Unjamming TRV without draining central heating...

srichards

srichards

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I've found a TRV that appears to be jammed full on. The thingy was set at about 3 so it shouldn't have been still red hot. I turned it down to the frost setting and it still didn't get any colder. In fact it seemed to get hotter. Turning the plastic control didn't seem to make any difference as normally you can hear the water flow changing when you find where it starts to restrict it. Is there a way of unsticking it that doesn't involve needing to drain down the system at all? I've got a spare top which may fit if the insides are broken, it looks cracked, so I'm hoping I can just put another top on to it. I'd not noticed before as the stuck one is in a room I don't use much.

Also if you fit TRVs on all but one radiator I'm assuming that last radiator will automatically become the bypass radiator? There are 3 rads without TRVs, including a tiny one in a cupboard, so I was going to leave the little one as the bypass one rather than having the bathroom one used for that. I thought this way it would then hit ticking over mode faster once all the other rads started to cool off.

I've spent the day checking gas consumption and expected it to have ticked over into idle mode hours ago but it was still running at near full even after 8 hours so I started to wonder why this was.
 
If you remove the top part (the control part) you are left with a pin that sticks up in the middle - that is the part that needs to move up and down to increase and slow the flow - try swapping the TRV with another or I have seem a plumber give it a gentle tap with a hammer - but VERY gentle until you know how much force is needed to just free it off.

However, if turning the control part doesn't do anything then i would assume it is just that part that is broken, though why I don't know it would break.I am not a plumber but work in the building trade so while I do have some experience you may get better advice if there are any plumbers here.

The bathroom rad is often the bypass rad as that is normally the room where we get nekkid so would want it warm most of the time - trying the tiny rad in the cupboard sounds fine but why would you want a hot cupboard, unless you keep the children in there ?
 
No - Suz won't let me keep my children in her warm cupboard...

I have to resort to keeping them either in the bin shed or given the weather and another thread on here I have found them fairly good at preventing my windscreen getting frosted up - the wipers hold them in place along with the thread of feeding them their mothers cooking...
 
Its more likely the thermostatic controller has failed as you should have very little issues with the valve depending on quality. As above, remove he thermostatic controller and the pin in the head of the valve should move when pressed.
 
Cupboard has smallest radiator and its a cat warming cupboard :)

I did notice the collar wasn't tightned all the way clockwise so I tightened that. The trv looks like it is moving up and down more so it might have just got unscrewed so it wasn't reaching the pin. Will find out when heating goes on again. I'm assuming to remove it I undo the collar all the way anti clockwise then the plastic controller will come off.

I did whack the side of it gently with a bit of wood that was nearby so I'm hoping that has freed it off if it has got properly stuck...
 
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srichards said:
Cupboard has smallest radiator and its a cat warming cupboard :)
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Happiness is a warm pussy no doubt about that :)

It does sound as though it may have been going round and not doing anything, in that case.
Being too far way from the "centre pin"
Hopefully thats sorted, as you said you'll find out soon :)

srichards said:
I'm assuming to remove it I undo the collar all the way anti clockwise then the plastic controller will come off.
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Yep :thumbs:
 
If it had been loose it will heat up more than normal. take it off and gently pull the pin up and down to free it, also check the inside of the plastic head. when you open/close the valve it moves in and out on the inside. If it doesnt the head is buggered, just get another one.
 
Sorry I must have misread op. So it will be a replacement head. :coat:
 
It's the golden rule if you get any issues to run around every rad and bleed out any air, Works for me even if it's the car playing up :rolleyes:
 
srichards said:
Cupboard has smallest radiator and its a cat warming cupboard :)

I did notice the collar wasn't tightned all the way clockwise so I tightened that. ........

.......I did whack the side of it gently with a bit of wood that was nearby so I'm hoping that has freed it off if it has got properly stuck...
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:eek:

Never mind a plumber, the RSPCA will no doubt be calling! :ROFLMAO:
 
Radiator collar! No animals were harmed in any of the testing :D
 
It's definitely stuck. Tightened up the collar on the TRV fully clockwise. Control moves freely but it is staying on full hot. When it's cooler I'll have to take it off and hit it with a hammer/ give it some WD40 to loosen it.

I'm just wondering if I did all this last year and that's why it wasn't tightened up as I'd loosened it to get the control off, couldn't, then totally forgot I'd even started trying to fix it...
 
You usually get a white cap on the body before the thermo controller is fitted, this allows manual control of the valve but most usually get binned or lost. If you have one try that first.
 
Thanks. I'll see if there is one floating around somewhere or it'll be a trip to wickes to get one. Having a spare one would be a good idea anyway.

Taken the controller off and the pin is stuck solid. Left it soaked in WD to see whether it will loosen without it needing a good smack.
 
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Looks like the WD soaking and being whacked with a bit of wood unstuck it. It popped up while I was battering (carefully adjusting) it yesterday. Checked it today and radiator was cool and turning it up made it warmer :)

Drayton are supposedly UK manufactured so I was going to try them first. They're cheap as well which is a bonus.
 
Suz, to stop the thing (and others!) seizing again, keep adjusting them from time to time (once a month is more than enough) all the way from * to Max. That should keep the pins moving smoothly through the range.
 
Weirdly that's the only one that has ever stuck. They're all ignored for most of the year but that one was problematic before so I think it might be wise to change the whole unit.
 
Shouldn't need the whole system draining when the job's done. You can get kits that freeze the water just the far side of the job so a plug is formed preventing leaks.
 
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