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Phil, Mechanical Engineer
Category: HVAC
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Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I'm trying to install a new Honeywell wifi thermostat model

Customer Question

Hello, I'm trying to install a new Honeywell wifi thermostat model Rth8580wf to replace a carrier tp-prh01-a thermostat. There are only two wires from the wall, a red and white. The red went to the v+ and white went to vg on the carrier tstat. Help on how to connect the Honeywell please?
Submitted: 11 months ago.
Category: HVAC
Expert:  BillyHvac replied 11 months ago.

Hello,

I am afraid this will not work without seeing if wiring can be changed in furnace. You have a "communicating" system where the thermostat talks constantly back and forth with the furnace. The wifi cannot do this...and the wifi also needs a 3rd wire to go on terminal C.

How many wires total in the cable and what is furnace model number?

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