Diagram #8: Forced Air Furnace having a replacement air supply duct together with an exhaust fan controlled by a designated ventilation switch that sends a 24Vac signal to the furnace area.

 

ADDED:  1. Replacement Air Control Damper with Relay (HAC-0x11-OPC)    

2. Ventilation Switch which supplies Controlled 24Vac to furnace area. 

3. 24Vac Relay Adaptor (ADP-0241-05A) to function as a control centre.

 

OPERATION: 1. Replacement air damper opens to provide fresh air 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. Optional Switch (i.e. toggle switch, timer, de-humidistat) allows full control of Replacement Air damper to open provided it is a PC type.