Central Heating Problem - Potterton Boiler

[DK]

Hi,

Apologies if I am covering old ground. My problem is the central heating fails to operate when both the programmer and the room thermostat have been switched on. The hot water works fine everytime and has never been a problem.
The only way to get the CH to work is to operate the manual override on the two way valve in the airing cupboard. I am not sure what the technical term is. but it has outlets Port A and Port B etc.
I am pretty sure getting the CH to work this way also enables the HW aswell as the water seems unusually hot in late at night.
Can anyone point me in the right direction?

Cheers

Dave

 

[bster]

new valve or motor or head or entire unit.

 

[DK]

Looking through the forum, its obviously a common problem with Potterton/Myson systems and most of the experts suggest what you said.
Cheers for that.