I have one radiator that does not work at all (although it has worked in the past). Unlike all the other radiators that come directly of the main supply and return pipe from the boiler I can see that one end of the radiator is connected to a pipe that runs directly to the bottom of the hot water tank. I cannot trace where the other pipes goes, it seems to run towards the back of the hot water tank but cannot see where it goes after this point. Because this radiator is newly installed we don't actually know which pipe is the supply and which is the return, both pipes are stone cold. Its replacing a previous one but the installer didn't make note of which end had the thermostatic valve before he removed it and redid the pipes.
My questions are:
Why has this radiator been attached directly to hot water cylinder
Will the pipe attached to the bottom of the hot water cylinder be supply or return ?
Where logically should other pipe attach.
What could stop it from working ?