TRV pin not springing back

29 Jan 2017
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United Kingdom
I have a cold radiator, so I removed the TRV head to see if the pin was stuck. It's not, I can move it back and forth with pliers, but when I push it in it is not springing back.

The TRV head is an old Danfoss RAVL valve which pushes on and is then secured by a compression clip and screw (shown in photo), rather than a screw on head. I had hoped that either unsticking the pin or replacing the TRV head would help (this is the only one I could find which would fit:, but if the pin isn't springing back, I'm guessing this won't help?

My question is, do I need to replace the valve body for a new one (and one which would allow fitting of a more modern screw fit valve head) or is there a way to get the pin to spring back again?

Many thanks
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When my danfoss TRV used to stick I tapped the pin gently with a hammer and sprayed WD40 on it it eventually freed itself. If the platform inside the head moves back and fore when the adjuster knob is turned then the head is okay. I changed mine for more modern looking ones that I bought online, google that head there are plenty of pictures to help. I don't think that one you have linked to will fit. If you want the screw on type heads then you will have to change the valve. Of course I suppose the spring could have broken but I have not known that happen. I have lived in two houses now with that type of valve but as I changed all the rads in both houses I also changed the valves to the more modern screw on type
Thanks for your reply. I think that head I linked to should fit. Here's another image of the same item, showing more detail of the attachment type:

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