Our bedroom is the furthest from the furnace in our class A. As the warm air travels a further distance in the cold ducts (starting out) it makes sense to me that at first the air is not as warm as at the other vents and the airflow is not as hard either. After the furnace has run for a little, the air is nice and warm, but less airflow than the main living area. We haven't tried heating to 80, but I'm sure it would do it, it would just run a lot and use tons of propane if it were winter and cold out.