my central heating temperature control does not work no matter what I set it at it just goes to full heat

john, February 2010

thankyou for your advice .c. got microswitch and water diaphragm had them fitted .everything works just great
once again thanks saved me cost of replacing boiler
john

john, March 2010

this is probably because the boiler thinks there is constant hot water demand because the domestic hot water microswitch is broken.
Try turning down the hot water temperature control, does it modulate the central heating too now?, also switch to summer only mode -the CH should be inoperative, but will stay on with this fault.
Cheap and easy to fix - get a new microswitch and wire it in. Replace the domestic hot water diaphragm while you are at it. Disconnect the mains first as the switch is live.

c, February 2010