Our system is even worse with a Red Dot heater in the cabin. What I have found is that until the hoses are full I do not get circulation through the high spots which in our case is the water heater. The way I check to see if the hoses are getting hot once the engine is warm. It takes a few cycles to get there. I have thought about making a filler device which would be a funnel welded to a pressure cap. It would give some extra coolant volume to take the place of the air that burps out of the system. With the current configuration it takes several heating and cooling cycles to bring the coolant in from the expansion tank.