Baxi Combi 133 HE Pus, constant heating when not selected?

I have the 100HE which is almost identical. I have the same problem. When in winter mode no matter what the manual timer is set to, the boiler fires up and turns on the CH. I've also checked the 3 way valve actuator and it seems to be working fine. When in winter mode the actuator pushes the valve all the way in. When hot water is switched on or when in summer mode it releases the valve. It seems that these are the only 2 positions the actuator has - is that correct?

Also the PCB is quite hot - is this normal or does this suggest a faulty PCB that would cause the problem above?

Andy Hoyle
October 2008