Old radiators won't turn off even with thermostatic valve at 0

FataVerde

I have two older radiators with Bulldog thermostatic valves. They were in the house when we moved here so no idea how old they are. First, the bedroom radiator would not turn off when I set the thermostatic valve at 0. I watched a few online videos on removing the valve head and I unscrewed it thinking it might be broken. The valve body goes up and down when I move the thermostat from 0 to 5, which seems to be ok. Then I took another bulldog valve head off from the hallway radiator and tried it on the bedroom one, but that did not work either. I screwed it back on the hallway radiator, which we keep turned off, but now this one won't turn off either. I typically don't leave these radiators on during the day as we don't use those spaces so I'd really like to be able to turn them off. 

We have a bathroom radiator with a Bulldog valve and that works to turn it on or off, but fails to turn off either the bedroom or the hallway radiators. The valve pin on both these radiators are moving but it does not fell like they go down all the way. I pushed them with pliers and tried some oil on them, but it's still not working.

Am I right in concluding that the problem is with the pin and the valve body rather than the head? Do you have any other tips for unsticking the pin? or am I at the stage at which I should really call a plumber to replace the valves? Is there any way to completely close a radiator (for the hallway one, which we are not using? 

Thanks!

molerat

Gently tapping with a small hammer usually does the trick.  If you want to turn the other rad off completely you can close the valve on the other side but take a not of how many turns it takes as that is used to balance the radiators so would need putting back in the same place.

theoretica

If the pin won't budge and tapping with a hammer doesn't work, for the one you want off look at the other end of the radiator - there may be a valve there you can close - probably with an adjustable spanner. 

FataVerde

Thanks, I think I managed to lock the hallway radiator with 8 turns. I'll have another try with the hammer at the bedroom rad.

nofoollikeold

I assume you have closed the valve at the other end of the radiator - the lock-shield valve.  When doing so you should count the number of 1/8 turns required to close it, so that it can be re-opened to the same point and preserve the balance of the system.  

ThisIsWeird

Hi FV.
If your lockshield was 8 turns open, I think we can conclude your system wasn't balanced, and that the rad was getting an unrestricted flow. As Molerat says, you should, as a rule, count how far open these l/s valves are so you can return them to their original position after fiddling, but I suspect it's moot in this case.
Could we have a pic of the valve under the TRV head, please?
The pin should be free-moving, tho' requires a firm push. It should move, ooh, around 6-8mm, smoothly, and bottom-out firmly with a gentle thunk. And then pop back up instantly when released. Does it?
You can also check it by opening the l/s a couple of turns, and running your CH. You'll usually hear the hiss of water passing through. Press the pin down, and for most of the travel there will be no real change in noise. Then the hiss usually increases slightly in pitch and can even become louder as the flow begins to be restricted. Finally the hiss should fall off to zero as you press the pin fully home. Does it?
The TRV head seems to be working from what you say. Before refitting, is it smooth to turn through 5 to 0? Now fit it, set to 5 as it's easier, and turn it off. At what point does it become noticeably more stuff? And how does it feel as you close it right down?
You'd expect it to feel loose, easy to turn, down to around 3 if the room is at around 20oC, then quickly become more firm as it actually begins to shut off the valve (press down the pin), and then possibly a slightly increasing level of firmness, but still smooth. Does it, instead, become noticeably more stuff or resistant beyond,say, 2 or as you pass 1? 

vacheron

if the pin is stuck down, (which is unlikely if the heat is always on), you can also grip the pin with a par of pliers and pull it up and down a few times. This way you can feel it top and bottom out cleanly when it is fully free.