Potterton Promax ignition fault - please help

Hi, Would really appreciate some help on this.

I have a Potterton Promax 15HE - estimate 5 years old. A few months ago it developed a fault where it will not always ignite - this seems to be intermittent but will normally always fire when completely cold.

Typical day - I have the boiler on in the morning for about an hour - it then goes off on the timer - no problems. It will then come on in the evening at say 5pm - again no problem. It is programmed to stay on until 10pm, but somewhere around 9pm 'something' happens and it shuts down effectively going into ignition lockout - or similar. I say this because if I don't turn it off and on again before going to bed, it will not come on the following morning. If I do turn it off and on again before bed it will come on in the morning - and so on! So basically every night I have to re-boot it or it stops working.

Having read other posts I have so far replaced the combustion box door seals and both probes - to no avail. The burner plate does have a small crack in it on the side of the casing but I can't really see how this can cause the problem? Or can it? The burner did have some debris on it but I have hoovered this off. Flame is quite orange when alight - should it be really blue on this model?

Can't really be the ignition pcb surely as it sometimes works - and this would not cause the shutting down symptom. Oh yes also it does seem to have quite an explosive ignition.....

As I say above - HELP!!

From my experience, a split in the side of the burner usually leads to explosive ignition/ignition lockout, distortion of the electrodes, and burns out the combustion chamber seal which can also cause lockout due to the o/heat stat on the fan.

Potterton have replaced the old style burner which has a kind of 'fabric' top, with a new 'ceramic' topped burner. A new gas pipe usualy comes supplied to

Change the ignition pcb. That will cause the faults you describe. Actually, most components on the Promax will cause that problem

nicknox said:

Change the ignition pcb. That will cause the faults you describe. Actually, most components on the Promax will cause that problem

Click to expand...

nicknox, but surely the ignition pcb is concerned only with igntion? Why would a fault on this board cause the boiler to shut-down/lockout after a few hours running?

aaronH - Thanks, but being that I've got a new door seal, how would this cause it to shut down?

OK - A theory, Could it possibly be the CH pump? I say this because lately it has become a bit whiny. It was set to speed 3 (highest setting). If I reduce it to speed 2, it becomes much quieter (so I've left it there), but does seem to make the boiler firing problem worse. If say the pump is on the way out and not pumping enthusiastically, could insufficient water flow cause the bolier not to fire? Could it also cause the bolier shutdown after a few hours by effectively causing it to overheat as the water is not passing through it quickly enough? Rads do seem super hot lately too....

Does this theory work?

The ignition circuit not only provides the spark to ignite the gas but it provides the timings of the combustion related aspects of the boiler and it monitors the combustion process.

Although you do have some idea of what you are doing, I still think that its inappropriate on a public forum for anyone to be giving you advice that will encourage you to do gas related work which, for safety reasons, should only be done by a competent CORGI engineer.

Tony

Agile,

Sound advice of course, and I should point out that I am not looking to undertake any 'gas' work myself - I am looking for a range of opinions so that I can pin down the most likely fault and if necessary get a Corgi Engineer to replace. I don't want to pay someone to keep replacing things on a trial and error basis and possibly end up spending £600 - I would rather buy a new boiler.

If it was possible that it could be the pump for example, this would cost me £50 and I could do myself without a problem.

Thanks for the info re the ignition pcb.

Thanks

Cat-Kicker said:

I have so far replaced the combustion box door seals and both probes - to no avail. The burner plate does have a small crack in it on the side of the casing but I can't really see how this can cause the problem? Or can it? The burner did have some debris on it but I have hoovered this off. Flame is quite orange when alight - should it be really blue on this model?

Click to expand...

Those are things which should be done by a CORGI.

An orange flame is an indication of incomplete combustion when CO is being produced. Thats a serious sign of a possibly dangerous situation but you did not seem aware of that!

There is no chance of a £600 bill! You could use the fixed price repairs by BG or Potty which are around £200.

You should never employ anyone who is going to change parts at your cost.

You should get someone who is going to diagnose the fault and fix it.

Having said that random lockout faults on your model are tricky to pin down as they can be caused by the PCB, gas valve or any of the smaller parts. Thats why the fixed price repair is such good value in your case.

Tony

Tony,

To clarify - when I say 'I have' I meant that I have paid for it to be done. I had a CORGI Engineer do a service, and he replaced those parts, he was also the one to advise re the cracked burner (which he showed me and we hoovered off dust etc). He does not however, offer a fixed price repair - hence the potential bill.

I am aware of what the orange flame could mean, however CORGI man did not seem concerned (another reason why I've not rushed to call him back) and that's why I am seeking opinions on this board. As I said above, I will undertake any 'plumbing' work (as a competent DIYer, and professional Mechanical Engineer) but I would not and never have undertaken gas work of any kind. Still - you are right to point out the potential dangers.

Please could you give me some more info re the fixed price repair thing from Potterton? I've not heard of this. Does this price mean they will visit as many times as needed until the problem is resolved? Sounds like it would be a good option.

Thanks.

I work for Baxi (heateam). You can get a fixed price repair for 269 (boiler guaranteed for 1 yr all parts)...or go get a d&g insurance policy.

Agile is right, these are tricky beasts to track intermitent faults. Check your condense trap and pipe work are clear, flame retification lead terminates onto top.....any water contact will cause earthing and flame failure.....don't rule out O/H on fan even with new seals, a door change is better than seals

Did this problem ever get solved? I am experiencing the exact same on mine.

Whether it did or not is unknown - previous discussion from 9 years ago.
Gas repair advice is not permitted on this forum.