The Danfoss control valve senses the return temperature from the underfloor heating system and opens or closes according to the temperature of the water, much the same way as a thermostatic radiator valve senses air temperature changes around radiators.

This simple yet effective mechanism ensures that the underfloor heating zone maintains a constant even temperature. The sensor head of the valve is thermostatic, sensing the temperature of the water and must not be replaced with a sensor that reacts to air temperature.