An ecobee thermostat installation is a low-voltage wire swap: you turn off the power, label the wires on your old thermostat, connect each one to the matching terminal on the ecobee backplate and finish setup on the screen and in the ecobee app. The steps are the same on every model, and ecobee says most homes take about 45 minutes. What changes from one model to the next is the set of terminals, where a single R wire goes and whether a Power Extender Kit comes in the box, so this guide covers how to install ecobee thermostat models step by step, then the wiring for each one.
If you’re still choosing a model, our comparison of the ecobee Essential, Enhanced and Premium explains the differences.
The quick version
Here’s the whole job, start to finish:
- Install the ecobee app and check that your system is compatible.
- Turn off the power at the breaker and check the system won’t turn on.
- Take a photo of the old wiring and label each wire by its terminal letter.
- Remove the old thermostat and its base.
- Level the ecobee backplate, drill the holes and screw it to the wall.
- Connect each wire to its matching terminal and tug it to check it’s held.
- Press the thermostat onto the backplate and turn the power back on.
- Follow the setup on the screen, register the thermostat in the app and test it.
Before you start
Find your model. The model name is on the box and in the app once you add the thermostat. It tells you which terminals your backplate has:
| Model | Terminals | One R wire goes in | Two R wires (dual transformer) | Power Extender Kit |
|---|---|---|---|---|
| Smart Thermostat Premium | Rc, Rh, C, G, Y1, Y2, W1, W2, O/B, PEK+, ACC+, ACC- | Rc | Supported | In the box |
| Smart Thermostat Enhanced | R, C, G, Y1, Y2, W1, W2/OB, PEK+ | R | Not supported | In the box |
| Smart Thermostat Essential | R, C, G/PEK, Y1, W1, OB | R | Not supported | Sold separately |
| Older models (SmartThermostat with voice control, ecobee4, ecobee3 lite) | Rc and Rh, plus the usual C, G, Y, W and O/B | Rc | Supported | In the box with the ecobee4 and ecobee3 lite |
The fourth current model, the Smart Thermostat Lite, is sold only through HVAC installers, so your installer handles it.
Check that it will work. ecobee thermostats are built for 24 V heating and cooling systems, which covers most furnaces, air conditioners, boilers and heat pumps in US homes. ecobee’s compatibility checker walks you through it, or take the cover off your old thermostat and look for these signs that your system isn’t compatible:
- Wires labeled L1 and L2, or a thermostat marked 110, 120 or 240 V. That’s a line-voltage system, usually electric baseboard heat.
- Terminals labeled 1, 2, 3, 4 or A, B, C, D. That’s a proprietary communicating system.
- A millivolt system, usually a gas wall or floor heater.
- Wires on W3 or Y3, which means a third stage of heating or cooling. ecobee doesn’t support it.
Also check for two R wires. If an Rc wire and an Rh wire both come out of the wall, you have a dual-transformer system (often a boiler with separate air conditioning). The Premium supports it; the Enhanced and Essential don’t.
Gather your tools. ecobee lists a drill with a 3/16 inch bit, a flathead screwdriver and a Phillips screwdriver. A pencil, a hammer for the wall anchors and a wire stripper help too, plus your phone for photos and the app.
Know when to call a pro. ecobee recommends a professional if you have separate O and B wires on a heat pump. Call one too if you have more than one G wire (a fan with several speeds controlled by the thermostat), since ecobee warns that a wrong setup can damage the system, or if you have a dual-transformer system and a model that doesn’t support it. Our guide to smart thermostat installation cost covers what pros charge.
How to install an ecobee thermostat, step by step
These steps follow ecobee’s installation guides for the Premium, Enhanced and Essential. For the same job on other brands, see our guide on how to install a smart thermostat.
1. Start in the ecobee app
Download the ecobee app, create an account (or sign in) and add a new device. On the Premium and Enhanced, scan the QR code on the back of the thermostat. The app then shows installation steps and diagrams for your wiring, and it asks you to enter which terminals your old thermostat uses.
2. Turn off the power and check it’s off
Turn off the breaker or switch for your heating and cooling system. To check, turn on the heat (in winter) or the air conditioning (in summer) at the old thermostat and wait a few minutes: no air should come from the vents. If you have a boiler, check that the main flame has gone out.
