Replacement thermostatic radiator valve

[pickledherring]

I have a leaking radiator thermostatic valve. However whilst the compression fitting for the incoming water pipe is 15mm (bottom), the compression fitting going into the radiator appears to be larger, perhaps 20mm (see first pic).

I can't seem to find any replacement valves which aren't 15mm for both compression fittings. The one recommended as a replacement is a Drayton RT212, which is 15mm for both fittings.

The old valve does say the compression fitting which goes into the radiator is 1/2 inch, which is nominally 15mm, even though it appears larger as seen in the picture.

My question is will the Drayton fit on both the copper piping and the radiator, even though the existing valve appears to have two different sized compression fittings? The existing valve is over 40 years old!

Thanks in advance.

 

[avonmouth]

You will be changing the whole thing and the tail that screws into the rad will be1/2 inch BSP and the same as in your pic.
To remove the existing tail you might need a hexagon rad spanner or insert a wide chisel/screwdriver and undo using grips.

 

[pickledherring]

Thanks avonmouth. So the Drayton RT212 is not suitable as the tail to the rad is smaller than 1/2 inch BSP? Is there a suitable valve you can recommend?

 

[avonmouth]

The Drayton RT212 has the same size tail as yours.It will be a straight swap.

 

[Madrab]

You are better off replacing the whole thing - rad tail included. The sealing faces on the 3/4" union that is currently in there will be mated to the current valve and trying to use a new union valve can sometimes be difficult getting it seal again.

The Drayton RT212

The RT212 has a 1/2" compression tail, not a 3/4" union?


Finding a TRV with a 3/4" union is much harder these days though there are a few. Drayton do a TRV4 with a 3/4"union but it uses a different compression inlet.


Better off just removing the old rad tail and fitting a new 1/2" one.