I am getting quotes to replace the central heating in my house and so far these have all been for a combi boiler. My FIL was up at the weekend (he's a builder) and he reckons that unless space is a issue we should replace the old system with a new conventional boiler (i.e. keeping a tank). Space isn't really an issue as the tank is tucked away in an airing cupboard so is there any benefit to having a conventional sysyem rather than a combi? Broadly speaking which would be cheaper to install?