Advice · 6 min read
How to size a pool heater properly
Written by Belinda
- Last updated:
The short answer
Size a heater to the heat loss in the coldest month you want to swim, at your target temperature, with your real cover habits. Then check warm-up time and electrical or gas supply.
In this guide
What goes into a sizing
- Pool length, width and average depth (volume)
- Target temperature and the months you want to swim
- Local climate: air temperature, humidity and wind
- Cover type and hours on
- Daily filtration and heater run hours
Rated output versus real output
Heat pump brochures quote output at standard test conditions, often warm air. In cooler weather, output is lower. Our catalogue shows both rated and cool-climate figures from the spreadsheet so you can compare like with like.
When a calculator should say 'ask a human'
If no catalogued model covers the requirement, or inputs fall outside sensible ranges, the honest answer is expert review rather than a confident pick. The sizing tool flags this and you can send the assessment to Belinda directly.
Keep reading
General guidance from The Pool Heating Chick. It is not a substitute for advice about your specific site.
