One Radiator doesn’t work

Arsenal2019

It’s come to that time of year again when the radiators near turning on I’ve recently moved into a house and discovered that one of the radiators in the house doesn’t work properly. 

I have bled all the radiators in the house and filled up the boiler back to one and a half pressure and this still hasn’t done the trick.

I have then taken the TRV valve off and then suddenly the radiator gets hot. The pin doesn’t seem to be stuck and when I push it down, it comes back up quickly as the radiator gets hot and then put the TRV valve I’ll back on but then the radiator seems to go cold again as if it’s blocking something when I put the valve back on.

Does this mean that I need a new TRV evolve or is there something wrong with the pin as if when I put the valve back on it, wedges the pin down shut?

Thank you

Eldi_Dos

Could you take the head off one of the other TRV and use that to see if problem persists.Make note of where numbers are so head can be refitted in same position.

Rodders53

Make/model of TRV head?   Pic of it and the valve associated with TRV head removed?

Possible it may be the 'wrong' head for the valve?  But it's obviously closing down the pin when screwed in place, so is either 'faulty' or the wrong TRV head for the valve.

Good suggestion to try a different head on the problem rad (and see if the problem head causes the same issue on the other radiator).

MCT56

I’d just buy a new valve from Screwfix or Toolstation (or wherever is most convenient for you). TRV,s are not expensive and it will save time and effort trying to puzzle out what’s wrong with the old one. 

ThisIsWeird

Most likely it's as you say, Arsenal.

The TRV heads often fail after 10 years or so of use, and one way they do this is by its mech remaining in the 'min' position, so keeping the valve closed all the time.

Examine the head; turn it upside down and look inside its bottom. See the plastic central bit that presses on the vale's pin? Ok, keep looking as you rotate the head from min to max and back - does it move in and out in a very obvious way? 'No', it's likely kaput, so all you need is a new head.

You can usually buy the whole valve for a similar cost to just the head, so I'd do so. Keep the valve bodies safe for fitting if/when your system needs a drain down.

Arsenal2019

Rodders53 said:

Make/model of TRV head?   Pic of it and the valve associated with TRV head removed?

Possible it may be the 'wrong' head for the valve?  But it's obviously closing down the pin when screwed in place, so is either 'faulty' or the wrong TRV head for the valve.

Good suggestion to try a different head on the problem rad (and see if the problem head causes the same issue on the other radiator).

Thank you all for the helpful comments so far

i have attached photos of the current valve 

Arsenal2019

Please find attached the photos 

Albermarle

ThisIsWeird said:

Most likely it's as you say, Arsenal.

The TRV heads often fail after 10 years or so of use, and one way they do this is by its mech remaining in the 'min' position, so keeping the valve closed all the time.

Examine the head; turn it upside down and look inside its bottom. See the plastic central bit that presses on the vale's pin? Ok, keep looking as you rotate the head from min to max and back - does it move in and out in a very obvious way? 'No', it's likely kaput, so all you need is a new head.

You can usually buy the whole valve for a similar cost to just the head, so I'd do so. Keep the valve bodies safe for fitting if/when your system needs a drain down.

I have the well known Drayton type TRV4 on some radiators. I would agree they last around 10/15 years, depending on how much that radiator is on. First they get very stiff and then fall off. The plastic inside has crumbled, it is always the same issue.
On other radiators I have the same TRVs as where there when we moved in 28 years ago, and they still work fine. I can not see any brand name on them, only the statement 'Made in Germany' , which maybe tells its own story as the Drayton ones are made in the UK. 

Arsenal2019

ThisIsWeird said:

Most likely it's as you say, Arsenal.

The TRV heads often fail after 10 years or so of use, and one way they do this is by its mech remaining in the 'min' position, so keeping the valve closed all the time.

Examine the head; turn it upside down and look inside its bottom. See the plastic central bit that presses on the vale's pin? Ok, keep looking as you rotate the head from min to max and back - does it move in and out in a very obvious way? 'No', it's likely kaput, so all you need is a new head.

You can usually buy the whole valve for a similar cost to just the head, so I'd do so. Keep the valve bodies safe for fitting if/when your system needs a drain down.

Hello, thanks for your comment. I’ve taken the valve off and had a look inside. The plastic looks ok to me and so does the pin. However I know nothing about this ahahah!!!  I’ll show a photo of what it looks like below

Arsenal2019

See below w

ThisIsWeird

This wee jobbie:

It looks extended in the pic. That's the prong wot presses on the metal pin of the actual valve.

So, when you rotate the control from min to max, does that plastic central pin move in and out? Or does it remain extended as in the pic?