I'm a bathroom fitter and have a query about cold water tanks remaining in use when a combi boiler has been fitted. Often I find that bathroom cold supplies are still being fed by the cold tank in the roof rather than cold mains. Is this because regs say that you should have a cold tank or is it laziness on the part of the chap who installed the combi? I often have the option of chopping out the old cold feeds from the roof and running cold supplies to bathroom services in mains cold. Any reasons why I shouldn't do this? Cheers.