If you’re lacking a C wire and have at least four wires at your thermostat to work with (refer to this article if you only have two wires), you’ll want to install the Power Extender Kit (PEK). The PEK gets installed at your furnace control board and is wired in with your existing thermostat wires to create a C. Installation is quite easy—just follow the steps below!
1) Turn off power to your HVAC equipment before doing any re-wiring
2) Locate where your four thermostat wires (R, G, Y, W) are connected at your furnace control board; they should be connected to standard R, G, Y, W terminals on the board, or possibly spliced into other wires leading back to the board
* Depending on your setup, you may see another wire already connected to the C terminal, as well as one connected to the Y terminal—these two wires from this separate bundle are coming from your outdoor compressor unit and need to remain connected for your air conditioner to work, so don’t remove these two wires!
3) Remove these four wires from their current location and insert them into their respective terminals on the PEK (R, G, Y, W)
4) You’ll see five wires coming off the other side of the PEK—R, G, Y, W, and C—connect these five wires to their respective terminals on the furnace control board
* If you have any splice points on your thermostat wires, you’ll need to install the PEK at those splice points! Failure to do so may cause your equipment not to run properly. The diagram below illustrates how the PEK should be installed when splice points are present.
5) Once the PEK is installed and you’ve confirmed all wires are securely connected, you can close the panel on your furnace and return to the ecobee
6) Wire the ecobee as follows:
- R wire >> RC terminal
- G wire >> C terminal
- Y wire >> PEK terminal
- W wire >> W1 terminal
7) Place your ecobee on the wall mount, restore power to your HVAC system and watch your ecobee4 come to life!
If your ecobee does not power on after following these steps above, please refer to this article for further troubleshooting or reach out to our Support team at 1-877-932-6233. Agents are available from 8:00AM – 12:00AM EST Monday through Friday and 9:00AM – 9:00PM Saturday through Sunday.
To ensure prompt service, please have wiring pictures at the thermostat, furnace board, and Power Extender Kit handy.