I have a Halstead Wickes Combi 2000 boiler.
A month ago I was only getting domestic hot water when the central
heating was on, I traced this to a perished Diverter valve diaphram
and replaced the complete valve and everything was fine, I had hot
water back.
A month later and now its gone again? But different symptoms this
time.
If I turn on the domestic hot water the pin on the diverter valve moves
up as it should and operates the micro switches OK and the burners come
on. But the heating appears to go to the central heating circuit and
the radiators get nice and hot, the domestic hot water never gets above
luke warm.
The diverter valve appears to be moving but not diverting, any help
please? I'm confused.

I don't know if this is relevant but when I open up the Automatic Air
Vent bleed nothing comes out no water or air.

Thanks
Dave