Discuss One Cold Radiator Downstairs in the Plumbing Forum | Plumbing Advice area at PlumbersForums.net

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Hi.

I have one radiator downstairs that will just not get hot.

If I disconnect the thermostatic valve then turn it on hot water comes through.

When I reconnect it the radiator heats up for a couple of days then stops again.

I have bleed the radiators / balanced.

Any idea?

Thanks
 
Sounds like the trv pin is sticking. New valve time, they can be re-greased, although it’s not something I’ve ever done.
 
Is it the radiator itself then? Poor circulation? Does the pipe to the radiator get hot?
 
Is it the radiator itself then? Poor circulation? Does the pipe to the radiator get hot?
Is it the radiator itself then? Poor circulation? Does the pipe to the radiator get hot?

Is it the radiator itself then? Poor circulation? Does the pipe to the radiator get hot?

Is it the radiator itself then? Poor circulation? Does the pipe to the radiator get hot?
No none of the pipes get hot until I disconnect the valve and turn it on disconnected
 
Can we just confirm what you mean by valve and disconnected?

Are you talking about removing the “valve trv head”, the bit that sets/controls the temp.

Or actually removing the “valve body” which is connected to the pipes and mechanically controls the flow of water. This would require draining the system/rad etc to change?

I ask, as there’s no way I’m draining the system and swapping over 2 trv body’s to test. If I’m draining, I’d just put new in.
 
If
Can we just confirm what you mean by valve and disconnected?

Are you talking about removing the “valve trv head”, the bit that sets/controls the temp.

Or actually removing the “valve body” which is connected to the pipes and mechanically controls the flow of water. This would require draining the system/rad etc to change?

I ask, as there’s no way I’m draining the system and swapping over 2 trv body’s to test. If I’m draining, I’d just put new in.
I disconnect the trv from the actual radiator and turn it to six it pushes out hot water. When i reconnect the radiator and refill the system that radiator heats up the first couple of times but then it doesnt.
 
If
I disconnect the trv from the actual radiator and turn it to six it pushes out hot water. When i reconnect the radiator and refill the system that radiator heats up the first couple of times but then it doesnt.
So you have checked the TRV side which, could well be working, now im surmising here that when you disconnected the TRV that the water in the water radiator is drained out as a matter of necessity since you want to mess about with it. One question i have is, when you turn the TRV on when disconnected from the raditaor, is it dribbling hot water out? Or is it coming out with a good amount of pressure? If it is dribbling out then it is the TRV, if it is coming out with good pressure then the TRV is fine.

The only 2 things that are left after that point are:

Your lockshield on the other side is maybe not open fully, possibly needs balanced, though you have said you have tried that, but if the lockshield is not working correctly then this means when you connect the radiator after disconnecting, what you will be doing is filling it with hot water through the TRV which would give the perception that it is working but if the lockshield is partially shut/not working then the water will leave the radiator very slowly or not at all ( The fact that it works the first couple of times would suggest that it is partially closed) and will result in poor circulation, meaning that the water will not circulate sufficiently and so the warm water in the radiator will eventually dissipate and go cold again.

I would be inclined to change both valves and if this doesn't do the job and you are getting sufficient pressure through the TRV and lockshield then I would suggest that the radiator needs to be replaced.
 
Is the trv pin randomly getting jammed? Have you removed the head and using pump pliers pushed/pulled the pin to free it up?
 

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