Like Red T, I created a little more air circulation by cutting the flange on the W/H door at the bottom to allow for more air to enter. I also hooked up a small fan (computer DC fan) inside of the W/H to create a little more air circulation. The fan only comes on when the heater is operating on propane -- you can "rob" some 12 volt power from one of the wires that becomes "hot" when the propane starts up. The fan will not go on when using AC or DC power to heat the water.
Dave and Karen -- '02 Ultimate Advantage 36 C, 350 HP Cummins, Allison 3060 Tranny
'13 Ford Edge, InvisiBrake