120Vac vent switch, combustion air(2 furnaces), 2 replacement air dampers (Power Close)
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 or timer.
4. HAC-0x11- OPC damper with relay is connected to the secondary furnace.
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 and/or timer 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.
N.B. Replacement Air Dampers are not affected by the ‘Manual’ setting of the furnace fan.
1222-ld - Printed in Canada
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