switchmaster mid position valve problem?

[pabs]

hi,
i have a 3way mid pos valve and for some reason yesterday it appears to have stopped working correctly!
when the valve is set to hot water or central heating & hot water the boiler fires up and it works correctly but when its just on ch the boiler doesnt fire up and i have no heating! the room thermostat works as i have tested it on the ch & hw position and i get radiators on but no heat from radiators in ch only mode!

 

[Agile]

I think that you have correctly deduced that its failed !

What are you going to do next?

 

[pabs]

good question! any ideas?

would you agree its definitely a valve fault?

 

[Agile]

It sounds very likely that the head is not powering the call for heat to the boiler and pump when it reaches the CH only location.

You might be able to fiddle with it but commercially I would always replace the whole valve or the head only if an appropriate type like a honeywell with a dimple.

Tony

 

[ChrisR]

Switchmaster Midi - aren't they all the obsolete blue or brown with white dial ones??

If so you'll be changing the whole valve, and rewiring, with some pipe adjustments too