Heater Sizing + Time‑to‑Heat

Designed Zion Pools

Pool & Weather

Inputs

Pool volume (gal)

Start temp (°F)

Target temp (°F)

Ambient air (°F)

Wind (mph)

Desired heat‑up time (hrs, for sizing)

Advanced: surface & cover

Avg depth (ft)

Surface area override (ft²)

Cover on?

Energy Rates

Editable

Natural gas ($/therm)

Propane ($/gal)

Electric ($/kWh)

Heater Options

Typical defaults

Gas heater input (BTU/hr) Efficiency

Propane heater input (BTU/hr) Efficiency

Heat pump rating @80°F (BTU/hr) Ambient‑based COP

Auto from air temp (≈2.5 @45°F → 6 @80°F)

Summary

Live

Heat required

0 BTU

ΔT — °F

Est. losses @ avg temp

0 BTU/hr

A — ft² (cover adj.)

Recommended size (24h)

— BTU/hr

Gas/HP equivalents

Compare Options

Cost & time

Heater	Delivered (BTU/hr)	Net (‑loss) (BTU/hr)	Hours to heat	Fuel use	Est. cost

Assumes steady conditions; real pools vary with sun, humidity, and heat loss during warm‑up. Use a cover to drastically cut losses.

Method: Required BTU = 8.34 × gallons × ΔT. Losses ≈ U·A·(T_avg−T_air) where U ≈ 7 + 1.7·wind (uncovered). Cover factors: solar≈0.3×, auto≈0.2×. Heat pump COP increases with air temp; rating derates below 80°F.