furnace - How do I identify the C terminal on my HVAC How do I identify the C terminal on an HVAC, furnace, or boiler? If the terminals don't have a screw labeled C what should I look for on the wiring diagram? What steps should I take if a wiring diagram cannot be found or if it indicates that a C terminal doesn't exist? Wiring Diagrams Locate the schematic. In most cases, a wiring diagram[PDF] TYPICAL WIRING DIAGRAM MANUAL - H-Mac TYPICAL WIRING DIAGRAM MANUAL INDOOR GAS-FIRED UNIT HEATERS AND DUCT FURNACES Standard (Natural Vent) or Power Vented ON THESE WIRING DIAGRAMS Manual Fan Switch Terminal Blocks 1-Stage Thermostat 1-Stage T834H Thermostat 2-Stage 24V Thermostat OPTIONS NOT INCLUDED ON THESE WIRING DIAGRAMS Wireing an Aprilaire 700 to Waterfurnace 5 | GeoExchange wwwxchange››General DiscussionsMar 06, 2015Wireing an Aprilaire 700 to Waterfurnace 5. Discussion in 'General Discussions' started by Sherwoodator, Mar 5, I have included the schematics from my Waterfurnace 5 and the Aprilaire 700. Thanks in advance. Sherwoodator, Mar 5, Wiring between the C and G should get you what you want. Waterfurnace Humidifier - Best Place to Find Wiring and Waterfurnace Humidifier. The wiring diagram on the opposite hand is particularly beneficial to an outside electrician. Sometimes wiring diagram may also refer to the architectural wiring program. The simplest approach to read a home wiring diagram is to begin at the source, or the major power supply.