Glow Worm 18HXI leaking condensate and CO

Finally had BG out to do the annual service on our boiler which we didn't get last year. We had the check booked in but it was cancelled twice by BG at the last minute due to other demands through the covid situation. The boiler was found to have a problem when it was checked yesterday.

I gather there is a threshold of 10PPM of CO, and the engineer was picking up 12PPM, and a fair bit of corrosion on the brackets holding the main heat exchanger and in the base of the boiler case, so his diagnosis is the plastic flue adapter is leaking. So it is out of action at the moment. We do have a CO alarm near to it and that wasn't picking anything up, but that's possible given the boiler is in our (integral to the house) garage.

I've had a look myself with a tiny USB camera I have, and initial impression was quite bad - i.e. it looks like rampant crusty rot in the areas where the condensate had leaked out, but when I take a little wire brush to it, it cleans back to smooth surface rust. So it looks to me like the condensate has attacked and lifted the galvanised coating on the brackets etc. such that it looks far worse than it actually is. That being said, some of that rust is on the brackets very close to the body of the main heat exchanger and whilst I can't see any clear damage to the rear or seams of the heat exchanger itself, that remains a possibility and I imagine will write the boiler off if that has occurred. The photo below shows the one suspicious looking area on the rear seam near to one of the corroded brackets. I guess the dilemma is whether the CO levels are due to the flue adapter and its leak, or whether it's due to damage to the heat exchanger.


I'm being given the option of the repair being attempted as it's under maintenance (that looks an awkward repair that will involve the main heat exchanger having to come out), OR a few hundred extra discount on a new boiler to offset the repair if they don't attempt it, and further discounts on the mtce to take account of the warranty. The boiler was installed in 2004 and hasn't given any problems till now, but at 17 years old, it is beyond the 10-15 years life expectancy often quoted these days.

So I'm just edging towards replacement right now (whether by BG or someone else) but would value any thoughts.

Thanks.

very common fault on these boilers at 12/15 yrs. it is a fairly quick repair. takes about 1hr but requires the system drain down.

Thanks - worth doing then do you think given its age? My concern is that BG might still condemn it with corrosion up the back of the case.

Just found a YouTube video - I see what you mean!

YorkshireMidge said:

My concern is that BG might still condemn it

Click to expand...

They will, because BG are in the business of selling new boilers and expensive monthly plans to supposedly cover repairs.
Whether it's repairable or not is irrelevant to them.

flameport said:

They will, because BG are in the business of selling new boilers and expensive monthly plans to supposedly cover repairs.
Whether it's repairable or not is irrelevant to them.

Click to expand...

Thanks. To be clear, they aren't saying they won't fix it within the cover we have - there is a slot booked in to attempt the fix on Monday. What they are saying is they don't know what they are going to find when they dig it out - which is a fair enough observation when I can't see with the sort of kit I have either. If it has cracked in the same way as the YouTube video, it looks like water can sit on the plastic ridges behind it which isn't good. So I guess my question is what are the specific reasons to condemn in a case like this?

With the front trim panel removed, the inner front panel has a seal so I assume this is to provide additional protection if anything within starts to leak - as it has. If I'm correct, then IF any area of the case has rotten right through, that would seem to be a very good/genuine reason to condemn it. Ditto if the brackets have rotted through to such an extent where they can't do their job of supporting the heat exchanger. Surface rust alone wouldn't be in my opinion as it shouldn't deteriorate inside the case, but I'm just guessing really.

the back casing is quite thick and it would need to have been leaking for at least a year for it corrode through. i have changed loads with vastly more corrosion and they have been fine

Thanks for getting back to me - I think we might just take a punt on a repair. Because BG missed out the inspection last year, there is a possibility it has been leaking a while so if it does turn up anything genuinely nasty, I'll examine and photograph it myself so I have the option of getting an independent in for a second opinion and possibly the replacement if its really necessary.

Just to close the loop, repair all sorted. It wasn't as bad as it looked. The flue adapter had failed in exactly the same way as the YouTube video - a crack from the stub from when the part was moulded. I notice the new part has been reinforced with a thicker band of plastic.

@snb - thanks again!