New valve, old radiator, matching size

[TNGH]

Hello,

Some searching has presented a few similar threads, but not clear enough for me to understand the solution to my problem.

I have old radiators. One of the TRVs on one radiator was corroded closed and the lockshield at the other end leaks. I picked up a 15mm TRV and lockshield from Screwfix (for £6 - insane price). Replacing the TRV was easy enough. I used a freezing kit to avoid draining the system, very cool. When I went to replace the lockshield, I found the fitting to the radiator was a lot bigger than the valve and tails that came with it. I can't now easily get to the inside of the fitting, because my freeze thawed. The outside measurement of the nut is about 30mm, so I guess the inside is 3/4" or 1" - perhaps someone knows which is more common where it's not 1/2"? Photo included.

Untitled

• TNGH
• 22 Nov 2014
• 1

My question is: what is the easiest/cheapest way for me to replace this lockshield? Which parts do I need (with a minor preference to use the 15mm lockshield I already have). I think the answer may involve a bush, but I can't picture the obvious solution.

Thanks in advance for any advice.

 

[ALCPlumbing]

It'll be 3/4" on the connection to the radiator insert. You need a special key to remove the part within the radiator and then replace it with the newer 1/2" by 15mm compression styled insert. Otherwise you can still buy lockshield valves that will be 15mm compression on the pipe connection and 3/4" on the radiator connection. This way you won't need to remove the tail from the radiator.