My radiator is tepid despite bleeding

John Conlin / 11 September 2018

A reader's radiator never warms up, despite having been bled.


I had most of the old radiators replaced 3 years ago and all worked well until a few months ago when one regularly remained tepid despite bleeding. A plumber examined the thermostatic valve and said all was well but the problem remains. Any suggestions?


The fact that the radiator becomes tepid suggests that the circulation is restricted in some way. Debris may be partially blocking one of the valves. Remove the ‘blind’ cover from the lockshield valve (this is the one at the opposite end to the thermovalve) and with a spanner or pliers turn the spindle counting the number of turns to open it fully. If the radiator heats up you will have cleared the obstruction so turn the spindle back the same number of turns. If no improvement take the thermo head off the other valve and repeat the process. If the problem persists have the radiator drained and power flushed assuming the plumber was right about the thermovalve.

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