Ideal minimiser SE boiler fault - advice please

[glider26]

Hi, I have a Minimiser SE boiler. Lately it sometimes lights up for 2 seconds then goes out again, leaving "lock-out" LED 2 on the PCB lit. When this happens, it is always when the boiler has been off for hours, such as when it attemps to light up in the morning after having been off during the night. I can usually get it started again by rotating the boiler's thermostat to off and then back to approximately 4 or so a couple of times. After this initial difficulty lighting up, it normally lights up repeatedly without further issues during the day.

I should add that before this started (and I don't know if there's a causal link), the condensate pipe which runs outside froze which caused a leak from the boiler. I've since isolated the pipe and in any case temperatures have been above freezing. There's been no more leaking. I don't think the PCB was leaked onto.

I understand from the fault finding diagrams in the manual that there could be an issue with the flame detection lead but was wondering whether someone could offer further advice, especially in light of the fact that this fault only occurs during a "cold" start-up.

 

[45yearsagasman]

Correct servicing of these boilers is critical to reliability. There have been many updates to this boiler, burner, electrodes, gas valve, condensate trap and PCB to mention a few. There is no advice to give other than to get it looked at by a pro.
The flame detection lead is the last thing I would be looking at.

 

[glider26]

Thanks for that, but in the meantime do you (or anyone else) have an idea as to why this only happens on early morning starts and not on subsequent boiler starts?

 

[45yearsagasman]

More than likely the fault will be inside the heat exchanger combustion chamber, but it could be many things, including a gas supply fault. Please don't attempt to do this yourself. These boilers are now ageing and my honest advice is not to spend excessive amounts on it.

 

[Boilerman2]

As per 45year's post - these are an early pre-mix type burner which have to be set by someone who really knows about Combustion

The reason it seems to fail first start - is simple Just like your car, the Cold start is the one likely to fail!! time for a pro

but buget for a new boiler soon!

 

[Agile]

I very rarely see any of these any more.

If not serviced regularly like every 6 months then dirt inside tends to block up the condensate areas.

Apart from that they are surprisingly reliable for an Ideal boiler.

Get a professional!

Tony

 

[glider26]

Thanks for the info and the advice. Even though I regard myself as fairly competent in terms of DIY (esp with a manual on hand!), I wouldn't dream of removing the burner of this boiler myself to adjust the flame detector and the spark electrodes. I've scheduled a service for the boiler. I hope a standard service includes removing the fan + burner to adjust the probes and electrodes. Is that correct? Thanks.

 

[45yearsagasman]

The fan and burner should always be removed, but as for adjusting the electrodes, it sometimes will buy you a bit of time, depending on condition.
Heat exch should be thoroughly cleaned as well.

 

[Agile]

I would always check and if needed adjust the electrodes.

As for removing the burner I would come to a decision after checking the combustion parameters.

On that model they accumulate so much Ali hydroxides that I pay special attention to cleaning that knowing its such a common failure point.

Tony

 

[nickso]

I would always check and if needed adjust the electrodes.

As for removing the burner I would come to a decision after checking the combustion parameters.

You can only adjust the electrodes after removing the burner.

 

[ollski]

Thanks for that, but in the meantime do you (or anyone else) have an idea as to why this only happens on early morning starts and not on subsequent boiler starts?

Because the alu oxide deposits get damp overnight and the ignition spark tracks through it causing ignition failure.

 

[glider26]

Thanks Oliski. In my case though the burner does light briefly (burner light on and little bellow of smoke for 2 secs) before extinguishing. Is that still compatible with your assessment of oxides spoiling the electrodes? What about flame detection rather? Can that probe also get covered in oxides?

 

[ollski]

Well the reason the minimiser baffles out is because the fins are chock full of the oxide so the gas / air ratio is unable to support combustion as it can't breath, that can cause explosive ignition which damages electrodes and seals. Perhaps you have a combination of problems?. It's not unusual to have to service these things twice a year because if the build up solidifies on the heat exchanger fins it can build up to be impossible to remove.

 

[nickso]

Another well known fault is condensation in the gas valve diaphragm/tubes. Causes the same fault but it's usually more terminal for the gas valve. You can usually get the boiler to light by sucking on the sense tube that sticks out of the boiler case at bottom right.

Burner pressure also gets pretty sensitive on these after they get choked up, too low and it burns worse than they do normally, too high and it burns better but tends to be a bitch to light.

Just replace it

 

[Boilerman2]

I thought Ideal did a modification for the water in the sense tube fault?
I remember converting around 150 of them on a housing estate years ago for Ideal (Kerching!!)