1 cold radiator upstairs - TRV

20 Nov 2005
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United Kingdom
1 of my upstairs radiators has suddenly stopped working, and now it's permenantly cold. It has a thermostatic radiator valve (Honeywell) and was working fine until Friday. Now it won't heat up regardless of the setting of the TRV.

The pipes into the TRV are also cold, as well as the outlet pipe. I have tried bleeding the air from the radiator, but there was no air in it to bleed - all that came out was clear water. I also tried turning off all the other upstairs radiators, but it made no difference.

All of the other radiators seem to be working fine.

Is it more likely to be the TRV that's failed or a blockage in the pipe (it is a hard water area). Is there any way to force a stuck TRV to open manually?

The house and entire heating system are 5 years old.
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I have exactly the same problem, my TRV is Myson. the trick is to take off the the whole plastic bit , there shold be a ring under the regulator with serrated edges, loosen this and the TRV should come off, you will then see a little pin sticking out of the bottom valve( the bit still attached to the rad), press this down a few times, to unstick it, it worked for me, the problem I have now is when I refit the TRV the radiator goes cold again.
hope this helps
Thanks for the advice. I had also managed to work out which bit comes off - it's always the problem when people just say take the top off, you don't know which bit is supposed to come off. As you say, there is a metal knurled collar beneath the plastic top that just unscrews with fingers, then the whole plastic piece comes off. The metal prong that is then exposed needs to be pulled up with pliers (and pushed up and down a few times to loosen it). It's fixed my problem, although it is still sticky, so I've had to give it the pliers treatment a few times. ;)
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The metal prong that is then exposed needs to be pulled up with pliers
No it doesn't! If you read the post on this in the sticky reference topic above you would see that you should not pull the pin out.
Not sure what you mean by "no it doesn't". Or how to find the "sticky" forum.

Pulling the pin back up has certainly worked for me. Changing the setting of the valve to cold has the effect of pushing down on the pin. But it is not attached to it, so it can't pull it back up again when you set the valve to hot. Presumably there is some sort of spring that normlly pushes up the pin when you release it by turning the valve setting to hot.

In my case it's clearly been stuck in the down (shut position), and presumably the spring is not quite strong enough to overcome the friction of a stuck pin - particularly when it hasn't been used for a while. The only way to get it to come back up when stuck is to pull it up manually e.g. with pliers. So what's wrong with that?
Hi - we have just moved to this house and all the radiators work fine except two upstairs in adjoining rooms that seem to be at the end of the loop. The pipes either side of both are cold and there is no air in the two radiators. They are fitted with thermostats and the inlet valves are open fully. Anyone have any ideas please? If it is an airlock in the pipes, what do I look for to draw off water? Many thanks - I am not a good DIYer! :cry:
I have found this sight on searching for a answer to how to release my thermostat valve which was stuck on cold. I have removed the plastic cover and tapped the valve a few times and it released and the radiator is now hot, I am a 64 year old widow so have to do this type of thing myself, but with the help of the original post I did do it myself :D

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