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I do not have a “C wire” or “Common wire”. Can I install ecobee residential thermostats?

I do not have a “C wire” or “Common wire”. Can I install ecobee residential thermostats?

  1. C-wire or common wire may not exist in your current thermostat if the thermostat is battery powered. However ecobee residential thermostats can be installed without the C-wire.
    1. ecobee3 – ecobee3 package contains a Power Extender Kit (PEK) in the box which is required for installation when a C-wire is not available on your current thermostat. For more details, please refer to Installation Guide Step 3 – Install Power Extender Kit.
    2. Smart Si – Smart Si can also be installed without a C-wire. This setup requires repurposing the G wire (fan) as a C wire and to let the furnace control the fan. More details are available here. The wiring diagram is available in the install guide “Single Stage Heat/Cool with 4 wires at the thermostat”.
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