You want to leave the by-pass on until all traces of RV anti-freeze have been flushed out of your system and the lines are sanitized. Then reverse the by -pass valves and fill the tank.
Flush the H/W tank with fresh water only.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.