HVAC Questions? Ask an HVAC Expert for Answers ASAP
Hello, please can you tell me the make and model of your thermostat and timers?
Please can you post a photo of the timers so that I know what you're referring to?
Do you have motorised valves in this system? If so, it's possible that one or both or them are sticking open.
Either the thermostat receiver unit is malfunctioning, and calling for heat when it shouldn't, or the boiler is faulty.If you turn off the receiver, does the boiler still ignite? If so, I would carry out a further check, which is to disconnect the receiver from the boiler, in case its relay is fused. In either case, if the boiler no longer ignites randomly, then the fault is in the receiver unit. If the boiler ignites when the receiver is disconnected, then the fault is in the boiler.