the "word on the street" seems to be that the mod con boilers have a short lifespan (15-20 years).
i asked the customer support guy at Lochnivar about their Knight mod con boiler.
he said the exchanger is stainless steel, and requires annual flushing to remove mineral build up, but that other than that, there is no lifespan problem ("it can last as long as you want, if you maintain it").
he also said that flame tips [or something like that] can go, but that they are just replaced.
why do people say that the mod cons have a short lifespan?