Radiator problem - busted lock shield / return valve?

[gasmannew]

Hi

I am not an expert so I apologise if any of my post come across as naive.

I have a pretty new boiler and there is one radiator on the system that never warms up and it hasn't for a long time but have just ignored it. It is most likely the last radiator in on the system.

After having a look at it over the weekend I have kind of diagnosed the problem as follows.

The old towel radiator was rusted and past its best (this didn't heat up either ) so I replaced with a new towel radiator , same width etc so no need to mess about with the pipes. Eventually got it on the wall and connected the pipes and things and on initial filling (ie radiator was empty) the radiator was hot but over time it cooled even though the flow valve was fully open.

I tried the trick of turning off all the radiators in the house and only leaving that one on and it has no effect. So whilst trying to workout what was going on I opened the return side of the radiator just so a little water was coming out and the pipes on the flow side instantly started to warm up.

This has made me think that the problem is with the flow back into the system and this is stopping the radiator staying warm. (like i said i am no expert)

Also one other thing when i open the return valve with the radiator detached water flows back (at a trickle not very fast, virtually no pressure in the water ) not sure if that adds any useful info.

Any ideas on what could be going on ?

 

[terryplumb]

Two valves have to be open for radiator to work ,the lockshield valve wouldnt normally be fully open ,but it has to be open to some degree. Your other rad that never heats up ,even when all other rads are turned off ,if it has a thermostatic valve (trv) it may be (internally ) in the closed position.