Sheet Metal Ductwork After Cleaning: Inside a Clean Plenum and Trunk

Nobody's in the shot, just a light moving across the inside of a plenum, the sheet metal box on the furnace or air handler that the trunk lines run from. The walls show spangle, the crystal pattern zinc leaves on galvanized steel, and the light bounces straight off it with nothing dulling the shine.

Then the camera tips down the trunk, the main rectangular duct. Its joints read as clean lines, and small bright points at each seam, where the fasteners come through, catch the light all the way to the far end.

This was shot on a July job, 33 minutes after a clip from the same job that caught a duct wall still half covered in dust and dark debris.