How to remove old Boss TRV Body from Valve?

[g0wen]

I’ve got a radiator valve of unknown age, with a TRV head on it labelled BOSS. I’ve been able to partially disassemble the TRV body, but cannot see a clear way to remove the it from the valve properly.

I have a Tado TRV to put on and would like to see if it can fit on the existing valve, as otherwise I’ll have to replace the whole valve.

I’ve attached some pictures of the TRV body in question. If anybody can explain how to remove it that would be very useful!

 

[CBW]

Have you tried unscrewing it, where it meets the valve? Have you tried pulling it off?

 

[RandomGrinch]

Purely looking at it as a mechanical fitting - it appears to me as if the bottom ring rotates upwards towards the TRV head. Once this (locking) ring is out of the way, the TRV head could be pulled off of the valve.
Working in a broadly similar way to a collet.

However, this is guesswork, and I could be completely wrong!

 

[g0wen]

Sorry, it would help if I’d said what I’ve tried so far wouldn’t it!

I have tried unscrewing it where it meets the valve, but it does not turn beyond a slight play that is blocked when the plastic meets the metal fins(?) that stick out from the valve. It doesn’t feel like it is unscrewing, just pivoting around the valve slightly.

Pulling up lifts the whole valve and radiator before anything happens to the TRV body - it’s possible this is just very stuck, needing more force than I’ve been willing to apply so far.

I believe you’re right about the lower part locking the upper part in place, but it’s not clear in the photos that the two parts appear to be interlocked, so the lower one can’t rotate without the upper rotating too - I’ll put up a better photo tomorrow.

 

[CBW]

Perhaps it needs a removal tool?
Boss instructions

 

[RandomGrinch]

I believe you’re right about the lower part locking the upper part in place, but it’s not clear in the photos that the two parts appear to be interlocked, so the lower one can’t rotate without the upper rotating too

Have you tried rotating it both ways?
I.e. from the original photo, turning it clockwise (from underneath) towards the head. Or pulling the ring up independently?
As the worst outcome may be replacing the valve entirely, getting destructive with it is definitely an option!

 

[gas112]

Grinch is right it ring turns slighty then valve pulls off its just stuck so just snap what is left of the valve off

 

[ianmcd]

As @gas112 just break off what is left, unlikely the new sensor will fit, new complete valve time

 

[Elkato531]

That one doesn't twist. The plastic ring locks the head on to the valve. It should just pull upwards to release.

As most trvs use a screwing locking ring these days, its likely the to need the whole valve.