Dont do much installation work but usually fit worcester greenstar 30si. Have a new installation to do rip out old and fit new. The house is a 3 bedroom semi and is getting extended downstairs, extra room and kitchen enlarging and shower room downstairs. So the boiler will providing heat for 10 rads and dhw for bathroom basin and bath and downstairs mixer shower and basin also kitchen sink.30si would be ok for heating but not for hot water.Any suggestions for a combi boiler to suit this installation. p.s. cold mains pressure is ok.