my hot water cylinder is leaking badly and current potterton boiler is on last legs i'm told. we live in a tall, narrow (4 story) 3 br/3bath house, and water cylinder and boiler are in cabinet together on 1st flr, and there's a cold water tank on the top floor. there are pumps on 2 upper flr bathrooms. i am getting all sorts of conflicting advice - that we shld get a megaflow; just replace the cylinder; or that we shld replace heater and boiler w. combi. at this point was thinking of getting a combination boiler and a pump to get the water to top floor, i've been told worcester is one of the most reliable brands. any advice appreciated