To calculate an approximate heater size for an outdoor swimming pool, follow these steps:
- Determine your desired swimming pool temperature.
- Determine the average temperature for the coldest month of pool use.
- Subtract the average temperature for the coldest month from the desired pool temperature. This will give
you the temperature rise needed.
- Calculate the pool surface area in square feet.
- Use the following formula to determine the Btu/hour output requirement of the heater:
Pool Area x Temperature Rise x 12
This formula is based on 1º to 1-1/4ºF temperature rise per hour and a 3-1/2 mile per hour average wind at the
pool surface. For a 1-1/2ºF rise multiply by 1.5. For a 2ºF rise multiply by 2.0.