The Boiler will fire up ok & stay on for a half an hour or an hour or so but it eventually goes off on it's own. It seems that calling for Hot Water causes the Burner LED to go off; hot water comes out at first but then quickly goes cold (within a minute or 2). Turning the hot water tap off again does not cause the Boiler to ignite again so there is then no Central Heating; the Burner LED stays off.
I have checked that the thermistor changes value when hot & cold (but don't know what values it should be -does anyone know?)
The Primary Flow Sensor 'piston' does generally go up and down & switch the microswitch (not sure if it did during this test, will check).
The pump does run (I've listened to it and taken the cap off the end & seen it spinning {when it slows down; it's too fast to see when it's running normally}). Mains is getting to the pump when it's running (of course).
I notice that there's an inline filter inside the 'group set'; does this need to be cleaned occasionally? I think this is only for DHW?
Could the problem be overheating when calling for DHW? I haven't tested the 'Safety Overheat Thermostat' yet, I must do that!
I think I've tested that all the microswitches go off & on (0 Ohms) including the 'Air Pressure Switch'.
The other symptom I was (and probably still am) getting is that when the CH Timer has switched to off (after the CH has been running ok), maybe 1 hour later, a Relay on the PCB clicks, the Primary Flow Sensor 'plunger' raises, switches the Microswitch then the Relay goes off again & this cycle continues forever!
I've been trying to eliminate verything else to decide if it's a PCB fault as I don't want to spend £150 on a new PCB if that's not the cause of the problem.
Does anyone know if it's possible to get hold of a Circuit Diagram for the PCB & is there such a thing as a proper Service Manual for these Boilers (I have the 'Installation Manual')
Any thoughts? Thanks for reading this.
'The Prisoner'
(maybe a Meteorological Balloon will come and fix it for me...)
I have checked that the thermistor changes value when hot & cold (but don't know what values it should be -does anyone know?)
The Primary Flow Sensor 'piston' does generally go up and down & switch the microswitch (not sure if it did during this test, will check).
The pump does run (I've listened to it and taken the cap off the end & seen it spinning {when it slows down; it's too fast to see when it's running normally}). Mains is getting to the pump when it's running (of course).
I notice that there's an inline filter inside the 'group set'; does this need to be cleaned occasionally? I think this is only for DHW?
Could the problem be overheating when calling for DHW? I haven't tested the 'Safety Overheat Thermostat' yet, I must do that!
I think I've tested that all the microswitches go off & on (0 Ohms) including the 'Air Pressure Switch'.
The other symptom I was (and probably still am) getting is that when the CH Timer has switched to off (after the CH has been running ok), maybe 1 hour later, a Relay on the PCB clicks, the Primary Flow Sensor 'plunger' raises, switches the Microswitch then the Relay goes off again & this cycle continues forever!
I've been trying to eliminate verything else to decide if it's a PCB fault as I don't want to spend £150 on a new PCB if that's not the cause of the problem.
Does anyone know if it's possible to get hold of a Circuit Diagram for the PCB & is there such a thing as a proper Service Manual for these Boilers (I have the 'Installation Manual')
Any thoughts? Thanks for reading this.
'The Prisoner'
(maybe a Meteorological Balloon will come and fix it for me...)