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Heater Sizing Guide

Heat Loss Method

This guide will assist you in determining the amount of heat loss your pool heater will have to replace. The accuracy of this sizing process is entirely based on the accuracy of the information provided.

Heat Loss Method (one page)
Surface area of the water in ft².
Desired water temperature in °F.
Must be between 70 °F and 104 °F.
Average air temperature during the coldest month of operation in °F.

The calculation provided is based on the industry standard surface heat loss calculation which assumes a 3.4 mph wind for outdoor calculations. For a 5 mph wind add 25%. For a 10 mph wind double the kW required. The use of air blowers and therapy jets will double the heat loss during operation.

Temperature Rise Method

Do you want to know the kilowatt required to achieve a desired temperature rise? This method is most commonly used for spas, when a rapid change in temperature is important.

Temperature Rise Method (one page)
Volume of water in gallons.
Can be calculated by Length(ft) x Height(ft) x Depth(ft) x 7.5
Desired temperature rise in degrees Fahrenheit (°F) per hour.

Assumes spa is covered when not in use. Formula does not account for heat loss – actual heat-up times may vary.

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