Boiler Flame Failure Lockout. (Fed Up!!)

Snorbitz

I'm at my wits end! I have a five year old Potterton Performa ECO HE condensing boiler. I'm getting this dreadful constant intermittent red light and amber light both flashing. Red light means 'Flame Failure' and amber light means 'Burner On'.

This means no central heating or DHW. It has a will of it's own. Sometimes it fires up for a few seconds then the lockout kicks in (flashing lights), and the boiler goes dead and refuses to reset. It cycles like this. It just won't stay on long enough to heat the house. Tried the Reset knob but still nothing. Sometimes, it won't even reset, as I select reset, the lights are still flashing! If I turn the boiler off for a few hours then try again, it might work again for while then lockout process starts all over. This is crazy!

Fault Finding.

We've had the APS (Air Pressure Switch) replaced, the PCB, the overheat Flue thermostat and another heat safety stat. Checked and cleaned the spark electrodes. Flue not blocked. Gas safety pressure fine. Still the same. Engineer has got the trusty multimeter out and done various continuity checks. he's at a loss. He says there's not much else left to check.

Anybody else experienced similar and found a solution?

alleycat`

On the face of it that sounds like chucking parts at a problem and not "fault diagnosis".

Does anything in this (section 4) sound like you:-

http://www.potterton.co.uk/docs/5111812-08_operating.pdf

The speed of the "flashes" mean specific things skimming the manual.

As you've not said how often each light is flashing i can't suggest which point to start with.

HTH

Snorbitz

alleycat` wrote: »

On the face of it that sounds like chucking parts at a problem and not "fault diagnosis".

Does anything in this (section 4) sound like you:-

The speed of the "flashes" mean specific things skimming the manual.

As you've not said how often each light is flashing i can't suggest which point to start with.

HTH

There is only one section that shows the two flashing lights to which I refer to above in my post. Red, (Flame failure) and Amber Burner On. This indicates a problem with the overheat stat. This has been replaced, as I explained above.

Fault diagnosis has been carried out as explained above. It'a a process of illumination now. I work for a large chain of plumbers merchants so I get staff discount on all my boiler parts. I get them, the engineer fits them. We are not chucking parts at it. This happened once before (Same Symptoms), only it was the APS and PCB that were the culprits. So the manual at that time was not helpful. It was not the overheat stat at that time. This time, it's all crazy!

On my make of boiler, ignition lockout can also be caused by a wire connection that comes from a pin on the PCB into the condensate trap. If it gets damp, it creates a low voltage causing lockout because the wire is joined to the same pin terminal as the flame sensor. So again, manual wouldn't of been right on that scenario either.

Regards.

alleycat`

I'm probably misunderstanding what you've typed but the manual appears to suggest the "frequency" of the light flashes indicate different things.

1 second flashes and 2 second flashes are specifically mentioned.

I refer to:- "lockout kicks in (flashing lights)"

I wasn't sure if one or both lights were flashing and at what interval hence there are 5 distinct possibles in section 4.

If you've worked out those flashing lights are for the temp sensor then fine and dandy. It didn't come across as that was "known".

It also doesn't mean the "replacement" sensor or the cabling to it isn't defective.

I'd have tried a second sensor, you may already have done so, to see if that resolves the issue.

I seem to recall the one i replaced on our old baxi cost less than £1.

Other things i'd look at:-

Has the condensate drain and flue been checked for partial blockages? (not mentioned)

Is the boiler holding pressure? (not mentioned).

Has the gas solenoid been checked to make sure it's not failing?

An outside possibility is that the solenoid on the gas regulator is on the way out it might "stick" or "de-energise".

I'd assume as you work for the merchants you could test some of this with a minimal re-stocking fee if they are carried?

Snorbitz

Yes, it's both red and amber lights flashing every two seconds. The green one being the power light which stays on. The boiler pressure is holding fine. Condensate pipe which runs inside the loft, (where the boiler is - I live in a bungalow), and out through into a drain pipe down the outside is not blocked and no birds nests in the flue. Gas valve has been checked.

So perhaps you can see now what I mean. There's really not that much left to check and is really baffling. I'll mention to the engineer about the solenoid and see what he says about that. This Potterton has literally,..'gone Potty'.

Thanks for your reply by the way.

malc_b

Maybe relevant. I have a oil boiler that was playing up and locking out with flame failure. It was very intermittent. In the end it turned out to be the spark transformer. After I replaced that it was obvious it was at fault. Before the boiler would light, sometimes, usually every time I looked at it. Failures happened on dark, wet nights when they were the biggest pain (access was from outside!). You could hear the boiler fire up and it all sounded ok (when it worked). However, once the transformer was replaced if you listened you could hear the sparks buzzing just before the firing. With the new transformer you could hear a real buzz a second or so before the firing. With old this was inaudible so the spark was a lot weaker. Hence the intermittent failures which resulted in lockouts.

So can hear the spark before it fires? Oil won't be that different to gas in firing sequence I would have though? If not then I would be tempted to look at the transformer.

Snorbitz

malc_b wrote: »

So can hear the spark before it fires? Oil won't be that different to gas in firing sequence I would have though? If not then I would be tempted to look at the transformer.

The only transformer I know of is on the PCB in my condenser boiler but the PCB has been replaced. Or are you meaning something else?

Snorbitz

alleycat` wrote: »

I'd have tried a second sensor, you may already have done so, to see if that resolves the issue.

I seem to recall the one i replaced on our old baxi cost less than £1.

Well would you believe it? I took your advice and tried a second temperature sensor and that fixed the issue. These sensors are tiny little things but when they go faulty, they can bring a boiler to it's knees.

alleycat`

Snorbitz wrote: »

Well would you believe it? I took your advice and tried a second temperature sensor and that fixed the issue. These sensors are tiny little things but when they go faulty, they can bring a boiler to it's knees.

Glad it sorted it for you.
Been on the wrong end of a dodgy replacement part myself before.
On the positive side i guess you now have some spares with regards to the other bits you replaced.

SaveMyMoney_3

That's good news - who'd of thought it would be something so simple!