Mu mum's Keston Celsius installed December 2003 was running fine, then a brown burnt patch appeared on the front casing over the weekend. Called out Keston specialist who diagnosed a failed heat exchanger, cost to replace including P&L about £900 !!! Not surprisingly he agreed that replacement would make more sense at this price.
There is a five year guarantee on the HE but unfortunately the service history is lacking: each year it was serviced under the Keston summer service scheme but last year they didn't offer it, and so the service was missed. With downfiring boilers like this I 've always tended to the view that if running well there's nothing much to be lost by leaving well alone - expensive mistake. Given that even if a warranty claim were accepted they only supply the HE, and the labour has to be paid for, it would still be several hundred pounds for a boiler whose reliability can be patchy and which has hopeless parts availability (IME anyway).
So having discussed it with my mum and given that I won't be on her doorstep much longer, we decided it made more sense to bite the bullet and get her local friendly (they are good) plumbing and heating firm to replace it, since she will have to rely on them for all repair and maintenance once I move. When she spoke to them and said it was a Keston the response was "we refuse to touch them": their preference is for Glow-worm. I'm saying nothing: I'm sort of being blamed for choosing this one!
Once again leading edge turns to bleeding edge. A Keston Qudos would be a straight swap - lot of flue needed for anything else - but sadly for Keston you don't get second chances.