I pulled the Fifth Wheel home last weekend and did the usual systems checks. Got to the furnace and there was little heat making its way to the inside but the garage was nice and warm.
Pulled the wall off last night in the garage to find a duct had a hole in it, maybe a mouse or maybe not. The stock ductwork is this type $12.00 for 25 ft
I replaced it with gas dryer vent. $5.00 for 8 ft.
I can understand the need to reduce weight but the temperature that furnace can deliver actually melted the duct once the hole was chewed in it. If you have heat loss check for a duct that have a hole.