Just a side note: It's not uncommon for the hot water bypass valve and associated one way check valves to hold residual water and crack during winter storage. Some of the hot water lines are by passed when engaging the by pass valve and draining the hot water tank. The by pass valve keeps the anti freeze from entering the hot water tank and leaving a residue in the gunk in the bottom of the hot water tank (never ending bad flavor). When using the bypass valve the pink anti freeze never reaches these lines and several check valves associated with this line.
The work around when winterizing is to: 1st drain all the lines and hot water tank completely and then re insert the tank plug. Then use 15 - 20 lbs of pressurized air inserted through your by pass induction line. This will blow that residual water out of all the water lines, including the hot water lines and all the check valves. Then throw the by pass valve and insert the non toxic anti freeze into the system.
Learned this the hard way many years ago
2014 31SL, 5.5 Onan, Custom Magnum MS 2812 Inv./Chg.+ bat. mgmt. system, 2 Lifeline Grp. 4 agm bat.(420 ah), MorRyde Basement Slider, 2013 F-350 D. SRW.