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D.E. Anderson
D.E. Anderson, Industrial Refrigeration Service Manager
Category: HVAC
Satisfied Customers: 198
Experience:  15 years experience. Design, install, service of residential & commercial hvac/r equip.
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I am installing a Honeywell Wi-Fi Smart Thermostat,

Customer Question

I am installing a Honeywell Wi-Fi Smart Thermostat, RRTH9580WF, in my house. I have a Trane XL90 Furnace. Where does the blue wire, commonly referred to as the C wire, get connected to the furnace. It was not connected using my old thermostat.
Submitted: 1 year ago.
Category: HVAC
Expert:  D.E. Anderson replied 1 year ago.

Hi, I'm more than happy to help you out. You would connect your common wire (AKA C-wire/Blue wire) to the B terminal inside your furnace. Try that out and let me know how it works. Feel free to ask if you have any further questions. Thanks.