Heating & Air Conditioning Electrical Wiring

4 wire thermostat to 2 wire

2 years ago

Hello, someone gave me a more modern thermostat with a colorful display. I have a gas furnace with central air which originally came with one of those old mercury thermostats. The issue is the new one is a 2 wire but my old one is a 4 wire (green, yellow, white, and red). I ran a search here but have not come to understand what I need to do or if it's compatible. The old one on the left of course...

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Comments (2)

HU-369918894
Original Author
2 years ago
last modified: 2 years ago
never mind. I found out this is for wireless modules that I don't have. The two wires are only for power and to transmit instead of the other wires for signaling.

Just a thought - Maybe they could have made a small module that can be added under the thermostat to control those wire signals from that point instead of modules located near the furnace.
wdccruise
2 years ago
"Maybe they could have made a small module that can be added under the thermostat to control those wire signals from that point instead of modules located near the furnace."

No, because that would have required that all the wires were available at the thermostat location. This thermostat is designed to require only two wires at the thermostat so it wouldn't have made sense to do what you suggest.

According to the installation manual step 7, the thermostat does allow you to configure a wide variety of features and the thermostat is programmable. Unfortunately, it requires the extra-cost gateway for wi-fi.
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