i have a problem in the cooler weather in that my boiler runs even when the controller is not calling for the boiler to come on ,to stop the boiler i have to turn it to 0 position ,i have changed the controller but it made no difference . anyone know where the problem lies?.

martin davie, October 2006

is it a 'y' plan system with one mid position valve or an 's' plan with two zone valves? you should be able to find them next to the hot water cylinder. If its an 's' plan you may find one of the valves is stuck open or the motorised head is faulty.

Paul, October 2006