Diagram #10: Forced Air Furnace having a replacement air supply duct together with an exhaust fan controlled by a designated ventilation switch and/or an interval timer. Thermostat also opens the replacement air supply damper during firing.

 

ADDED: 1. Replacement Air Damper with Relay (HAC-0x11-OPC)  2. Ventilation Switch with Controlled and Regular 120Vac, 3-Wire supply to furnace area.

3. Relay Adaptor with Interval Timer (TMADP-1102-TPX) as control centre.

OPERATION: 1. Replacement Air Damper opens during furnace firing.

2. Ventilation Switch turns on Ventilation Fan, opens Replacement Air Damper and turns on Furnace Fan simultaneously without interfering with the Air Conditioner. 3. Interval Timer, with minimum or multiple consecutive settings of 15 minutes each, can turn on Ventilation Fan, open Replacement Air Damper and turn on Furnace Fan simultaneously. 4. Opt. Switch (i.e. toggle switch, timer, de-humidistat) allows full control of the Replacement Air Damper to open provided it is a PC type.