Weird stuck TRV

gabbro86

Hi all,

One of our bedrooms' radiators came (we moved in the Spring) with this TRV installed:



Whichever setting we use, from 0 to 5, the radiator seems to be stuck at full flow, making the room feel like the middle of the Sahara desert. I tried to unscrew the head and put a Tado TRV on the same body. The Tado doesn't show errors when mounted, but it still doesn't seem able to change the flow level, making it essentially useless.

The TRV seems to then be stuck, but other than replacing it fully, is there anything I could do? 

QrizB

If you push on the operating pin (the chromed bit in your first photo) can you make it move at all?

You might need to press harder than is comfortable for a finger, so eg. place a hammer on the pin then push down on that.

Rodders53

Stuck Pegler Terrier TRV... a dab of silicone oil or grease or ptfe spray around the silver pin and something like a flat spanner or hammer to press it down hard repeatedly to loosen may help (the lubricant to help with future operation).  It only moves a millimetre or two between open and shut and is very hard to move (I have the T-shirt)!  More lubricant once moving, then wipe off excess.

Don't use petroleum based lubricants as there are rubber o-ring seals involved.

Two spanners, one to hold bottom brass still and another to loosen the top may help free the 'pin', then re tighten.  A drop of water may be released via the seals.

If all that fails close down the other (balancing) valve until you can swap the TRV with a new one (needing draining down and refilling of the CH with inhibitor replaced).

Chickereeeee

Those pins, mentioned above, usually get stuck in the closed/down position, rather than up/open. But try what QrizB suggested anyway. It it doesn't move, even after a tap from a hammer, you will need a new valve. If you get get it moving, and it springs back, work it a few times and you should be good, for this winter anyway.

If you can't get the pin moving, adjust the lock shield valve at the other end to reduce the flow, and manually get the rad to a more reasonable temperature..

WIAWSNB

Hi Gabbro.

As folk have said above. 

You need to figure out whether it's a faulty - or incompatible - TRV head, or it's a stuck-in-the-open position 'pin'. 

And the way to check is as described above - press the darned thing down using either a calloused thumb, or summat like a spoon over your thumb. 

It should move down smoothly, bottom-out with a dull thunk, and spring back up when released. Does it? This would normally be accompanied by a gentle hissss when 'up', and changed and goes off when down.

Then you look inside the TRV head's bottom at the plastic centre part. Observe as you turn the control from offski to 5 - does this pin move?

bjorn_toby_wilde

If it’s the head that’s failed then a straight replacement is about a tenner (search elegance TRV head).

Worth noting that the heads aren’t necessarily interchangeable. My parents had some obsolete valves on their system. When one failed I tried Drayton, Pegler and Myson, borrowed from other rads, without success.  Had to change the whole valve in the end.

Eldi_Dos

OP;
 If you have checked that the pin is operating ok the next thing to check is the head, quite often the part that pushes the pin down is a plastic of some sort and can wear away so it no longer presses the pin down, as a stopgap measure find a washer of suitable size and place that in the head so that when adjusting down it presses down on pin.