You turn both valves to OFF. Otherwise, if you turn the bottom valve off, leave the top valve on, you'll bypass filling the water heater at the bottom, but will flow water into the top, filling it anyway. Same would happen if you switch and turn the top valve off and leave the bottom valve on.
They work in "unison" so both on (summer use) or both off (winterization)...
__________________
John
2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS
|