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Andrew Smith
Andrew Smith, Construction Worker
Category: Plumbing
Satisfied Customers: 3586
Experience:  30 years experience in construction, City and Guilds qualified.
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I've got a Glow Worm Betacom 30C installed in 2010.In

Customer Question

Hi I've got a Glow Worm Betacom 30C installed in 2010.
In the past on a few occasions I've experienced the badly designed condensate/sensor issue causing boiler lockout, but managed to investigate and resolve the problem with a simple dry down of the end of the spade terminals in the blue cap.
This morning, we noticed that after turning any hot water tap on, the flow would begin to warm (warm at best, ***** ***** hot) for about 30 seconds then ramp back down to cold, then start to get warm. Rinse and repeat over and over. The same thing happens when CH demand is introduced by turning the room stat.
I've had the front cover off and one-by-one disconnected and reconnected each spade connector a couple of times to eliminate any dry connections - no change in behaviour. I then took the combustion chamber front cover off; the spark gap is set to 4mm as in the installation manual and what I assume is a flame sensor (thermocouple?) is hovering over and in-line with one of the burner bars. Again, all connectors tight and secure. While it was open, I also carefully hoovered any detritus and dust from all surfaces in there without knocking or disturbing anything.
When either the DHW or CH demand first starts the boiler to life, the fan fires up and doesn't sound out of the ordinary, then the quiet rapid clicking of what I assume to be the ignitor sparking, then the flame burns. The flame burns for about 3-4 seconds and then a second firing of the ignitor, even though the flame is still burning. A few seconds later, a slight click (of a relay?) and the flame is cut off. The fan still appears to be running for 20-30 seconds or so, then the whole process starts again. The only difference in visible behaviour between the DHW and CH starting is that the CH lights the 30 deg C red indicator light which goes out just after the flame being cut off. The LED is static and not flashing like a fault condition would.
At no stage do any red fault indication LEDS come on, apart from the green "on/ready" one. Altering the Winter/Summer mode knob to CH/DHW or just DHW makes no difference.
I'm an IT security consultant by trade so no expert in the finer details of what would cause this, but my inexpert guess would perhaps point to the flame sensor over the burner bar no providing enough voltage drop/gain to signal a working flame to the PCB. I've got a multimeter so can potentially check any continuity, resistance or voltages from sensors, given direction as to where to stick the two meter probes.
I think I've covered everything I've tried and tried to give as complete a picture as possible of all the symptoms. Hope you can help me out, Sean.
Submitted: 1 year ago.
Category: Plumbing
Customer: replied 1 year ago.
Anyone? It's been over 24 hours since I asked this and no response.Here is the a video of the boiler in operation.https://youtu.be/_NesSQzFAxE
Expert:  Andrew Smith replied 1 year ago.
It sounds like it has an ignition problem, it lights then it goes out.
If it failed to light altogether then you would get a red light.
Try cleaning the electrodes with scotchbrite until shiny, if that does not work then replace the ignition electrode and lead