Can't use your pool for several months of the year? Then maybe you should consider heating it. There are several types of heating equipment in use today.

Heat Pumps: Heat pumps have become one of the top choices for heating a pool in warmer climates. A heat pump is like a central air conditioner unit except that it pumps the heat from the air to the pool. A heat pump has a higher intitial cost than a gas heater, but the cost of electricity is much lower. A heat pump converts about 1 unit of electrical energy into about 5 units of heat compared to an electrical resistance heater. This is known as the Coefficient of Performance (COP).

The evaporator is charged with R22 refrigerant. The boiling point of R22 is minus 41°. When the fan and compressor turn on, it draws the warm air through the evaporator which contains the cold gas. The cold gas picks up the heat from the warm air. The gas flows into the compressor where it's compressed to a much higher temperature. It then enters the heat exchanger where the pool water enters and extracts the heat, and the hot gas is condensed back into a liquid refrigerant. The liquid refrigerant changes to a cold gas when it passes through the expansion valve and enters the evaporator. The cycle starts again.

Heat pumps produce enough heat to keep a pool at the specified temperature, but are not suited for rapid heat up on an occasional basis. They have controls that turn them off when the air temperature is below 45°F.

Gas heaters: Gas heaters can run on either propane or natural gas. They are less expensive than a heat pump, but the cost of the fuel is higher than the electricity for a heat pump, especially for propane. Gas heaters can have a much higher heat output for rapid heating on an occassional basis. Heaters with electronic controls cost a little more and require electrical hookup, but do not waste fuel for a continuously lit pilot.

Oil fired heaters are available, but not widely used in South Florida anymore. They run on diesel or home heating fuel. Oil fired heaters are used on the mobile pool heating rig shown below.

Solar: Solar heat does not require any fossil fuel to produce the heat. After the initial cost of installation, there are no fuel costs. Solar works well when there is plenty of sunshine and can be located on a southern or western exposure (northern hemisphere). It does not work when it is cloudy or on cold windy days. It is important to have adequate sized solar collectors; a minimum of 100% of the surface area of the pool and more for a screened pool or locations that are shaded part of the day.

Electrical resistance heaters are used in portable and smaller spas but not widely used in pools. They are much smaller in size and cost less than other types of heaters.

Mobile Pool Heating is an alternative if you do not have a heater. A self contained truck with with 6 oil fired heaters can put out 2 million BTU's of heat per hour, enough to heat a typical residential pool 11°F per hour. Hoses are run to the pool and the water is pumped through the heaters and returned to the pool. Consider this method if you are having a party or out of town guests. It has also been popular with the film industry because they can select a location with a pool because of its setting and not whether the pool is heated.

A solar blanket can add 5°F to a pool during the winter months and will reduce the costs of heating a pool. Most of the heat loss in a pool takes place at the surface of the water. Higher wind speeds increase the heat loss. Heating a pool without a blanket is like trying to heat or air condition a house with the windows open. A reel makes it much easier to remove and put the blanket back on.