Can onyone help please
I am having a problem with one of my radiators not heating up as I think it should. I have balanced the system,but this rad never seems to heat up evenly. I have shut down all the other radiators. Turned on the heating and 15 min after the the radiator starts to warm up,I still have a 10 deg C difference between the top and bottom of the radiator.
I have had this rad off and flushed it out with only slightly dark water in the returns,even after hammering the rad.

My sisters old house had same problem. After trying all normal things I drained the system and found the pipes near completely blocked.

In pure desperation I got the 12v compressor to pump up car tyres and connected it to pipe. (Likely dangerous but that's what I did) After pressure and de-pressure a number of times I got some copper bits out of the pipes. Seems the pipes from new had a scale inside and this had detached and moved.

The bedroom walls were built on top of the pipes so hard to get to any pipe work. Seems radiators and pipework was installed before the dividing walls.

I tried all sorts including conduit threading tape to clear out pipes.

Hope yours turns out easier.

Thanks for the reply, I seem to have a good supply and return water from the radiator. so not too sure what the problem is. I think it might be a case of a new radiator & see if that solves the problem,as it is not heating up as it should.
Once again thank's for your input.

A radiator is just a vessel and very little can go wrong with it. It can become blocked and it can leak or be full of air, but in the main the problem you relate to is more likely to be down to lock shield valve settings.

When I have gone to people with this sort of problem it is rarely the radiator not heating up which is at fault. Normally I find the lock shield valves on the other radiators are open two wide. Or even a spring failed in a by-pass valve.

Most condensateing boilers will reduce output or shut down if hot water is returned to them. If the single radiator can't take the whole supply from boiler then the boiler will reduce output or shut down so turning off the other radiators completely can be miss leading.

I normally start by turning off radiators close to boiler and allow the feed pipes to cool. Ensuring boiler is still running I then very slowly re-open lock shield valve until I can just feel a little heat and stop. I will then repeat with radiators further away.

Only when sure there is a temp difference on each radiator input to output will I look for other faults. The by-pass valve is reasonably easy when outside the boiler but when inside boiler not so easy to check.

As an electrician I have found I get called out thinking it's an electrical problem when it's not. But once out I do want to ensure it's not a motorised valve or something before I leave. And often it's just radiators with the lock shield valve open too far.

I have balanced the system or I think I did. But will try re doing it,before I get a new radiator. Once again thanks for the info. Will let you now how I get on.