Look at the photo below. It’s the heater in a cheap RV. A couple posted this at RV Horror Stories. They were having trouble heating the front part of their RV. They checked around with a camera but couldn’t find anything wrong. So, “we removed the board under our bed which gave us access to the furnace.”
And this is what they found. To save labor, the RV manufacturer simply coiled up the heating ductwork to fit in the small compartment rather than shorten it to fit properly. The result is that the hot air had to travel much farther to reach the front of the RV, losing precious heat every extra foot of the way.
Of course it doesn’t help that the ducting is not even connected to the heater. It may have come from the factory that way or vibrated out.
But the obvious shortcut here is that rather than spend a little extra to shorten the ducting, the manufacturer saved on labor by coiling it up. And the buyers got suckered because they didn’t examine the “stick and tin” RV close enough before buying it.