Heaters are able to heat water preliminarily heated by solar collector. Maximum temperature of entering water should not exceed 60°C. Water temperature can be adjusted from 30°C up to 60°C with +/– 1°C accuracy thanks to installed microprocessor controller. The set temperature can be easily read on well visible LCD display. For user’s safety the heater is equipped with pressure and thermal switch. In order to reduce possibility of damaging the heater because of air plugging, the microprocessor controller is programmed with a program discovering air-plugging in water supply system as well as equipped with independent reed relay based sensor. The POW series heaters advantage is very easy installation. Design therefore provides free space between wall and the heater what makes easier fixed and flexible power supply cables installation.