Colored Wiring Diagram #8D
Two Forced Air Furnaces sharing a replacement air supply duct controlled by one fresh air damper with Power Close Damper
HMI Hoyme Manufacturing Inc. Special Note: Circuits are colored for clarification only and are not necessarily those found in actual installations.
Diagram #8D: Two Forced Air Furnaces sharing a common replacement air supply duct controlled by one Power Closed fresh air damper. (For Power Open damper, go to Diagram #8D1)
The damper opens when either furnace fires. Damper also opens on the cooling cycle of furnace #2 for night cooling.
(Air Conditioner is not used in this circuit but uses night air to do the job.)
1. Replacement Air Control Damper, Power Open (HAC-0x11-OPC) where ‘x’ = diameter of the damper.
2. 24Vac Relay Adaptor (ADP-0241-05A) to operate the damper from either furnace.
3. Additional Adaptor (ADP-0241-05A) to operate the damper on the cooling cycle of furnace #2.
1. The Power Close (PC) 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.
2. Damper will open on cooling cycle of furnace #2.
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N.B. Replacement Air Damper is not affected by the ‘Manual’ setting of the furnace fan or by the operation of an Air Conditioner.
1222-ld - Printed in Canada
Last Updated (Tuesday, 20 October 2015 15:37)