Replacement of vented cylinder to unvented

you can buy a pressure gauge which will fit onto an outside tap if you have one this will show the pressure, 2bar minimum, you will need to do a flow rate test aswell you can do this at the outside tap again.. get a standard size 20 litre bucket. and time how long it takes to fill it.. if it fills up within 1 minute then you know your water main can achieve the demand for an unvented system.. do all this at 8am in the morning which is peak demand for all water mains. also better add that the 2bar minimum is what is suggest as minimum for a standard 2 storey house.. if you have a 3 or 4 storey then id suggest 2.5 bar pressure absolute munimum.. regards to pipework.. depending where you intend on siting the cylinder youl need to get all water services to it.. including *water main into the house *cold water pipe serving the house *hot water pipe serving the house *heating flow and returns from boiler *waste pipe *secondary return if you have one a fair bit of work really.. you shouldnt need to replace pipework in floors or walls.. might have to replace some old taps or a toilet float valve if they wernt designed for water mains.. you can keep the old boiler but the heating might need to stay vented unless you either replace boiler for a systems type or maybe your old boiler is suitable for pressurised aswell.. hope this gives an idea.. good luck toby@tservices