120Vac vent switch, combustion air(2 furnaces), replacement air
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 #5B: Two Furnaces having a common combustion air and two replacement air supply ducts together with an exhaust fan controlled by a designated ventilation switch.
ADDED: 1. Combustion Air Damper (HOM-0x12-SF2) 2. HAC-0x10-OPC connected to the primary furnace. 3. ADP-1101-05A connected to the primary furnace only. 4. HAC-0x11-OPC damper with relay is connected to the secondary furnace.
OPERATION: 1. Replacement Air Damper HAC-0x10-OPC is inter-connected to the Combustion Air Damper so that this damper opens during firing of either or both furnaces and closes when firing stops. 2. Ventilation Switch turns on the exhaust fan, the furnace fan and opens the primary HAC damper simultaneously. 3. The secondary damper HAC-0x11-OPC opens only when the secondary furnace fires. 4. Optional switch (i.e. toggle switch, timer, de-humidistat) on each HAC damper allows independent control of each damper.
0828 Printed in Canada
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