3 Things to Know About Sizing a Pool Heater

Go bigger than you think Most people undersize their pool heater and end up disappointed when the pool stays cold on a breezy day. A heater that is too small runs constantly but cannot keep up when the air temperature drops.

Use the 100,000 BTU rule In a moderate climate, plan on roughly 100,000 BTUs per 10,000 gallons of water. A 20,000-gallon pool needs a 200,000 BTU heater, and you should go up another size in colder climates.

The only downside is upfront cost A bigger heater costs more initially and may require a larger gas line, but the comfort difference is worth it. A too-small heater costs almost as much to install and still leaves you cold.