As part of a kitchen upgrade, we are considering upgrading our central heating system. We are aware of some of the problems of combi-boilers but would welcome the increased space and lower heating bills. We live in a large, old maisonette so have quite a lot of bedrooms to heat and 2 bathrooms. Would a large combi boiler such as Worcester Highflow 400 cut the mustard and would we have to get all the plumbing in the flat re-done to allow for the higher water pressures ?