yes there are bypass valves. On the 24.1 they are accessed by removing the cold air return vent or by removing the base of the passenger side bed.
I'm not sure how you access them on the 25.1. Looking at the pictures of the 25.1 on the Thor website I would guess its the same for that model (remove cold air return vent).
This is what it looks like behind our cold air return vent:
If you look behind all the stuff (at the top of the hole you can see the white styrofoam insulation of our water heater) you'll find the 3 bypass valves.
(Note: The black box is the auto-switch for when the genny is running. I have since secured it to something a bit more permanent than just hanging by the 120V wires....Thor quality at its best!)
Hopefully you didn't run your water heater on 120V yet--you'll burn out the heating element with no water in it.