Two Forced Air Furnaces sharing a Replacement Air Supply Duct controlled by One Fresh Air Damper with Power Close Damper:
#8D. Two Forced Air Furnaces Sharing a Replacement Air Duct with a Power Close Fresh Air Damper (HAC-0x11-OPC) c/w Relay with Two Adaptors (ADP-0241-05A) controlling the Replacement Air Damper for either Furnace.
HMI Hoyme Manufacturing Inc. Special Note: Circuits are colored for clarification only and are not necessarily those found in actual installations. Combustion Air Damper Wires, however, are colored as shown.
Diagram #8D: Two Forced Air Furnaces sharing a common Replacement Air supply Duct controlled by one Power Closed Fresh Air Damper. 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.)
- Replacement Air Control Damper, Power Open (HAC-0x11-OPC) where ‘x’ = diameter of the Damper
- 24Vac Relay Adaptor (ADP-0241-05A) to operate the Damper from either Furnace
- Additional Adaptor (ADP-0241-05A) to operate the Damper on the cooling cycle of Furnace #2
OPERATION:
- 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
- Damper will open on cooling cycle of furnace #2
N.B. Replacement Air Damper is not affected by the ‘Manual’ setting of the Furnace Fan or by the operation of an Air Conditioner