Radiator not heating up on one side

[85stu]

The radiator was removed recently in order for some plasterwork to take place and is no longer functioning properly. It's a vertical radiator and the two bars closest to the trv get hot, but the rest remain cold or at best get lukewarm after several hours of running the heating. The lockshield valve is on the cold side (although it looks to me to be the same sort of valve as the trv - only with a cap rather than a knob on top). The lockshield valve is also open (I think - the pin is not depressed and is up).

I've bled the radiator loads and only water comes out. It is also relatively new so probably not sludge. Struggling for ideas now.

 

[Mottie]

Sounds like the lockshield valve is not open. Have you tried opening it some more? I don’t get what you mean about the pin?

 

[85stu]

Sounds like the lockshield valve is not open. Have you tried opening it some more? I don’t get what you mean about the pin?

The lockshield valve is a pin valve. There is nothing pushing it down, so my understanding is that it is fully open. The cap on the valve can be tightly screwed on so it may be designed to push the pin down when fully on, but I'm not convinced it has actually done that.

 

[Mottie]

Ah well, I’ve never heard of that. Got a picture of both valves?

 

[85stu]

Ah well, I’ve never heard of that. Got a picture of both valves?

Trv and lockshield with and without cap

 

[Laurieo]

Have you tried pushing the pins up and down .Sometimes they stick down if they have been off for a while .

 

[85stu]

Have you tried pushing the pins up and down .Sometimes they stick down if they have been off for a while .

Yup-the pin is definitely moving when pushed. Noticed that it sounded more like water was flowing when the pin was pushed down a bit so screwed the cap back on but doesn't seem to be making a difference to the heat.

 

[Mottie]

I’m stumped. Never seen one like that before.

 

[Nige F]

Looks like the valves are the same for thermo and lockshield.

 

[85stu]

Looks like the valves are the same for thermo and lockshield.

Yup they are. Just removed the trv and it is identical on both sides.

 

[Gasguru]

AFAIR you can preset the valve flow with a special tool from Drayton. ie. they can act as a tamper proof lockshield. Google Drayton D34 for starters..

 

[opps]

When you put the TRV back on, you need to turn it to the hottest setting before you can screw it back down. Did you do that?

 

[opps]

Looks like the valves are the same for thermo and lockshield.

Well spotted. The OP has TRVs on both sides...

 

[85stu]

AFAIR you can preset the valve flow with a special tool from Drayton. ie. they can act as a tamper proof lockshield. Google Drayton D34 for starters..

So the lockshield (or "lockshield" seeing as I don't seem to have a traditional one) is fully open already - would something like this be any use resolving the issue I'm having atm?

When you put the TRV back on, you need to turn it to the hottest setting before you can screw it back down. Did you do that?

Well, yes, otherwise this would be an easy problem to solve

 

[opps]

Well, yes, otherwise this would be an easy problem to solve

Fair enough, however was the TRV crown always on the right hand side? Those kind of rads often have baffles but that is often a flow/return issue. TRVs seem to be less concerned about the direction of flow these days.

I am not a plumber, but.. yeah, when the pin is fully up, the valve should be open. Have you run the rad with both pins fully up?

The following might be worth while watching

https://www.draytoncontrols.co.uk/news/unlocking-secrets-trv4-0#:~:text=Each%20and%20every%20Drayton%20TRV4,is%20unable%20to%20build%2Dup.

Best of luck