If you have a cylinder and header tanks, just buy a system boiler rather than a combi. Depending on local building and planning regs, you may have to get a high efficiency condensing boiler. Otherwise a standard type is ok if you don't have to submit details to the council. They will do all they can to get you to spend more money! Don't forget that you will need to seek assistance from a CORGI registered gas fitter when you replace it. You should be looking around £350-400 for a standard boiler, and around £550+ for fully condensing. Search on ebay.co.uk or screwfix.com for some guide prices.
sparkyfixit@westways-multiskill.co.uk
January 2007