One rad only getting slightly warm

[Helptav]

Hi all. I wonder if you can help please. I have recently bought a 17 year old 2 bed new build. It has a combi in the kitchen which I've just had serviced all ok. I've tried the heating recently all get piping hot apart from the main one (largest In the sitting room) the valve and pipe are really hot but the rad is hardly showing any heat. I've looked at the pin on the trv and seems to move up and down. I even tried to slacken the lock shield valve plus tried bleeding it (was no air) it's like a new rad... Any ideas please ? (Could it be that last one on the run just takes a while as only tested for half hour (all the others piping hot) thanks Paul

 

[JohnD]

Turn off all the hot ones.

Yes, ALL.

Does the cool one now get hot?

Is there a room thermostat in one of the rooms?

 

[Helptav]

I'll try that next time (it's a property I'm doing up so not there) the room stat display is currently broken (plumber meant to be sorting it but brought the wrong one) the room Stat is in the hall way (next room)

 

[JohnD]

Stat is in the hall way

Quite an old installation, then.

 

[Helptav]

2008. Do you think shutting them all off will force this to get hot?

 

[denso13]

Try that first, it will help with the next step.

 

[Helptav]

Hi all. Plumber did what you advised anyway and what I had already tried messing with the trv pin does get it working. But often after it doesn't seem to work. Do you think have a new valve fitter or am I missing something. Thanks Paul

 

[JohnD]

Turn off all the hot ones.

Yes, ALL.

Does the cool one now get hot?

What happened when you did that?

 

[Helptav]

It did get hot. However I've tried it again and it didn't seem to work..mess with the pin again and it does...

 

[gas112]

How long did you leave just that one by itself on for . And have you fully opened the lockshield

 

[Helptav]

The lockshield valve fully open. Half hour.

 

[JohnD]

What do you mean "seem?"

 

[steven lee]

That pattern usually points to the TRV itself rather than balancing. With the head off, check whether the pin springs back freely every time and whether the rad then heats properly on its own. If it heats with the head off but sticks again once the head is back on, I would change the head first. If the pin is sluggish or drops even with the head off, the valve body is the likely culprit and that is the part to replace.