3. Photograph and label the wires
Take the old thermostat off its base (most pull straight off; some have screws). Take a clear photo that shows the letter next to each terminal. Then:
- Put a label from the ecobee box on each wire as you disconnect it, using the terminal letter, not the wire color.
- Leave any jumper alone. A jumper is a short wire or metal clip between two terminals, often R and Rc. It stays on the old base: ecobee says not to jumper any R wires on the ecobee.
- Label only the wires that come out of the wall.
4. Remove the old thermostat
Unscrew the old base from the wall. If your old thermostat has a sealed glass tube of mercury inside, take it to your local hazardous waste facility rather than putting it in the trash.
5. Mount the backplate
The Premium and Enhanced come with a trim plate that covers marks and holes from the old thermostat: snap it onto the backplate first if you want it. For the Essential, the Trim Kit is sold separately, and ecobee says you need it if the thermostat mounts on an electrical box.
Pull the wires through the center of the backplate and hold it level against the wall (the Premium’s backplate has a built-in bubble level). Mark the screw holes, drill them with the 3/16 inch bit, tap in the drywall anchors and screw the backplate to the wall.
6. Connect the wires
Press down the lever on a terminal, push the matching wire into the side of the terminal (not the front) and let go: the lever stays down when the wire is held. Do the same for each wire, then tug each one gently to check it’s secure. If you have one R wire, put it in Rc on the Premium and in R on the Enhanced and Essential.
Push the extra wire back into the wall. A large hole behind the thermostat lets drafts in and can affect the temperature reading, so ecobee suggests sealing it with plumber’s putty.
7. Attach the thermostat and turn the power on
Press the thermostat onto the backplate until it clicks into place. If it rocks or isn’t flush with the wall, push the wires further in. Then turn the breaker back on. The screen should say “Hi”, which means it has power.
8. Finish setup and test it
The thermostat walks you through setup on its screen. It shows the wires it detected, and you confirm them or fix them. Then you choose your system type and fan settings, connect to Wi-Fi and set your country and time zone. At the end, it shows a 4-digit registration code: in the ecobee app, add the thermostat and enter the code within about an hour, before it expires.
After setup, the thermostat may show “Calibrating” for up to 20 minutes before it heats or cools. Then run the heat, the cooling and the fan for a few minutes each. You can also test each one from the thermostat’s settings, under Installation Settings and then Test Equipment. If you have SmartSensors to add, our ecobee SmartSensor guide covers pairing and placement.
Ecobee thermostat wiring diagram: what goes where
Most of an ecobee installation is a straight letter-to-letter match: C to C, G to G, Y1 to Y1, W1 to W1. These are the wires that confuse people:
- One R wire. Whether it’s labeled R, Rc or Rh, it goes in Rc on the Premium and older ecobee models, and in R on the Enhanced and Essential.
- Two R wires. On the Premium, Rc goes in Rc and Rh goes in Rh. ecobee says the rest of a dual-transformer installation is different from a standard one, so follow its dual-transformer steps in the app or hire a pro. The Enhanced and Essential don’t support it.
- Second stages. The Essential has no W2 or Y2 terminal. Its OB terminal handles either a heat pump’s O/B wire or one second stage of heating or cooling, so it can run 2 stages of heat with 1 of cooling, or the other way around. The Enhanced shares one terminal between W2 and O/B.
- Heat pumps. Y1 runs the compressor, and the O/B wire goes in O/B (W2/OB on the Enhanced, OB on the Essential). ecobee says to connect an AUX, AUX1 or W2 wire to W1, a second aux stage (AUX2) to W2 on the Premium, and an E wire to W1. Our guide to aux heat explains these terms.
- A B wire with no O wire. Connect it to O/B. However, ecobee notes that a wire labeled B can sometimes be the common wire, so check where it goes at the equipment.
- Wires you don’t need. S wires (outdoor sensor) and L wires (indicator lights) aren’t used: the ecobee gets weather data over Wi-Fi. Tape off spare wires and tuck them back into the wall.
Our thermostat wiring diagram guide shows how common systems are wired at the furnace too.
If you don’t have a C wire
Every ecobee runs on constant 24 V power from a C wire (the common wire) and has no batteries. If your old thermostat had no C wire, you have a few options:
- Use a spare wire. Look for an unused wire tucked behind the old base. Connect it to C at the thermostat and to C on the furnace or air handler’s control board, then close the furnace cover fully (some systems won’t run with it open).
