Pat, did that when we had our extension 2 years back. Well worth it. As you say, no shower pump, no tank. Combi works a treat. Got a wireless thermo we move round to where we are in the house and it's great too thinking of changing it to one I can control on the phone/tablet once I get round to sorting the new alarm/cameras/lights (my thinking is a central control for everything when I'm out of the house)