How Does an Above Ground Pool Heater Work?

Warm Air

The majority of above ground pool heaters are heat pump heaters. These consist of a fan, an evaporator coil, an electrical pump, a compressor and a heat exchange condenser. There are no electrical heating elements. Instead, the heaters rely on the sun to warm the air at least slightly. The fan blows the warm air through the evaporator coil, which contains liquid refrigerant. The role of the liquid refrigerant is to collect the heat from the air. As the fan blows the sun-warmed air through the coil, the heat is absorbed by the liquid refrigerant, which turns into a gas.

Pumping Gas

Now the pump kicks in, moving the gas into the compressor. The compressor's job is to intensify the heat in the gas. The gas becomes very hot, and travels to the heat exchanger condenser. At the same time, the pump is pumping cool pool water through the heat exchanger. The cool water and hot gas meet, and the hot gas warms the cool water. The water becomes warm, and the gas cools down. The warm water is then pumped out into the pool.

A Water Cycle

As the gas cools down, it becomes a refrigerant liquid again. The liquid is pumped back into the evaporator air coil. The whole process is a circular one, and it is repeated continuously until the water in the entire pool is warmed. If it is a particularly hot day, the water can get too warm. In this case, the pool heater's pump can be turned off. Oftentimes, during the hot summer months, the above ground pool heater is not turned on at all.

As the water cycles, it often passes through a filter. Some heating systems have filters as part of the unit, while others are sold separately. Large pools will have a different pump just to pump water through the filter.

Resources

• More about above ground swimming pool heaters.