I wrapped the hot side of the water hoses to the heater, with hose insulation that you can get at any hardware store, This keeps the water hotter as the cold air can't cool it down before the water gets to the heater. I also sealed the top and sides on the heater so cold air doesn't go around the heater and into the cab, but has to go through the heater. There are area's on both sides in the fender wells that can be sealed up as well. I used dense foam and cut it larger than I needed installed it and let it expand to seal it'self in place. The foam gets wet but doesn't seem to affect it any, it dries out when I'm done. When it gets colder and it's just snow it should work even better.