How to change this TRV

[LeeUK]

Ever wished you hadn't started something!

On a whim I got a double radiator to replace a single.

The current TRVs are I presume 3/4 and the tails on the replacing rad are 15mm so I am going to replace the TRV
Thing is, its not the usual 15mm compression its slotted onto the pipe -

When I take off the TRV what will I see - just the 15mm pipe I can slot a nut and olive onto or will I need to cut the pipe?

When I say ever wished you hadn't started, I now have that black trail on a NEW carpet!

 

[Phill Peck]

You take the tail out of your old rad and put it in the new one.

 

[LeeUK]

Hmm, not sure. BTW the pic above is of another rad.
This is one reason why im changing

 

[dilalio]

Old rads and TRVs will have 3/4 unions new tails and TRVs are usually 15mm compression with olives.
Did you buy the valves with the rad?
Unions are often easier if the pipes are fixed because rad can slide between them whereas nuts and olives require you to be able to pull valves apart to slot the tails into the valve at each end... which can be pretty tricky on your own with a large rad!

 

[LeeUK]

replacing rad tail -

 

[LeeUK]

Job aborted!
Old rad is back on

 

[Phill Peck]

Hmm, not sure. BTW the pic above is of another rad.
This is one reason why im changing

Not sure about what?

 

[Doggit]

Okay, someone's got to ask; what went wrong.

 

[LeeUK]

The existing TRV started dripping so had no option than to put the rad back on
I didn't want to take the tails off the old one partly for this reason and in case they didn't go back on the old one.

I still dont know that I will get if I take the old TRV off, will there be an olive there or straight pipe for me to put a standard 15mm olive etc on?
If so I'll just get a new TRV
I've never used this type of fitting before.

 

[Doggit]

There'll be an olive at the top of the copper pipe, but you'll need to cut through it with a junior hacksaw, and then prise it apart before you cut all the way through it. Now it's not uncommon for the TRV to leak, as the pin doesn't always get pushed right down by the head. In the new TRV box, there will have been a plastic head that you can screw on the TRV body which will push the pin down, and stop it leaking - with a bit of luck, it'll work on the old head just as well.

 

[LeeUK]

There'll be an olive at the top of the copper pipe, but you'll need to cut through it with a junior hacksaw, and then prise it apart before you cut all the way through it. Now it's not uncommon for the TRV to leak, as the pin doesn't always get pushed right down by the head. In the new TRV box, there will have been a plastic head that you can screw on the TRV body which will push the pin down, and stop it leaking - with a bit of luck, it'll work on the old head just as well.

Thanks, much appreciated. I am going to give it another go........ at some point