Heaters can be powered in a variety of ways. With a heat pump-driven heater, refrigerant gas is compressed, heating coils that in turn warm the water as it passes through the heat-exchange condenser. The refrigerant gas is cooled to a liquid state again and returns to the air coil to be heated again. These heaters work well as long as the temperatures stay above 45º F or so.
A gas heater is most effective for short periods of time. Natural gas or propane is burned in a combustion chamber. This requires a fuel tank, which must be refilled when empty. Gas heaters typically cost a great deal less than heat-pump filters, but they are less efficient, which may result in greater costs over time.
A solar-powered heater converts sunlight into energy. The pools pump circulates water through the heating elements, and a timer is set so that the heater operates only during daylight hours. Because it depends on sunlight to run, cloudy or stormy weather can reduce its effectiveness.
Finally, geothermal heating systems capture the natural temperatures of the earth help to power the heat pump. These are now environmentally friendly alternatives that offer cost savings.
Just like pumps and filtering systems, the size of the pool determines the type and size of a pool heater. A pool professional can help calculate these requirements.