The FEV is a proportional controller which opens or closes the heating valve as a function of the temperature deviation.
FEV-IF: To be applied in systems with i.e. ceiling, floor or radiator heating. The temperature adjuster/sensor should be mounted on an internal wall at a height of approximately 1.5 meter in such a way that the room temperature can be measured accurately.
FEV-FF: To be applied in systems with i.e. fancoils or induction units. By placing the remote sensor in the room-air inlet of the unit a smaller response time to temperature changes can be achieved which will result in a more accurate temperature control.