Trying to replace my British Gas thermostats for radiators !

123ray

Hi have old style British Gas Thermostats , many are broken after years of service I am trying to locate replacements  for them either with a new model with the same fit or some old stock of said model. I don't have the money to get a plumber out as energy bills are so high atm so this is my best option. I have tried a few other models without any luck. 

[Deleted User]

That's not a thermostat - it's a TRV head.

IIRC, British Gas badged ones are interchangeable with Drayton TRV4 models.

molerat

Can you post a picture of the valve on the radiator.  They look pretty standard heads, are you sure there is not part of it left on the rad ?  A  few years back I replaced some of mine and it was literally screw off screw on.

edit.  Google shows a picture of that head.  You need to unscrew the silver metal ring from the radiator valve.  Standard replacement.

Mister_G

Yes, they are the same as these

https://www.screwfix.com/p/drayton-rt212-white-trv-sensing-head/569HG?tc=VT2&ds_kid=92700072615374555&ds_rl=1249404&gclid=Cj0KCQiAyracBhDoARIsACGFcS5Xd0FsSIJNJhSnBfyJIyw2qsjhyrPs38CPUgOyyn6rPOUc31ON0HcaArsqEALw_wcB&gclsrc=aw.ds

BUFF

If they are M30 x 1.5mm fitting, as Mister_G suggests, then there are many options available from many manufacturers. It is probably the most common fitting these days.

Mister_G

Be aware that the earlier Drayton TRVs (TRV1 & 2) had the smaller M28 thread - as I discovered when retrofitting my Drayton Wiser smart TRVs!  

Fortunately there are M28 to M30 adaptors available.

BUFF

if it is M28 then there are still several manufacturers that make TRVs with that fitting.

Qyburn

If they're that old you then check the valves are working smoothly (press the pin).  In time they are very likely to be sticking and may well not work properly until the valves are replaced as well.

Arthurian

Do you have to drain down the whole system to replace TRVs?  I have a couple which are sticking, but wary of draining down in case that stirs up more trouble.  Thanks.

mysteryUser

Arthurian said:

Do you have to drain down the whole system to replace TRVs?  I have a couple which are sticking, but wary of draining down in case that stirs up more trouble.  Thanks.

The heads can be swapped without draining.

The body (connected to the pipes) involves disconnecting the area full of water. For most DIYers, draining down the system is probably wise. I had a plumber swap one of mine without draining the system. It's also possible on open vent systems to bung the air inlet and generally not much water will come out. You can also get freeze kits / systems which freeze the water to allow you to remove without draining -  I had a very bad encounter using a can style freeze system, TRV removed... then the block of ice shot out and hit the ceiling followed by a pretty large water feature. 

matelodave

mysteryUser said:

Arthurian said:

Do you have to drain down the whole system to replace TRVs?  I have a couple which are sticking, but wary of draining down in case that stirs up more trouble.  Thanks.

The heads can be swapped without draining.

The body (connected to the pipes) involves disconnecting the area full of water. For most DIYers, draining down the system is probably wise. I had a plumber swap one of mine without draining the system. It's also possible on open vent systems to bung the air inlet and generally not much water will come out. You can also get freeze kits / systems which freeze the water to allow you to remove without draining -  I had a very bad encounter using a can style freeze system, TRV removed... then the block of ice shot out and hit the ceiling followed by a pretty large water feature. 

My Bro had a similar experience with a home freezer kit.

there are ways of changing the valves without draining down the system - there are a few YouTube vids on the subject but you need to have your wits about you if you decide to do it if you want to avoid any mishaps.

I've managed to get valves working again with a little liquid silicone lubricant or even WD40 (better than oil if you dont know what the seals are made of) dribbled around the pin and then working the pin up and down a bit until its working again. Perhaps a gentle twist with a pair of pliers to get it moving.

As in all things be gentle you dont want to break anything with the heating system full of water