Radiator - Only Lockshield Side Pipe Warm? All aspects of plumbing questions and answers, help, tips and information

[drzeuso]

So, can anyone tell me what the problem might be if I have a cold radiator, which is only heating up luke warm on the lock-shield valve side only? This also only happens when I fully cranked the central heating to 30C and the boiler is really boiling. Otherwise it stays cold. TRV side pipe and the rad itself stays cold at all times.

Tried the obvious things like, bleeding the radiator, balancing etc – but can’t seem to get this one to work.

Since that area gets warm when everythings fully turned up - could it be that not enough pressure is getting to this rad??

We have 14 rads in the house, which are mostly fine… 3 that are completely cold and the one mentioned above which looks like it’s about to work but not really.

Any help would be appreciated!

[proptech]

Hi drzeuso

There could be many reasons for this. Although it may not be the case, it sounds like the TRV is on the wrong end of the rad. Some valves are OK with this though.
So first thing to check is if the TRV is opening fully, they can get stuck when not being used in the summer months. Remove the head, and make sure the pin is free to move.
If still no joy. open the lockshield fully, and turn off other rads to force water though.

[drzeuso]

Thanks!

That one is sorted - turned out to be a stuck pin which I freed up and got hot straight away!!

There are 3 other rads in the house still that are dead cold (no warmth at all on flow/return pipes).

This has been bugging me for a couple of weeks now but then I thought... could it be possible that these 3 rads are on a different pipe all together? separate from the others - and possibly turned off? Is this normal for a 3 storey house to have separate flow/return pipes for certain parts of the house? Now that i think of it, all the ones that aren't working are vertically aligned (ie. facing the street window).

Also, went back down to the combi boiler and found out that the middle pipe is dead cold whereas the others are hot...Could this be the reason?

Attached picture of it...

Any ideas/help would be appreciated!!!

[proptech]

I would expect the pipe you've highlighted to be cold - It's the gas supply.
It's quite possible that the system could be zoned, especially as it's 3 story. If so, there should be obvious controls. Again what happens if you turn off the other radiators, just leaving the cold ones on ?