I have a 2008 Fleetwood Tioga 31M. Under the kitchen sink, there is a small lever to the right that says it is for "bypass." I don't know what it is for. Can a Tioga owner can tell me? Thx.
A way to check is to put it to bypass and the open the water heater drain. Turn off the water heater and depressurize the water system 1st (water pump off).
After the tank is drained, pressurize the water system. If water comes out of the water heater, then the bypass is for something else.
Then open the bypass & see if water comes out of the water heater. That will confirm it's function.