[SV650rules]

Our Vaillant condensing boiler was installed in 1996, has stainless steel heat exchanger and is still going strong. It is on its third fan but only because flue was installed wrong.. They fitted it with flue pipe sloping back towards boiler, which meant condensed flue gasses ran back down flue pipe and dripped onto top of heat exchanger casing and filled the chamber where the fan was with acidic steam. Basically the first couple of fans lasted about 4 years each because the unsealed ball bearings rusted away, once I had spotted the wrong flue slope and sloped it away from boiler the 3rd fan still going strong.