DIY Doctor UK DIY Forums

I have a modern boiler and controls but very old radiator thermostats, a number of which no longer work. I have taken the heads off and the pins move freely enough, so I thought changing the heads should sort this out. Unfortunately, the fitting does not seem to conform to modern standards and I am unable find any new heads to fit. Local plumbers merchants just stare at me blankly when I take an example thermostat in. Picture attached. Can anyone advise what I can replace these with?

Hi alanchafer,
Suggest you remove one head as a pattern, measure the thread diameter and the depth from the actuating plunger in the head to the mating shoulder. Purchase different heads from places like Screwfix or Toolstation and see if they match - if not you can always return them for a full refund.
Regards S

Thanks, I have been trying that but have yet to find one that fits.

Hi alanchafer,
Even if someone could identify the manufacturer there’s a good chance the design will have changed. You may have to bite the bullet and fit complete new valves.
Regards S

I have found a company that sells converters from the old 28mm size to the new 30mm, allowing me to then fit a modern valve.
https://www.heatingcontrolsonline.co.uk ... aptor.html
I have ordered one up to try it out and if successful will follow this up with a bulk order for the remaining radiators.

Hi alanchafer,
Well done, I didn’t know such things existed. Please do let us know how it all works out.
Regards S

Well done, what I did was get eQ-3 electronic heads which come with a pack of adaptors, I still have the adaptors so could measure and see if they match.

Instructions show RA and RAV both clamp to body, and RAVL which seems to clip on.

The sample adaptor and valve from
https://www.heatingcontrolsonline.co.uk ... aptor.html
fitted easily and I have now replaced all nine valves successfully. Picture attached of adaptor in place.

Hi alanchafer,
Thanks good to know that a stand alone adaptor is available and that they work.
Regards S