Taking out , bbu, fire, cylinder, tanks all rads and pipework Install combi on outside wall Upgrade 14 m of gas pipework 8 rad heating system Replace 20m of hot pipework What an Interesting thread this has turned out to be , its opened my eyes . So most of you are saying this is do-able in a 5 ish day week . One man on his own is going to do that lot above . carefully move furniture, remove carpets , pull up floorboards , notch joists , install rads and pipework (copper), pressure test and flush pipework ( maybe) . Install boiler , filter , coni pipe , new gas pipe, seal flue , commission system and boiler , explain how it works , everything replaced properly and leave nothing undone, etc etc 100% finished . Oh and answer phone god knows how many times . In a week ????