Suggestions on what fittings to use to convert old radiator valves to 15mm TRV's

SchrodingersCat

Hi,

I am currently in the process of adding 15mm TRV's to our old radiators.

I am going to have to drain the system, remove the old valves, and replace them with the 15mm TRV valves.

My issue is that I dont know what fitting I need on both the radiator side, or the pipe side.

One of the radiators must have had an upgrade in the past, as it already had a suitable valve and lockshield fitted on the inlet and outlet:

It looks like the tailpiece on the radiator was swapped to support a 15mm connection on one end. But im not sure what fitting is on the radiator side. It appears to be threaded into the radiator, and is ~21mm in size. What would I ask for to get a couple of these adapters?

Secondly, any suggestions on how to connect the other end of the TRV valve?

SchrodingersCat

After a bit more research, I am leaning towards getting either these radiator tails:

and cutting them to size or these:

Im still trying to figure out what to do on the pipe side.

mikewest

Have you bought the TRVs already? If not find out the best plumbing / hardware suppliers in your area and check out if they have a selection in stock. Then drain the system down , pull off the different type valves you need to replace (one of each), take these with you and get TRV's and adaptors as necessary for all from your local suppliers. Also get plenty of PTFE tape and paste. Good luck and keep checking for leaks afterward with a refit.

stephenmarr

Buy Female TRV's

google image them it will be a straight replacement

https://www.ephcontrols.com/wp-content/uploads/2017/07/EMTRVBF15-1024x1024.jpg

SchrodingersCat

Thanks for the suggestions stephenmarr & mikewest.

The hardware place that I went to didn't seem to have any female TRV's, so I ended up taking a bit of a shot in the dark and ordering this TRV:

which had a 1/2" tail for the radiator already, and a 15mm compression fitting on feed end. Along with it I bought a 1/2" coupler:

along with plenty of ptfe tape and Boss White. I also got a spanner for undoing the old tail from the radiator:

The end result for one of the radiators is shown below.

Working with old gun-barrel pipework is a pain, there is very little give in it. Thankfully everything came together and there doesn't appear to be any leaks yet. 🤞

Thanks for the help 😁

I still have one outstanding concern:

As I am not using the 15mm compression fitting on the TRV (the olive), but instead am using a 15mm coupler to the 1/2" gun-barrel, will that do? i.e. is this a suitable method to join them?