Homer --- I did exactly what you are talking about --- I put a "jumper line between the hot output line and the cold input line. It has a valve on it that stays closed when not winterizing. When winterizing, I open that valve and shut the two that I put in the cold and hot water lines after and before where the jumper line leaves the cold and hot water lines respectively. Hope that makes sense --- now I have zero problems that were caused by the check valves. My understanding was that the check valves were needed only for the winterization process only anyway.
Dave and Karen -- '02 Ultimate Advantage 36 C, 350 HP Cummins, Allison 3060 Tranny
'13 Ford Edge, InvisiBrake