Hi, im new here but would appreciate some advice on a strange boiler fault I'm experiancing.
With boiler in summer position H/W works fine, boiler fires and flame/temp/flow is maintained. When in Winter position (H/W + C/H) and boiler thermostat set to 3/4, heating fires up and runs for some time without issue. If H/W is demanded, boiler flame dips momentarily then recovers and water runs hot, when H/W closed, flow/heat diverts back to C/H. All good so far.
The 'fault' symptom is that after the boiler has been running for a while in the winter position at 3/4 temp, the burner sometimes shuts down but pump and fan continue running and the only way to start the burner up again is to switch the boiler off and on, boiler then ignites and normal operation resumed. Also sometimes the burner shuts down when hot water is demanded, on/off resets this.
If you reduce the boiler temp dial to 1/4, the burner goes out but doesnt re-ignite when the temp dial is raised or when hot water is demanded, but fan and pump continue to run until you switch of and on again.
During the time the boiler is working as 'normal' it fires up and shuts down on the room stat as normal. when the fault occurs (burner out), the room stat is calling for heat but burner doesnt ignite.
Pump/Fan/AP switch seem ok, Flue clear.
HW Thermsitor seems ok as hot water fine
Main Ctrl board replaced but fault persists
CHW Thermister replaced (room temp resistance 11.2k)
Power PCB seems ok?
Any ideas/suggestions greatly appreciated.
With boiler in summer position H/W works fine, boiler fires and flame/temp/flow is maintained. When in Winter position (H/W + C/H) and boiler thermostat set to 3/4, heating fires up and runs for some time without issue. If H/W is demanded, boiler flame dips momentarily then recovers and water runs hot, when H/W closed, flow/heat diverts back to C/H. All good so far.
The 'fault' symptom is that after the boiler has been running for a while in the winter position at 3/4 temp, the burner sometimes shuts down but pump and fan continue running and the only way to start the burner up again is to switch the boiler off and on, boiler then ignites and normal operation resumed. Also sometimes the burner shuts down when hot water is demanded, on/off resets this.
If you reduce the boiler temp dial to 1/4, the burner goes out but doesnt re-ignite when the temp dial is raised or when hot water is demanded, but fan and pump continue to run until you switch of and on again.
During the time the boiler is working as 'normal' it fires up and shuts down on the room stat as normal. when the fault occurs (burner out), the room stat is calling for heat but burner doesnt ignite.
Pump/Fan/AP switch seem ok, Flue clear.
HW Thermsitor seems ok as hot water fine
Main Ctrl board replaced but fault persists
CHW Thermister replaced (room temp resistance 11.2k)
Power PCB seems ok?
Any ideas/suggestions greatly appreciated.
