The frost symbol is exactly that. If set to frost the thermostatic head will not allow the valve to open unless the temperature drops below 7 Degrees C. The frost setting should never be used when removing a radiator. All TRV4 valves come with a decorator cap. The TRV head should be removed from the valve body and the cap installed in its place and fully tightened thus giving a positive shut off for the valve.Failure todo this may lead to the valve opening and flooding the room.
Answered by: Martin, Technical Support
Date published: 2018-03-06