This is slightly difficult to explain. I've just bought a Honeywell TRV
head (TRH4M30WBG) to fit to a valve that previously had another make of
head on it. The thread (30mm) is correct but the central nut on the
valve is smaller than the internal TRV body is designed for, so the body
tends to turn when the head is adjusted. Is there an adapter available?

On 12/03/2018 19:22, wrote:
This is slightly difficult to explain. I've just bought a Honeywell TRV
head (TRH4M30WBG) to fit to a valve that previously had another make of
head on it. The thread (30mm) is correct but the central nut on the
valve is smaller than the internal TRV body is designed for, so the body
tends to turn when the head is adjusted. Is there an adapter available?

Not off the shelf. Whether you could make something out of shim, I
wouldn't like to say. But the odds are that the axial positioning will
also be wrong. You *might* get away with it. How much is your time worth?

If the original valve is old, and/or not Drayton or similar quality I
would not spend long on it.

wrote:

This is slightly difficult to explain. I've just bought a Honeywell TRV
head (TRH4M30WBG) to fit to a valve that previously had another make of
head on it. The thread (30mm) is correct but the central nut on the
valve is smaller than the internal TRV body is designed for, so the body
tends to turn when the head is adjusted. Is there an adapter available?

I think thee are 28-30mm adapters from Myson, and IIRC some old
honeywells may even have been rebadged mysons ...

e.g.

https://www.amazon.co.uk/Myson-adapter/dp/B01CEVYC8S

at that price I'd be looking elsewhere, but you get the picture.

On 12/03/2018 22:09, Andy Burns wrote:
wrote:

This is slightly difficult to explain. I've just bought a Honeywell TRV
head (TRH4M30WBG) to fit to a valve that previously had another make of
head on it. The thread (30mm) is correct but the central nut on the
valve is smaller than the internal TRV body is designed for, so the body
tends to turn when the head is adjusted. Is there an adapter available?

I think thee are 28-30mm adapters from Myson, and IIRC some old
honeywells may even have been rebadged mysons ...

e.g.

https://www.amazon.co.uk/Myson-adapter/dp/B01CEVYC8S

at that price I'd be looking elsewhere, but you get the picture.

The thread is the right size, the problem is that the body turns on the
valve because the nut is too small to engage with the inner part of the
body.

On 12/03/2018 19:31, newshound wrote:
On 12/03/2018 19:22, wrote:
This is slightly difficult to explain. I've just bought a Honeywell
TRV head (TRH4M30WBG) to fit to a valve that previously had another
make of head on it. The thread (30mm) is correct but the central nut
on the valve is smaller than the internal TRV body is designed for, so
the body tends to turn when the head is adjusted. Is there an adapter
available?

Not off the shelf. Whether you could make something out of shim, I
wouldn't like to say. But the odds are that the axial positioning will
also be wrong. You *might* get away with it. How much is your time worth?

If the original valve is old, and/or not Drayton or similar quality I
would not spend long on it.

It's a new Pegler or Honeywell (I think) valve. The house has Evohome
HR92s on every radiator and towel rail but I decided that the airing
cupboard would be better with a regular "old fashioned" TRV and didn't
think to check what stops a TRV body from turning. I think the axial
stroke is OK so, if necessary, I'll have to make a widget.