[ThePair]

If you start with fully drained lines, and fill the fresh water tank and use the pump, I don't think the hot water tank or lines will fill as long as you keep all the hot taps closed. The air lock within the lines should prevent filling, which is why you have to open all the hot taps prior to turning on the heater, to make sure the air is purged and the tank is full.

My 2 cents...