I have a valve sticking on one of my radiators. It comes on when called but does not go off (at least we are warm :-) ) I have swapped the actual heat sensor part with another radiator to no effect. Is there anyway to free the valve, as I don't want to have to drain the whole system to replace it, which seems the only other option.
It is not normally the 'head' that is causing the problem. With most TRVs, when you remove the head you will see a 'pin' sticking out of the valve. It is this pin that can become sticky when not used for a period. Grip the pin with a pair of pliers and gently work it in and out a few times to free it up. Don't pull too hard or you can pull it right out of the valve. After working it like this a few times you should find that it will operate ok again.
I usually unscrew the head, turn it upside down and use it to work the pin slightly, till it frees up... THEN, I do get my tools :) if it still sticks and a can of WD40/PlusGas/silicone grease/whatever and lubricate it. It may be sticking cos it's leaking slightly.
I have just moved into a house fitted with these, Honeywell made. They all seem to work more like a setting valve rather than as a thermostat. Do I not need to drain any water, just undo the head somehow, and then find a pin under there? I haven't tried anything yet, other things need more attention!
They are TRVs (thermostatic radiator valves). Look em up on Google for all the tech data but they work like individual thermostats for the temp around each rad... when they're not sticking :) Saves having a rad on in a room which is already warm, because the room stat is located in the hallway, where it might be cooler!
deano.
No, you don't need to drain anything to get at the operating pin - although if the valves are completely knackered you will have to drain the system down to replace them of course.
There are various ways of removing TRV heads - with some you might need a hex key - with others you simply rotate the head to the 'hottest' setting and slide a collar back to release it.
Yes, I know how they are supposed to work, but they don't. They are several years old, so this discussion caught my eye as being relevant.
--=20 Davey.
Thanks for the info. These might just move higher up the list now. I'll try the easiest to get at first, of course. Thanks.
I easily removed a head, and the pin appears to be free, it is easily moved up and down, with resultant changes in waterflow. But looking at the Honeywell website, all integral heads seem to be intended to be mounted horizontally, whereas mine are all vertical. Could this be the problem? That they are not seeing room air temperature, but are affected by the heat in the pipe underneath them? If this is the case, then a one-time drain-down and overall TRV re-orientation may be in order before winter. Comments welcome (useful ones, that is).
Most TRVs can be mounted vertically or horizontally and will function perfectly correctly either way. All mine (which I fitted myself) are mounted horizontally - but I've seen many TRVs mounted vertically.
Description of Honeywell TRV:
.Reversible flow valve body. .Wax sensor provides consistent and reliable performance.
.Sensor head may be mounted vertically or horizontally by interchanging radiator tail and copper tube fittings.
Interesting, and I have found the reference you quote. So that's not it, then. I'll work my way around the house, checking all the valves in the same way. I wonder if there is a known problem with the sensor heads, or if they are not very good even when new? All of mine behave the same way, ie not very well at all. Thanks.
If it's just the one valve sticking then why not just replace that? If your system is sealed it's quick and easy to drain down. If not then you can bung the vent pipe and cold feed at the header tank to create a vacuum which will allow you (in most cases) to remove the valve concerned, without draining the system (very little water loss). Better still- new house! Then take the opportunity to drain down, flush thru, swap valve and refill adding inhibitor. Who knows when the previous owners last had it done!
Deano.
Check to see if the ones you have can be fitted to either flow or return and that they are on the flow side of the rads if not.
According to the arrows cast into the body, they are for either direction. When I was working in industry, in process plant commissioning, control valves like these were always installed on the exit end of a heat exchanger, thereby keeping the unit pressurised. Keeping the pressure in the unit behind the valve also resulted in better flow control, so your mention of fitting to the flow side is opposite to my training.
All the valves here are indeed on the return side of the radiators, where I would expect them to be.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.