A new system of inflatable dampers makes it possible to retrofit forced hot air heating into multiple zones without disassembling and reassembling the ductwork. The control panel of the Arzel Comfort Control Zoning System houses the vacuum and pressure pumps that inflate and deflate balloon-like dampers, which fit most common sizes of round, rectangular, and flexible ducts. The dampers are inserted through a hand-sized hole in the duct, which is then sealed with a magnetic vinyl patch (similar to magnetic vehicle signs). The air lines attach to a nipple, which pokes through a smaller hole and holds the damper in place. The cost to the trade for a typical two-zone system — including 12 dampers and the control panel —
