Radiator has me boiling...

Belenus

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).

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.

Whenever I have had to do that I have used a piece of plastic or a coin to protect my thumb.

Bendy_House

shiraz99 said:

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.

Yup, I thought it a bit fishy.

In that case it'll likely be petroleum-based? So possibly not the best stuff to use as it could dry out the rubber?

Bendy_House

I've done a quick surf, and the first forum I found had both opinions... https://mechanics.stackexchange.com/questions/64267/is-it-okay-to-wipe-rubber-hoses-with-wd-40

So, I'll stick with sili.

FaceHead

Another TRV back working again here. Even with a newspaper to protect my thumb, I couldn't get it moving, but a tiny tap with a claw hammer got it moving.

I gave it a drop of regular WD40 too, but will get a silicone lubricant to add to the stores when I'm next out and about. 

digannio

Bendy_House said:

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.

All right, I'll admit that I've chickened out of fiddling with something that has the potential to let water seep out! I've managed to release some of the stiffness from the pin's movement by working on it. The rad still heats up for a very short time when central heating first switched on but then switches off fairly quickly and stays off. I've decided to live with that as it's not going to have any major effect on bills overall. If things change tho I've found the same TRV in Screwfix quite cheap and will just replace the head. Thanks for all the help.

BUFF

Bendy_House said:

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?"

These days WD40 is used as an overall brand & the company does various formulations incl. silicone=based e.g. https://www.wd40.com/products/silicone-lubricant/

laceythomson

Bendy_House said:

I've done a quick surf, and the first forum I found had both opinions... 

So, I'll stick with sili.

See which one got more upvotes.