Replacing dead TRV

[DerbyBorn]

Mike Clarke wrote in news: [e-mail]:

Can you compare it with another of the same make?

[JoeJoe]

Just a quick update...

Bought a new TRV head and replaced the old one.

Everything now works as it should again!

many thanks for the tip.

[DerbyBorn]

Glad you got a match.

[Andy Burns]

How standard are they across manufacturers?

I've got some new Myson ones and some 30ish year old Honeywell ones (removed) they both have a 30mm thread with "octal" positioning grooves, and about 4mm of travel from min to max, but how much travel is there in the wax capsule?

The Honeywell ones have an internal threaded "calibration boss" around the pin, which presumably pre-loads the valve spring?

[John Rumm]

Did you just replace the head, or did you need to swap the wet bit as well?

[Andy Burns]

Looks like they're not even standard for a given manufacturer ...

[DerbyBorn]

Andy Burns wrote in news:e9375oFl6ogU1 @mid.individual.net:

I wonder how much movement a couple of degrees temp gives?

[JoeJoe]

Just the head with this one:

Took a chance with it. Worse case I was going to replace the lot.

[DerbyBorn]

But does it actually turn the radiator down in response to the room temp?

[DerbyBorn]

I often wonder about this. Mine are sensitive to such a small arc of a turn. Just fitting another head and not chacking is a waste of time. (I uses a stethoscope to listen for the flow rate changing when turning it to find the optimum setting i a warm room)