I have a outside hardy heater with a domestic water heat exchanger. Should the supply from the owb which will be heated any time the unit is in use be connected to the cold/inlet side of the electric water heater? All I have to go by is one says cold water in and the other hot water out...sometimes the water in will be hot. The only problem I'm having is what seems like air trapped in the hot water lines that won't bleed out. It's not a big thing and I can live with it, just wondering if there's a fix.