Bolier problem

[PEB]

I have a Potterton Super Prima boiler 12 years old. 4 years ago motherboard replaced. Current problems
a) Boiler will only start up when hot water is set to come in at same time
b) Once temperature reached, it cuts out but will not come back on when temperature drops or when I increase the temperature manually by thermostat
c) Will not cut if ‘boost’ for an hour or two
d) Pump in airing cupboard continues for hours after heating and water has gone off

Any ideas?

 

[gas_man_gaz]

what type of system have ya got?

at a guess id say ya got a s-plan sys (2motorized valves in the airing cupboard) and ya heating valve isn't motoring over enough to make the microswitch, so ya ch will only work while you have got demand from the hw

is only a guess tho

 

[bengasman]

Would be my guess too.