Gas boiler not igniting

[Eric The Viking]

Don't get me started on lead free solder (rubbish) and three way valves either! :evil:

The only fault in my CH system is that I'm replacing the three way every couple of years. I really should modify it into two separate valves...

Ours are all two-way valves. They fail often, to the extent that I'll probably replace them all next summer as a precaution. I'm not even sure they all close fully now, but 'on' is better than 'off' in the middle of winter, so I'm leaving well alone until the heating isn't needed in the spring.

It's the motorised valve head that's the main issue. Whoever thought that stalling a synchronous motor for hours at a time against a spring was a good idea should have been strangled at birth (as a pubic service). Why hasn't a sense of shame caused the CH industry to come up with something better in the last thirty years? Yet the manufacturers still bang on about the 'quality' of their products...

 

[mind_the_goat]

and is the kind of bl**dy obvious fault-finding that children should be taught in school (IMHO).

+1

Do you think Gove is monitoring this forum ?

 

[doorframe]

Your boiler has an ignition sequence. If the sequence does not complete it will go to 'lock-out'. This is normally indicated by a red light and requires a reset switch to be pushed/activated. One part of the sequence is confirmation of exhaust airflow by a pressure switch. Just because the fan is running does not mean the airflow switch is satisfied. The contacts inside are a classic fault. Meter the switch contacts (they may be N/O or N/C) and blow or suck on the air pipe supplying it and look for the switch state to change. If you have to blow or suck with any force to get a change then the diaphragm is probably kaput. Another classic cause of insufficient airflow is dust/debris blocking the burner assembly. This can easily restrict the airflow so that there is insufficient pressure to operate the switch. Clean this thoroughly and carefully.

If the problem was no gas supply you would almost certainly still get to the ignition stage (sparking), although the burner would obviously not light.

If it gets as far as lighting the burner the next stage is the ionization probe (like the old T/C). This detects the presence of a flame and allows the boiler to run. No gas or no ignition would cause this stage to fail and the boiler would go to lockout.

You haven't told us the make/model of the boiler.

HTH.

 

[whiskywill]

8. If all the above look OK, it could well be a failure on the control board.

That's exactly what happened to mine a couple of months ago. It must have been poor quality materials and workmanship as the boiler is only 24 years old. :mrgreen: