Thermostatic radiator valve stuck

[melody44]

Have turned on heating and know that some of valves are stuck as rads not warming up. Last year a nice plumber showed me how to undo them and bash the pin inside to unstick them. But can't remember how to undo them - do I have to unscrew something or just yank the tops off.

I know its a long shot - they are Danfoss ones with cyclindircal plastic heads. Any ideas anyone?

There's a knurled ring where the thermostatic bit connects to the metal pipes. Unscrew this and the thermostatic head will come off. Then you'll see the metal pin. I would use pliers to gently free them. Don't bash them too hard.

and rather than trying to pull them out with pliers, push the pins gently down and let them spring up. It is usually the diaphagm inside that has stuck, not the pin. I find a large spoon in the palm of the hand is good, as it spreads the load and prevents the pin pounturing you, and also the curvature holds the pin in the middle and prevents it slipping sideays, as it might on a flat surface. If the pin goes sideways it will probably break off.

Before trying to refit the thermostatic head, turn it to its hottest setting, or it may be prevented from screwing down by pressing against the pin.

It may help to let a drop or two of WD40 run down the pin into its hole. Don't try and spray it; spray into a clean jamjar and pick a drop of the liquid up on the tip of a pencil.

BTW it is better not to screw the TRVs shut tight in summer. Assuming you have a room stat, or a programer (and you should have both if you don't want to waste money) then the CH will not come on until you turn it back on in autumn; and unless you have a faulty motorised valve, hot water will not leak past into the CH pipes. If the TRVs are set to 18C or whatever during summer, they will move slightly in summer at night depending on the weather, which will help stop them seizing.

[[http://www.danfoss.com/United_Kingdom/Products/Categories/Group/HE/Thermostatic-Radiator-Valves/Domestic-Sensors-Valve-Bodies-and-Lockshield-Valves/9fb1c4ed-eb6a-4644-b4c6-14aadfc6056a.html probably one of these.
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The Danfoss RAS-C2 is a very good modern one, and about half the price of the fashionable Drayton TRV4, which used to set the standard for high quality valves.

Oh thanks v much. The crucial info is that I have to unscrew something - didn't want to try it in case water started gushing everywhere. This did once happen to me by accident and ended up trying to squash valve back on while boiling hot water pumped out all over the place.

Thanks esp pigletjohn for detailed valve maintenance descriptions. Will have a go and report back if successful.

Thank you for the help this thread has provided. Just removing the thermostatic valve and putting WD40 on the holes has feed up my pin and the radiatior (and my son) are warm again!