One cold radiator

29 May 2018
Reaction score
United Kingdom

I know this question has been asked previously, but I am stumped.

I have one cold radiator in a bungalow with an oil fired boiler. I have checked / can confirm the following:
  • All other radiators are hot from top to bottom
  • Both the inlet and lockshield valves seem to let water through; checked by turning both off and seeing that i cannot bleed the rad. With one or both valves open, I can bleed the rad.
  • If I bleed the rad with both valves open the inlet pipe gets tepid, so hot water is getting to it but obviously not much as is only replaced by as much water is blead from rad.
  • The radiator is about 6 years old, re-used when we swapped it from another room.
This radiator was added to an extension a couple of years ago and was fine until the expansion vessel was replaced in the combi boiler a couple of weeks ago after which it (the rad) is cold.

I am putting off draining the whole central heating system as we do not have a drain cock fitted, but if I need to, i will fit one.

I'd be really grateful for any suggestion as I cannot work out why it's not getting hot and I'm hoping I have missed something obvious.

Thank you,
Sponsored Links
As above really... turn off all rads - then if heat reaches the dodgy rad just turn lockshields on about 1/8th of a turn on other rads...

Google/you tube ‘balancing radiators’ - follow their guidance.
Sponsored Links
Thank you very much for your help folks, I did as you suggested and it now works perfectly. A whole load of air came out of the rad in question when I bled it.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local