GDS-3950BH wrote:
"Special provisions must be made in mobile homes to introduce outside air into the dryer. The opening (such as a nearby window) should be twice as large as the dryer exhaust opening."
Direct from the manufacturers legal department. Some idiot apparently asphyxiated themselves using a gas dryer in a mobile home. That seems like something one would really have to work at but you have no shortage of morons out there. Mobile homes I have ever been familiar with were far from an energy efficient, draft free, airtight box with no air infiltration.
Your RV furnace has similar specifications. There is a minimum square inch requirement for both the output ducting and the grate to let air into the cabinet. Air must move for these things to operate.