Does anyone have experience of this make of TRV? I recently fitted a bi-directional one to one of my radiators and it seems to have no effect on the radiator at all. The room gets up to 24 degrees, and the valve is set in the mid position, but the radiator is still on. It was quite a cheap valve so I wonder if you would expect cheap TRVs to do the job you bought them for, or do you have to spend more money if you want something that actually works