The HVAC guys were back again, and they were kind enough to provide us with some photos of their work in the attic.

The main trunk duct carries conditioned air from the furnace to the rest of the house.  The trunk is made from a rigid fiberglass duct board which by itself has some insulating properties. Extra insulation is wrapped around the trunk when it is installed.

Left: The trunk duct carries the conditioned air throughout the house.
Right: Extra insulation for the trunk.

The view on the left below shows the round connectors for the flexible fiberglass ducts that go to individual ceiling registers. In the background is part of the cold air return system.

Left: Two connectors for flexible round ducts. In the background is one of three return plenums.
Right: A box fan provides little relief from the 100°+ heat in the attic.

Meanwhile, back in the living quarters, flexible fiberglass ducts are connected to ceiling registers.

The flexible round ducts run from the trunk to the individual registers.

Register in the walk-in closet.

We greatly appreciate the hard work by the HVAC guys. The conditions are miserable in the attic. Outside temperatures topped 90° this week, so it has to be 110–120° in the attic. THANK YOU!