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Ecobee3 wiring issue (G and Y are tied together in the system)

HHvelujHHveluj Member
edited August 2016 in ecobee


Long story short, tried installing smart thermostat Ecobee3 - didn't work. One of the potential culprits is the fact that for some reason the G and Y wires are tied together when they exit the unit (photo attached). R and W and C are all separate, however C doesn't make it to the thermostat. All these wires are tied to thicker wires (original thermostat must've been line voltage), which then somewhere in the wall/ceiling are then tied to small wires that come to the current thermostat.
So, three questions:
- Why would G and Y be tied together?
- Could the C wire be used anywhere in the system? It's not making it to the thermostat now.
- Is there a way to install the smart thermostat without a complete rewire of the system? The thermostat would need at least R, W, G, Y (and then there's a way to use the "Power Extender Kit" to tie the C into them).

Thank you very much in advance!



  • kevinmcckevinmcc Macomb, ILMember

    G normally tells the air handler to run the fan.

    Y normally tells the air handler to run fan and AC to run.

    Really depends on the air handler and prior thermostat as to why the G and Y were tied together.

    You have specific make and model of the air handler, and picture of wiring there?

  • Sorry, should've mentioned - the unit is Lennox WhisperHeat G20Q3E-75-7.
    Here's the picture of wiring with PEK. Without PEK the color coding is the same in WGYR, C is orange, but it doesn't go to the thermostat.

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