The three-mode switch for remote operation of the WHR 930/950 heat recovery unit. The switch features an integrated filter and fault indicator. If the LED on the switch is illuminated, this means there is a fault in the unit or that the filters need to be replaced. The casing is white, RAL 9001, and by default is suitable for flush installation in a socket box with 40 mm depth. A mounting box is available for surface mounting. The switch has a maximum nominal rated voltage of 660 V. The maximum nominal operating current (pure resistive load) is 20 A. The maximum permitted connection capacity for single phase 230 V is 2.2 kW.