Baxi 105e - gas lights up then goes out after approx 1 sec

ANDPOOH · 23 Nov 2006

Boiler out of action now for two days and its cold!!
I've checked the pressure switch which is Ok, The electrode is sparking ok and there is gas flow - but that just stops as if there is a safety circuit cutting in.
The baxi manual does not list this fault - doh.
My local engineer has been out & replaced the pcb as he said it's always the fault - but fault is still there and he's scratching his head (as I put another layer of clothes on!)
Could it be a faulty card?
help please

cross thread · 23 Nov 2006

could be faulty low gas setting for ignition

kevplumb · 23 Nov 2006

ANDPOOH · 24 Nov 2006

Gordongas, How do I check this??
Kevplumb - what is aps??

kevplumb · 24 Nov 2006

gas setting you don't

APS= Air Pressure Switch

Paul Barker · 24 Nov 2006

As Gordon says get low gas rate checked, it would be strange for the aps to give permission to light and then remove permition always at the same time. You would expect more eratic performance. It is normal however for failure to detect a flame to lock most boilers out after 5 seconds, but it is the most likely scenario. Whether it is the electrode gap, sense leed, connections, polarity low gas rate has to be checked out. If non of the above, may well be another dodgy board, but Gazthepottyengineer would be more likely to get it right than me.

Baxi-Remeha · 24 Nov 2006

get them to check the electrode is in the flame as well.

pannierstan · 24 Nov 2006

Have you checked polarity. I had one of these which was traced to reverse polarity which had worked!! then decided not to.

If its lighting up which light flashes. Is it the flame lockout or what??

ANDPOOH · 1 Dec 2006

Thanks guys for all your suggestions, boiler man came and replaced the PCB card for a second time and the fault was still there!!!
Don't know if I found an 'iffy' boiler service engineer but he did not know what to do next.
I read the manual and tried the water to see if it had the same fault (as this circuit bypasses the coil) hey presto the flame stayed on and we have hot water!!
Looks very likely that the fault is the coil on the gas valve so we are getting that checked out now (BUT at least I have hot water)

Interestingly having spoken to another service engineer over 30 baxi boilers have failed 'electrically' within a week!!. this has been traced to a power spike in energy supply. Good old baxi boilers

You guessed it I'm buying a power stabilizer for the boiler just in case.....

fitz1 · 1 Dec 2006

check your earths and neutrals.

Paul Barker · 2 Dec 2006

All boilers modulate hot water, so you must have to run tap very fast or boiler will cut out anyway.

Are you sure you've nailed the fault?

pannierstan · 2 Dec 2006

Paul Barker said:
All boilers modulate hot water, so you must have to run tap very fast or boiler will cut out anyway.

Are you sure you've nailed the fault?

Something tells me he will be back Paul

timmy74 · 2 Dec 2006

ive had this fault many times with the ch lighting on low flame then knocking off, dhw usually works ok when this fault occuring

Paul Barker · 2 Dec 2006

So was it low burner pressure needed adjusting?

ANDPOOH · 3 Dec 2006

Ah those of little faith!,

Removed front adjuster screw from the coil (once I had marked it and counted screw turns to remove)
The screw is plastic and had a molding tag at its end (which looked well and truly squashed) - removed this tag and refitted back to original position (did not work)
Wound in 1/4 turn per test - 3/4 of a turn later the burner stayed on!

Discovered this is what adjusts the burn pressure so got the boiler man to calibrate back within guidelines - though could not achieve greater than 10.5mBar (cold night).

So yes Paul the low burner pressure needed adjusting.
I did get my colleagues at work to check my original PCB -diagnosis was its f@*ked 3 relays blown.
All's well that ends well!!

Cheers Guys

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Baxi 105e - gas lights up then goes out after approx 1 sec

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