HMI Hoyme Manufacturing Inc. Special Note: Circuits are colored for clarification only and are not necessarily those found in actual installations.  Wires of the Combustion Air Damper, however, are colored as shown.

 

Diagram #2: Two Mid-efficient Forced Air Furnaces plus AC (If applicable).ADDED: Combustion Air Damper for two appliances *(HOM-0x12-SF2)* but having only one combustion air supply duct. *(Damper has two separate operating circuits)*

 

OPERATION: Combustion Air Damper is interlocked to both appliances so that the damper proves to be open for combustion when either one or the other or both furnaces are firing.

0619 Printed in Canada