Solar collectors are designed for seasonal heating of pool water only. During the winter months, the collectors are inoperable and must be drained.

Electric heaters are designed to heat water in swimming pools and whirlpool baths, the operation consists in heating the water flowing through the heater body - the temperature of the heated water is set by a control thermostat.

A heat pump is a device that extracts low-temperature energy from the surrounding air. Through compression and expansion, the energy is converted to a higher temperature. It works on a similar principle to a refrigerator or air conditioner - only in reverse. A heat exchanger is a cylindrical vessel with a system of thin tubes through which water heated by a UT boiler, heat pump or solar panels flows. Water from the pool flows around the outer perimeter of the tubes.