A sticking valve is probably the most common thermostatic radiator valve issue. Whether open or closed, it’s going to cause real hassle in the long run. It usually happens when adjusting the valve for the first time in a long time, such as following an extended cold spell or the summer (often one and the same!).
To fix this, set your TRV to the highest setting then undo the thermostat removal nut by hand. You will uncover a piston that will usually spring up and compress down smoothly. Take some WD40 and apply a small amount until it moves smoothly once more.
A non-responsive piston means you should replace your TRV. Stay tuned until the end of this article when we present our selection of market-topping TRVs…

