Vaillant sometimes doesn't ignite

[Matt Durkin]

Hi All, I have a vaillant TURBOmax Plus boiler which runs the heating and hot water. Occassionally the boiler doesn't ignite (electronic ignition). It tends to be oer common if the boile hasn't been used for a while (i.e. in summer when heating not in use). The auto ignition is definitely working (I can hear it clicking) but the flame doesn't light. Now strangely, the problem seems to have completely dissapeared in the last 6 months, but prior to that it was getting quite bad, with the boiler locking itself off for safety reasons. It would rty to light for about 30 seconds, then lock off.

Does anyone know what can cause this to happen, and if I need to have the boiler services? Vaillant would offer no advice over the phone other than to arrange a £90 visit by an engineer...

Thanks, Matthew

[StealthUK]

Check your service manual first - it will contain flowcharts to troubleshoot.

[Matt Durkin]

P.S. I ought oto add that the manual doesn't offer a solution to intermittent lighting.

[raden]

In message , Matt Durkin writes

A sticking gas valve ?

[Ed Sirett]

I'd put that to the bottom of the list. After checking the ignition electrodes are free of debris and in the right place, the HT gets to them and not elsewhere. Then I'd go for checking the ignition rate (lowest) burner pressure. These can and do drift and have a fairly sensitive effect on the ignition sucess of this model.

Also amazingly a slightly dodgy APS can have weird effects on this model.

Don't be surprised if on opening the combustion box the boiler starts behaving! You adjust the gas pressure it stop lighting, you close the box it then works OK!

[raden]

Not if he said that it happens after it's been left for a while