Hello,
Forgive the long post - I'm hoping that putting in the detail will help...
My 1999 Gloworm boiler's main PCB took a turn for the worst and burst into flames in the middle (near the overheat cut-off connector in the midle).
My plumber replaced it with a modern version of the PCB for a princely £370 and it appeared to work fine for a while, however now it exhibits the following fault:
In the morning and evening (two on the trot now) - i.e. when the system is cold, the boiler will fire up, reach temperature and stop the burner (all normal). However it will not fire up again when the temperature of the pipes has gone back down (I mean I can hold my hand on the pipe - when it's up to temperature it's too hot to touch for long).
To get the burner back on I have to remove power from the boiler (either by switching off the 3A switched spur in my airing cupboard that supplies the central heating/programmer/pump/3-way midport valve or by turning the knob on the front of the boiler to zero and back up again).
After repeating this process some 10-15 times the boiler operates normally (it's on now and keeping the house nice and warm, but I had to keep cycling the power to the boiler for about 30-40 minutes).
Here's an idea of the timescales I'm talking about (perthaps it might give a clue as to what is happening):
Power on: (no lights). 13 seconds later, fan starts, 7 seconds later the burner fires (manual says it's ten, but I timed it), 2 seconds later the burner light is lit.
19 seconds later the burner went off (no lights). I waited 7 minutes and it didn't come back on - in that time the pipes to the boiler were still warm, but I could hold them without any discomfort. Upon resetting the boiler, the process repeated and the pipes returned to normal (too hot to hold) temperature.
The time between the burner starting and cutting out seems to vary (but I've not stood there with a stopwatch every time). It appears (anocdotal evidence) take longer to cut off if the temperature on the boiler is set higher - suggesting that it thinks it's up to temperature.
My plumber is going to replace the wiring loom (another £100 odd quid then no doubt) since it was damaged by the electrical fire.
My problem is that he doesn't appear to know the root cause of the original PCB failing and now the new one is misbehaving - is he going to just replace parts until I might as well have bought a new boiler?
Can anyone suggest why the boiler is not firing up again after it has cooled? (Yes the room stat is still calling for heat - the pump is still running and power is still going to the boiler).
Can anyone suggest why the PCB might have caught fire in the first place? The plumber says that dry joints on that connector are common, but arcing/fire isn't.
Thanks in advance for any ideas,
Darryl.
Forgive the long post - I'm hoping that putting in the detail will help...
My 1999 Gloworm boiler's main PCB took a turn for the worst and burst into flames in the middle (near the overheat cut-off connector in the midle).
My plumber replaced it with a modern version of the PCB for a princely £370 and it appeared to work fine for a while, however now it exhibits the following fault:
In the morning and evening (two on the trot now) - i.e. when the system is cold, the boiler will fire up, reach temperature and stop the burner (all normal). However it will not fire up again when the temperature of the pipes has gone back down (I mean I can hold my hand on the pipe - when it's up to temperature it's too hot to touch for long).
To get the burner back on I have to remove power from the boiler (either by switching off the 3A switched spur in my airing cupboard that supplies the central heating/programmer/pump/3-way midport valve or by turning the knob on the front of the boiler to zero and back up again).
After repeating this process some 10-15 times the boiler operates normally (it's on now and keeping the house nice and warm, but I had to keep cycling the power to the boiler for about 30-40 minutes).
Here's an idea of the timescales I'm talking about (perthaps it might give a clue as to what is happening):
Power on: (no lights). 13 seconds later, fan starts, 7 seconds later the burner fires (manual says it's ten, but I timed it), 2 seconds later the burner light is lit.
19 seconds later the burner went off (no lights). I waited 7 minutes and it didn't come back on - in that time the pipes to the boiler were still warm, but I could hold them without any discomfort. Upon resetting the boiler, the process repeated and the pipes returned to normal (too hot to hold) temperature.
The time between the burner starting and cutting out seems to vary (but I've not stood there with a stopwatch every time). It appears (anocdotal evidence) take longer to cut off if the temperature on the boiler is set higher - suggesting that it thinks it's up to temperature.
My plumber is going to replace the wiring loom (another £100 odd quid then no doubt) since it was damaged by the electrical fire.
My problem is that he doesn't appear to know the root cause of the original PCB failing and now the new one is misbehaving - is he going to just replace parts until I might as well have bought a new boiler?
Can anyone suggest why the boiler is not firing up again after it has cooled? (Yes the room stat is still calling for heat - the pump is still running and power is still going to the boiler).
Can anyone suggest why the PCB might have caught fire in the first place? The plumber says that dry joints on that connector are common, but arcing/fire isn't.
Thanks in advance for any ideas,
Darryl.
