Radiator has me boiling...

digannio

Many thanks for all the help. Got the cap off and the pin was indeed jammed solid but got some movement out of it after several goes with silicone lubricant and radiator is now obeying the 0 order to stay cold... and my face is indeed dry. Don't know what all the fuss was about . Thanks again to all from one satisfied customer.

Bendy_House

Digannio, undo only the serrated collar arrowed below. This should undo anti-clockwise as normal. First turn the TRV head to 'max' as this should release pressure from it.

The valve exposed underneath will have a metal pin sticking out. This should be pushable inwards with a firm thumb-push, should bottom-out with a nice firm 'clunk', and should spring back out instantly when released. If it does, then it's almost certainly working fine.

Inside the TRV head you'll see the part that pushes on this pin - see if that moves in and out as you turn the TRV head. If it doesn't, then almost certainly it's just the 'head' that's failed, and a new one can be screwed on.

Ganga

If in the same situation again you can always remove the plastic pull off cap on the other end of the radiator and screw down the valve to shut off the water flow completely till you can sort out the TRV.

digannio

Bendy_House said:

Digannio, undo only the serrated collar arrowed below. This should undo anti-clockwise as normal. First turn the TRV head to 'max' as this should release pressure from it.

The valve exposed underneath will have a metal pin sticking out. This should be pushable inwards with a firm thumb-push, should bottom-out with a nice firm 'clunk', and should spring back out instantly when released. If it does, then it's almost certainly working fine.

Inside the TRV head you'll see the part that pushes on this pin - see if that moves in and out as you turn the TRV head. If it doesn't, then almost certainly it's just the 'head' that's failed, and a new one can be screwed on.

Thanks for that. What it's now doing when set to 0 is allowing the radiator to heat up for a very short time when the central heating first  comes on but then turning off and going cold as intended and staying off as  I want it to be. Don't get why it comes on for a short time before turning off. The pin is still extremely difficult to move despite use of lubricant. I can live with it as it is although would be happier if it didn't come on at all when set to 0.

digannio

Ganga said:

If in the same situation again you can always remove the plastic pull off cap on the other end of the radiator and screw down the valve to shut off the water flow completely till you can sort out the TRV.

Thanks, this is what I may end up doing.

Bendy_House

digannio said:

Thanks for that. What it's now doing when set to 0 is allowing the radiator to heat up for a very short time when the central heating first  comes on but then turning off and going cold as intended and staying off as  I want it to be. Don't get why it comes on for a short time before turning off. The pin is still extremely difficult to move despite use of lubricant. I can live with it as it is although would be happier if it didn't come on at all when set to 0.

No idea why that would be. Unless it's the heat itself that persuades it to move!

I'm guessing there's a brass nut surrounding the pin? Ie, the pin effectively comes out of a brass 'nut'. If so, that nut is called a 'gland' nut, and is not done up tightly like other nuts, but just enough to squish a 'gland' - usually a rubber washer - that's underneath it.

The pin comes up through this rubber washer, sliding through a hole in t'middle. That hole needs to be tight enough to be water tight, but loose enough to allow the pin to slide unhindered. It sounds a bit tight in your case.

If you wanted to fix this, then a solution could be to slacken that nut a half turn or more, stopping if you see drips of water coming out. Then spray the pin with silicone lubricant, or smear silicone grease around its base, and push it in repeatedly, letting it pop out each time. It should start to be free-moving, at which point you redo the nut to where it was before, or just enough to stop and drips.

Leave some newspaper on the floor under it, and recheck it the following morning after the system has cooled down - that's when it might seep again! If it does, give the nut another 1/16th tighten.

digannio

Thanks, I'll give this a try tomorrow and let you know. Although I'll admit to some trepidation messing with the enemy... water!

FaceHead

Thanks for this thread.

Why silicone lubricant? Is regular WD40 ok, which I thought was for metal on metal  - perhaps this isn't metal on metal.

I too have a radiator that isn't respecting it's trv (i.e. comes.on full whack regardless of the trv setting) so will take it off later today and see if I can get it working.

In the short term I have turned the lockshield valve off as I'm not using that room ( but discovered that turning the trv to zero didn't stop the heat).

Bendy_House

FaceHead said:

Thanks for this thread.

Why silicone lubricant? Is regular WD40 ok, which I thought was for metal on metal  - perhaps this isn't metal on metal.

I too have a radiator that isn't respecting it's trv (i.e. comes.on full whack regardless of the trv setting) so will take it off later today and see if I can get it working.

In the short term I have turned the lockshield valve off as I'm not using that room ( but discovered that turning the trv to zero didn't stop the heat).

It's metal against rubber.

Is WD40 based on fish oil (did I read that somewhere?!), so I guess shouldn't harm the rubber? But when I use plastic push-fits, which employ rubber O rings for sealing, I always use silicone-based lubes - spray or grease - which is the correct thing to use.

I'd do a surf, "Is WD40 ok on rubber/neoprene?"

This way of getting lube' in there will also work better if the system is depressurised, but I thought that a task too far for the current job.

When you remove your head, FH, it should be obvious what's at fault - a stuck pin or a failed head. The latter is quite common after a decade or so.

The pin needs a firm push - it'll make your thumb smart - but should be smooth and end with a thunk. And then pop back out again.

shiraz99

Bendy_House said:

FaceHead said:

Thanks for this thread.

Why silicone lubricant? Is regular WD40 ok, which I thought was for metal on metal  - perhaps this isn't metal on metal.

I too have a radiator that isn't respecting it's trv (i.e. comes.on full whack regardless of the trv setting) so will take it off later today and see if I can get it working.

In the short term I have turned the lockshield valve off as I'm not using that room ( but discovered that turning the trv to zero didn't stop the heat).

It's metal against rubber.

Is WD40 based on fish oil (did I read that somewhere?!), so I guess shouldn't harm the rubber? But when I use plastic push-fits, which employ rubber O rings for sealing, I always use silicone-based lubes - spray or grease - which is the correct thing to use.

I'd do a surf, "Is WD40 ok on rubber/neoprene?"

This way of getting lube' in there will also work better if the system is depressurised, but I thought that a task too far for the current job.

When you remove your head, FH, it should be obvious what's at fault - a stuck pin or a failed head. The latter is quite common after a decade or so.

The pin needs a firm push - it'll make your thumb smart - but should be smooth and end with a thunk. And then pop back out again.

100%, total myth.