My Vaillant Boiler Not firing Up

[Mo Murphy]

Guys,
I have a problem with my own boiler and I wondered if any of you chaps could point me in the right direction ?
When the boiler is called for it tries to light but the burner lock out light comes on and the burner won't fire. It will light however if the switch is turned to manual light.
I thought it might be the igniter but since it works on manual lighting it obviously isn't.
Any thoughts, oh learned ones ?

Cheers
Mo

[Mike Jackson]

More information required. Watch the ignition sequence and see what happens and at what point in the sequence it fails. Generally the sequence will run something like fan runs, ignition spark commences, gas valve opens to pilot or low, pilot/burner lights, flame sensing device detects flame and allows burner to light and full pressure.

Once you know where in the sequence the failure is you should be able to locate the faulty component with the aid of the manufacturers instructions.

Mike

[Mo Murphy]

Thanks for your reply Mike. I've watched the sequence as you suggested.

The fan comes on (I can hear it and the light confirms ok), the ignition sequence is initiated (confirmed by the light) but the burner fails to light and so the lock out comes in after 10 seconds.

Looking in through the small glass window I can see that when the burner fails to light there is no ignition spark. When the burner lights there is an ignition spark. So therein lies the problem Marvellous thing, logic

My next question is - From your experience, would it be likely to be the ignition electrodes faulty or the transformer on the main switchboard ?

Cheers
Mo

[Mike Jackson]

You can generally hear the spark arcing somewhere else if the electrodes or leads are faulty. It's common for the electrode leads to pinhole where they pass through the case. If this is the case you'll hear it arcing across to the case.

If there is no sound it could be the spark generator but ideally you need to check with the manufacturers fault finding guide as this could also be a pcb fault.

Mike

[Mo Murphy]

Just to update I fixed the problem by removing the connectors to the igniter, gave it them a clean up, reassembled and voila, job done

Mo