Have had the programer replaced, motorised valves are working correctly (supposedly) Immersion tank thermostat also replaced. Bolier fires up when heat or water settings on programer are off. Also water very hot despite boiler thermostate being turned low (tried all positions, water just remains very hot and noisy, kettleing. Have now resorted to controling system by mains switch! Any advice please, apart from new boiler

Chris, June 2009

Recheck your wiring on programer for Boiler on/off, kettleing check pump flow rate and gas rate and is the pump overun thermostate working O/K plus the main thermostate they are held together in same file on boiler, also depending the age of your heating system may need a powerflush, but try some fenox mb1 as well this should help noisey boilers!

Ray Dawson, July 2009