Valves With Frost Protection Feature
Valve Frost Protection Feature
Some TRV valves have a frost protection feature. This feature may mean that the valve might not turn off fully as required when installing or replacing the radiator.
If this happens, there is a decorators cap that can replace the wheel-head – this cap pushes the thermostatic pin further into the valve housing than the wheel-head, causing the valve to turn off completely; or alternatively it is possible to remove the wheel-head and insert, say, a 5p piece on the pin then replacing the wheel-head. This extra distance treated by the coin should shut off the valve.
Great care must be taken not to over-tighten either the decorators cap or the wheel-head with the 5p piece.
Illustrated below is the Bentley TRV which has its own unique decorators/isolating cap.