One radiator (on a single loop system) is completely cold this year. It use= d to be very efficient. On investigation, it seems the TVR valve has closed= - and no amount of 'fiddling' has opened it. Can I repair this? Ideally I = would like to remove the TVR completely as I have a room thermostat that wo= rks really well in my open plan house and I manually shut down radiators if= I don't want them on or areas are too hot. If it is complicated, I will ge= t the plumber in....
to be very efficient. On investigation, it seems the TVR valve has closed - and no amount of 'fiddling' has opened it. Can I repair this? Ideally I would like to remove the TVR completely as I have a room thermostat that works really well in my open plan house and I manually shut down radiators if I don't want them on or areas are too hot. If it is complicated, I will get the plumber in....
I presume you've tried bleeding it? Is it hot anywhere, e.g. at the inlet, outlet, along the top, bottom, etc?
TRV's generally don't work well on single pipe systems anyway, unless specially designed for them (and I think there is only one such).
Have you taken the head off and seen if the pin moves in and out, and is sprung out?
Probably. Having been forced closed all summer the valve washer has become stuck to the seat. Very common occurance. Take the control head off and you should see a small pin sticking up, hold this with a pair of pliers and work it up and down a few times that may release the washer from the seat.
I did look in the FAQ but didn't find anything about stuck TRV's. Did I miss it?
to be very efficient. On investigation, it seems the TVR valve has closed - and no amount of 'fiddling' has opened it. Can I repair this? Ideally I would like to remove the TVR completely as I have a room thermostat that works really well in my open plan house and I manually shut down radiators if I don't want them on or areas are too hot. If it is complicated, I will get the plumber in....
Chances are that it has been closed over the summer, and has stuck closed. In the head, there's a wax capsule which expands when it gets hot and pushes down on a pin in the wet part of the valve to shut the valve. If the pin sticks down, the valve remains shut even when it is cold and the head is set to Max.
You can easily remove the head without causing any leaks. Turn it to Max, and then unscrew the ring which holds the head onto the body. You should then see a little pin - about 2mm in diameter - sticking up. If you push this down (carefully, so as not to bend it) it should spring up again.
Chances are that it's already fully down and cant be pushed down any more. If this is the case, gently tap the side of the valve with a spanner. This usually frees the pin. Or grab the pin with tweezers and pull it up (again taking care not to bend it). If you work it up and down a few times, it should then start behaving normally. You can then replace the head.
If you prefer it not to behave as a TRV, you can simply leave the head off. But you won't then be able to turn that radiator off. However, you should have been provided with a decorator's cap - a plastic cap which screws on in place of the head - for use when removing the radiator for decorating, to make sure that the valve doesn't open however cold it gets. If you fit that, you can effectively convert the TRV into a manual valve.
thanks - it is definitely the TVR as tried bleeding it, and it is hot on inlet, cold on whole of radiator. I'll check it as advised and report back - thanks guys!
I've actually used Danfoss RAS-C2s successfully on a single-pipe system (actually two parallel single-pipe loops, since the system was extended after the first part-house installation). The system does have a modern pump so has decent circulation, which probably helps.
cold on whole of radiator. I'll check it as advised and report back - thanks guys!
This is what I last posted only a month ago:
I have attacked mine several times in the following way, without draining the system, and no more than a dribble of leakage. (This was a vented system at the time. Releasing pressure on a pressurised system might be advisable.)
Having unscrewed the dome, prod the pin which protrudes from the valve a few times. Mild jams can be cleared this way.
If it is still stuck, first get some old cloths or towels to catch any spillage. Remove the circlip and lift out the plate through which the pin passes. Beneath is a rubber diaphragm, which may or may not come with it. Remove it, taking care not to tear it. Water may start to well up in the valve body. Insert a screwdriver into the body, of a suitable size so that it is a fairly tight fit. A mixture of jabs and twists with the screwdriver should result in it freeing the mechanism. You will feel the spring release, and the valve will be free to move vertically.
Now you have to get things back together. Replace the rubber diaphragm, replace the plate with pin protruding through. Now comes the hard part - get the circlip back. Some of my valves have had this done so many times that I really don't want to disturb them again.
If this still does not work, then you will have to drain down, and get right into the valve to persuade the parts to move freely.
I had all the valves replaced a few years ago, when I had a new boiler, fresh inhibitor was added, and they haven't needed any attention since.
inlet, cold on whole of radiator. I'll check it as advised and report back - thanks guys!
As others have said, depressing the "plunger" sometimes works, I've also had success tapping the valve body with a pair of pliers etc. Just when you think it's a lost cause, another tap up up it goes. A few more pushes in and out of the pin to make sure it's free and you're good to go.
One thing that bugs me with TRV's is there doesn't seem to be a standard design so tops are rarely interchangeable.
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