Thanks for your help on this. Having done all the checks mentioned, I think you're right and it's a stuck valve. Having a new one fitted by someone who hopefully knows more than me!
Cheers
hi
Looking at this thread last night, I was most impressed by the help, and wondered if I could put forward my problem.
I have a Worcester Danesmoor 20/25 installed about 8 years ago. It has a Honeywell control box with, what I assume is the 3-way valve mentioned. The thermostat is a wireless...