sandpirate
Member
OK, when you pressurize that area and air is leaking to the out side, where do you get air to make up what you have blown out side?? It has to come from somewhere. Lets say your living area is air tight, you would create a vacuum in the living area, once the furnace shuts down, you would suck cold air in any hole you would leak air out of until your inside would equalize with the outside. Once you build up the pressure in an area and equals the output of the source of the pressure, you will not get any more air in there than what leaks out any holes. You will have the area pressurized before you get any heat since the blower will start circulating air before it gets warm. Your output of the blower is greater than any leak you may have or not, you would get very little warm air in that area before the thermostat in the living area is satisfied and shuts down the furnace.
In these rv's we are concerned about keeping the heat in the conditioned space since we aren't dealing with a 6500cfm motor in these furnaces. A little positive pressure inside will not create this backlash of cold air being sucked back into the coach if it's properly sealed from the outside air; as a matter of fact it will do just the opposite. Either way, I'm not going to pay to heat an uninsulated trailer underbelly that is only being protected by plastic sheeting that is no thicker than a cheap cardboard box.