My parents in laws boiler has been condemmed as the flue is loose, the boiler is 20years old and it was pumping out carbon monoxide. British Gas quoted £7000 for a new boiler and to fix a new flue. Its an old part thatched cottage so the walls are quite thick and the flue goes up 10 feet or so above single storey kitchen extension. However £7000 seems extortionate, and a quick search shows a couple of sites that are not complimentary to BG. Anyone with any experience of BG boiler replacement?