Energy Guide

higher average wind speeds at the pool surface, lower humidity, and cool nights will require a
larger heater.
Heat pump pool heaters are rated by Btu output and horsepower (hp). Standard sizes include 3.5
hp/75,000 Btu, 5 hp/100,000 Btu, and 6 hp/125,000 Btu.
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.
Determining Heat Pump Swimming Pool Heater Efficiency
The energy efficiency of heat pump swimming pool heaters is measured by coefficient of
performance (COP). The higher the COP number, the more efficient. However, there is no
standard test for measuring the COP. Therefore, you really can't compare the COPs of different
models unless you know that the manufacturers used the same test for each model. For example,
the same heat pump will operate at a higher COP when the outside air temperature is higher.
Typically, manufacturers measure the COP by testing a heat pump pool heater with an outdoor
temperature of 80ºF and pool temperature of 80ºF. COPs usually range from 3.0 to 7.0, which
converts to an efficiency of 300%–700%. This means that for every unit of electricity it takes to
runs the compressor, you get 3–7 units of heat out of the heat pump.
Estimating Heat Pump Swimming Pool Heater Costs and Savings
For an outdoor swimming pool, use the following tables to help estimate your annual heat pump
pool heater costs and savings compared to using an electric resistance or a gas pool heater.
Table 1 estimates annual swimming heat pump pool heating costs by location, by water
temperature, and with or without using a pool cover.
Table 1. Costs by Location of Heating Outdoor Pools with a Heat
Pump*
Location
Season
Temperature
78°
80°
82°
Miami
1/1–
12/31
$1100
$1460
$1845
w/ cover
1/1–
12/31
$215
$300
$410
Phoenix
3/1–
10/31
$680
$875
$1090
w/ cover
3/1–
10/31
$45
$85
$125
Dallas
4/1–
10/31
$760
$970
$1240
w/ cover
4/1–
10/31
$90
$140
$205
Atlanta
4/1–
10/31
$840
$1110
$1425
w/ cover
4/1–
10/31
$155
$205
$290
Los Angeles
5/1–
10/31
$950
$1210
$1485
w/ cover
5/1–
$85
$155
$240