i have got 3rd floor flat with no gas, the hot water is currently heated by gledhill economy 7 combination cylinder, it sits on a shelf 12inch of the floor, so as you can imagine the flow to taps is terrible, there is a old very noisey pump what helps ,but the landlord wants a differerant set up any idea's, unvented is not suitable as there are problems with discharge, no where for the d2 pipe work to go.