Pool Heater Sizing and Heat-Up Time
The heater a pool needs, and how long it takes to come up to temperature.
Example
You enter
- Pool volume (gallons) 20000
- Temperature rise (°F) 10
- Heater output (Btu/h) 400000
- Efficiency (0.80 gas; COP-equiv HP) 0.8
You get
- Heat-up energy 1668000 Btu
- Hours 5.2
Details, formula, and sources
Heat-up energy Btu = gallons x 8.34 x rise, and time = energy/(output x efficiency). A 20,000 gal pool +10 F takes 5.2 h on a 400,000 Btu/h gas heater at 80%, but 11.1 h on a 150,000 Btu/h heat pump. Ignores cover/standby losses. The equipment ratings govern.
Q_btu = gallons x 8.34 x dT; delivered = output x eff; hours = Q_btu / delivered.
The sensible water-heating relation (1 Btu raises 1 lb of water 1 F), by name.
The water-heating energy relation and the 8.34 lb/gal constant are standard published values. The equipment ratings and site conditions govern.
Estimate. AHJ and licensed professional govern.
Field names used by the API: gallons, dT_F, output, eff, Q_btu, hours
- Sensible heat Btu = gallons x 8.34 x dT; 1 Btu raises 1 lb water 1 Fthermodynamics
- Heat-up time hours = energy / (output x efficiency); enter COP-equiv Btu/h for a heat pumpequipment ratings
- No standby loss ignores cover/evaporation/standby losses; real heat-up runs longerscope of this tile