Diagram #8C1: Two Forced Air Furnaces sharing a common replacement air supply duct controlled by one Power Open fresh air damper. The damper opens when either furnace fires. If using a Power Close damper, go to wiring Diagram # 8C for details.
1. Replacement Air Control Damper, Power Open (HAC-0x1O-OPO) where ‘x’ = diameter of the damper. 2. 24Vac Relay Adaptor (ADP-0241-05A) to operate the damper from either furnace.
OPERATION: 1. The Power Open (PO) Replacement Air Control Damper will open when the thermostat of either furnace asks for heat, and will remain open until both thermostats turn the furnaces off.
N.B. Replacement Air Damper is not affected by the ‘Manual’ setting of the furnace fan or by the operation of an Air Conditioner.