it can maintain the desired temperature under similar conditions.

Additional Information

  • Heat loss factor captures convection and evaporation; 8–12 BTU/ft²·°F is typical for residential pools.
  • Wind multiplier adjusts the load for exposed decks, rooftops, or screened enclosures.
  • Covers reduce evaporation dramatically. Enter the estimated percentage savings to downsize the required capacity.
  • Tonnage divides BTU/h by 12,000, while kW converts thermal output to SI units for comparing manufacturer specs.

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