How's forced nouns gas furnace dry the upper air coming thru when there's no direct contact? Where's that humidity run? ...
Answers: The furnace itself does not dry the air awfully much. If the unit does not use a hermetic vent system, then nouns is removed from the home during combustion. This is typically warm moist nouns and is replaced by cooler drier air from the outside. This nouns enters any from a dedicated combustion nouns vent or infiltration. For more info, check out the air trait page at my source.
You are right it doesn't really dry the air. The relative humidity of the heat up air will be smaller amount than that of the incoming cold air, but will increase again as the upper air cools. Indoor air get drier in the winter because the outdoor nouns is drier.