Pool and spa heater reference guide

If your replacement heater will be used to heat your pool, then replace it with a heater of the same b.t.u. capacity as the current unit.

Do you want to heat just your spa because it is cost prohibitive to heat the pool? If this is the case then a heater of just 250,000 b.t.u. or less is plenty to quickly heat most residential spas.

100,000 btu heater - up to a 300 sq. ft. pool.

150,000 btu heater - up to a 450 sq. ft. pool.

250,000 btu heater - up to a 700 sq. ft. pool.

300,000 btu heater - up to a 900 sq. ft. pool.

350,000 btu heater - up to a 1050 sq. ft. pool.

400,000 btu heater - up to a 1200 sq. ft. pool.

Figures based on a 30 degree F. temperature rise, 3 1/2 MPH average wind velocity and elevation up to 2000 feet above sea level.