- Install the Power Extender Kit (PEK). It installs at the furnace control board and combines the jobs of the Y and G wires so one of them can work as a C wire. ecobee says it needs at least four wires (R, G, Y and W), although the Essential’s guide lists R, G and Y as the minimum. It doesn’t work with dual-transformer, heat-only, fan coil or communicating systems. It comes with the Premium and Enhanced, and costs extra for the Essential.
- Use the G wire as C. You move the G wire to C at both ends and add a jumper between Y and G on the control board. However, you lose independent fan control: the fan only runs with heating or cooling.
- Call a pro to run a new cable, or choose a thermostat built for this from our best smart thermostats without a C wire guide.
At the thermostat, the PEK wiring depends on the model:
- Premium: R to Rc, G to C, Y to PEK+, W to W1.
- Enhanced: R to R, G to C, Y to PEK+, W to W1. The PEK+ terminal can run the PEK or one accessory (a humidifier, dehumidifier or ventilator), not both.
- Essential: R to R, G to C, Y to G/PEK, W to W1.
A heat-only system with two wires can’t use the PEK at all. ecobee points to an add-on like the Fast-Stat Common Maker, which may need a separate transformer, or a new cable. Our C-wire adapter guide compares the options.
If it doesn’t work after installing
Most problems after an ecobee thermostat installation are power or wiring problems:
- The screen stays blank. Check that the breaker is on, the furnace cover is fully closed and every wire is seated in its terminal. Check that a single R wire is in the right terminal for your model, and if you installed the PEK, check its wires at the furnace.
- It says “Calibrating”. The thermostat has just powered up and needs up to 20 minutes before it heats or cools.
- The wrong wires show up in setup. Turn off the power before you change any wiring. If the wiring is right but setup missed a wire, select it manually. To run the wiring setup again later, go to the thermostat’s settings, then Installation Settings, Equipment and Reconfigure Equipment.
- The cooling doesn’t start right away. The thermostat waits 5 minutes after the last cooling cycle by default to protect the compressor.
Our guide to ecobee thermostat problems covers each fix in more detail.
The bottom line
For most homes, an ecobee thermostat installation takes the same steps on every model: power off at the breaker, photograph and label the wires, leave the old jumper behind, mount the backplate, connect each wire to its matching terminal, press on the thermostat and finish setup in the app. Check your terminals and your C wire before you start, and call a pro for line-voltage, communicating or three-stage systems, or for a dual-transformer system on the Enhanced or Essential.
Can I install an ecobee thermostat myself?
Yes, in most homes. ecobee says the job takes about 45 minutes with a drill and two screwdrivers: turn off the power, label the wires, mount the backplate and connect each wire to its matching terminal. Call a pro for separate O and B wires, more than one G wire, or a dual-transformer system on a model that doesn’t support it.
Does an ecobee thermostat need a C wire?
Yes. Every ecobee runs on constant 24 V power and has no batteries. Without a C wire, you can use a spare wire or the Power Extender Kit, which comes with the Premium and Enhanced and costs extra for the Essential.
Where does a single R wire go on an ecobee?
In Rc on the Smart Thermostat Premium and older models like the ecobee4 and ecobee3 lite. The Enhanced and Essential have a single R terminal, so the wire goes in R, whether it’s labeled R, Rc or Rh.
What do I do with the jumper wire when installing an ecobee?
Leave it on the old thermostat’s base. ecobee says not to jumper any R wires on the ecobee, so only connect the wires that come out of the wall.
Does ecobee work with a dual-transformer system?
The Smart Thermostat Premium and older ecobee models do. The Enhanced and Essential don’t. If an Rc wire and an Rh wire both come out of the wall, you have a dual-transformer system, and the Power Extender Kit can’t be used with it.
How do I register my ecobee after installing it?
At the end of setup, the thermostat shows a 4-digit registration code. In the ecobee app, add a device, choose the ecobee thermostat and enter the code. It expires after about an hour, but you can get a new one from the thermostat’s settings under Registration.
Written by Evan Mercer
Founder & Lead Researcher, Smart Home Matrix
Evan digs through spec sheets, firmware changelogs, and thousands of owner reviews so you don’t have to. Every guide starts with a compatibility check and ends with picks he would install in his own home. Read more about Evan and this site, or see exactly how we choose products.