"Putting a Damper on Cold Air"

Timer, vent switch, replacement air, Power Open, and an exhaust fan with 3-way ventilation switch

HMI Hoyme Manufacturing Inc. Special Note: Circuits are colored for clarification only and are not necessarily those found in actual installations.

Diagram #9C1: Forced Air Furnace having a replacement air supply duct and an exhaust fan controlled by a designated ventilation switch, a 3-way ventilation switch and an Interval Timer Adaptor.

1. Replacement Air Damper, power open, (HAC-0x10- OPO) 

2.Ventilation Switch supplies a Controlled and a Regular 120Vac (3-Wire) power supply to the furnace area. 

3. A 3-way Ventilation Switch to control ventilation fan only. 

4. An Interval Timer Adaptor (TMADP-1102-TPX) which functions as a complete control centre.

OPERATION: 

1. Furnace fires with thermostat signal. 

2. Ventilation switch turns on Ventilation Fan, opens Replacement Air Damper and turns on Furnace Fan simultaneously.  

3. Three-way Ventilation Switch turns on the Ventilation Fan only. 

(Not recommended unless living in coastal climates warmer than -10C and/or ample replacement air is supplied).  

4. Optional switch (i.e. toggle switch, timer, de-humidistat) connected between #1 and #2 of the Adaptor allows full control of the PO Replacement Air Damper to open as required.

N.B. Replacement Air Damper is not affected by the ‘Manual’ setting of the furnace fan.

1222-ld - Printed in Canada

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