Replacing thermostatic valve

kelbal

Hi, I'm trying to help a friend out who has thermostatic valves in their apartment. One of the radiators won't heat up. The normal valve on the left is open, and I turn the thermostatic valve on the right, but nothing happens, no heat coming to the rad. I open the bleed valve at the top, and water does come out.
Do these thermostatic valves go faulty? Can they be easily replaced - without having to empty the radiator and drain the entire heating system? I know this procedure in my own house, but I wouldn't be sure how to tackle this in an apartment.
Here's the valve I'm talking about....


Am I looking at this wrongly? Could it be something else other than the valve? All the other rads are heating up, can't see why this one wouldn't
thanks

K.Flyer

Its quite possibly one of two things which are relatively easy to fix.
Thermostatic rad valves heads can give trouble where the device inside the valve breaks and holds the valve closed no matter which way you turn it.
Or the pin that the valve head (handle) pushes down on in has stuck in the closed position.
First remove the valve head.
With the valve in the same position as in the picture, just below the black section under the pointer there is a silver ring, turn the ring anticlockwise to remove the head. You might have to push down on the valve to help to get the ring to turn.
With the head off turn on the heating and see if the rad heats. If it does then its most likely only the valve head needs replacing. Double check by putting your finger inside the opening on the valve head, you will feel a pin in there, if this does not move as you twist the valve from open to closed position then the valve needs replacing. (If it moves freely as you turn the handle then its usually fine.)
With the head still off and the heating on is the rad now heating?
If the heating is still not working there is a small pin poking up out of the top of the valve which sometimes gets stuck. Try gently pushing down on it, it only moves a couple millimeters. If it does not move, with a pliers, very carefully try to free it by trying to lift it a little. You should be able to move it freely up and down a couple of millimeters and when you push it down it should lift itself back up again.
If it is able to move up and down easily and the heating is still not working you may have an air lock or further problems with the valve, but see how you get on with that for the moment.

kelbal

thanks for the lengthy reply K, I'll give your suggestions a try

kelbal

Took the valve head off and gave the small pin a bit of a jiggle up and down - got it going again.
thanks again for the advice, friend is nice and warm again and very appreciative