I went round to my friends house because he was doing a bit of tiling and he needed assistance taking a rad off. We got the rad off OK but he wants to keep it off over night. The flow side has a Myson TRV on and it is closed as far as it can go. In a central heating book I have it says that in this sort of situation the pin on the TRV should be secured down with a special manual locking nut because if there is a temp drop in the room the valve will open. Surely if the valve is closed as far as it will go then the pin should be pushed down permanently and should not open no matter what the temp? I dont know now whether to go round and fit the rad back on or if the TRV will be OK, I wouldnt like it to open during the night and totally flood the place. What do you think?