No.1 U.K. Professional Trade Forum, Plumbing, Gas, Electric, Tiling and Joinery Forum

I have a Siemens thermostatic valve. Similar to this, but my valve is horizontal:

https://www.wolseley.co.uk/product/siem ... me-plated/

It used to have a very slow drip. Now it has started to increase.

AFAIK, the screw fitting to the rad is as tight as I can make it. The drip seems to be coming from the air holes in the valve. (Remember that the valve is horizontal.)

Question: Is it easy to unscrew the rotating part without needing to unscrew the whole valve from the rad?

If yes, how do I do that? And how do I fix the leak?

Thanks.

Hi, if you push down slightly on the plastic part toward the valve then locate and unscrew the chome ring beneath it it will come off.
there is a brass nut beneath that where it may be dripping from.
best result is to change whole valve as there only £7-20 each

Isnt there a rubber O-ring? Mind you I no idea if you can buy it seperately.