I have done a search on "no Hot Water" here on RV.Net and one of the threads talks about a one-way valve either on the inlet or outlet side of the water heater that may have failed or is plugged. I don't know if I have one of those or on which side but that causes me to think changing the valve to bypass the water heater might give me some results that might lead me in the right direction. Any Montana 3400RL owners know if I have a one-way valve and whether it is on the inlet or outlet side of the water heater?