Fitting new TRV head

[Mike C]

Hi,

the sensor head has broken off on one of the TRV's and can't be repaired. I have bought a like for like replacement TRV although it is only the head I need. I have tried fitting the head on by just screwing it on to the old valve with the securing ring but it doesn't seem to work and the radiator is just on full with moving the head having no affect whatsoever. Am I doing something wrong here and is it not as starightforward as screwing on a new head or could there be a problem elsewhere in the old valve?

Cheers

 

[Best]

What make is it? Are you sure you have identical make & model?
You have to turn the new head full on before you attempt to push it into correct position before turning the nut.
You might have a faulty trv body & will need to replace whole trv

 

[Mike C]

It is a Bulldog and is identical. It has probably been like this for some time, maybe years ( I have recently moved in). Could the pin be stuck or stiff ?

 

[Ch4 plumbing]

It is a Bulldog and is identical. It has probably been like this for some time, maybe years ( I have recently moved in). Could the pin be stuck or stiff ?

Normally if the pin is stuck the valve won't work and the rad is cold, as above its prob time go change the whole thing.

 

[Best]

Try hitting the pin a few gentle taps with a hammer. If it still doesn't turn off with the head, then replace the whole valve.
I have seen a few of the more expensive version of the Bulldog valve failing to turn off except by using the wee service cap supplied with them. Very odd, but I just had to replace the body

 

[BadgerBoilerMN]

I live in Honeywell country but stated they are bulky and commercially oriented. For residential I prefer the Danfoss line but don't have any stickers since we started using Fernox on all hydronic systems.