How to Install ecobee3 lite (no C-wire available)

First things first. Here’s what you’ll find in the box.

You’ll also need these tools:

 
STEP 1

Power off your Heating, Ventilation and Air Conditioning (HVAC) system by using the master switch or circuit breaker box. This is important for your safety.

 

STEP 2

Confirm your system is off by turning on your heat (during winter) or your AC (during summer). Wait a few minutes - you should not feel air coming from your vents.

 

STEP 3

 

 

 

 

STEP 4


Take a picture of the wires connected to the terminals of your old thermostat.You may need to reference this photo later on.

 

 

 

 

 

Install your ecobee without a C wire

If you don’t have a C wire, you’ll need to use the Power Extender Kit (PEK) included to reliably power your ecobee.

 

 

 

 

The Power Extender Kit requires your system to have the following wires:

4 wires: W/W1, Y/Y1, G and R (or RC or RH)

OR

3 wires: Y/Y1, G and R (or RC or RH)

 

 

STEP 5

Take your Power Extender Kit, wire labels, tools, your smart phone, and go to your HVAC system.

 

 

STEP 6

Open your HVAC system’s cover to reveal the control board.

 

 

STEP 7

Take a picture of the wires connected to your control board. You may need to reference this photo later on.

 

 

STEP 8

Label only the R, Y or Y1, G and W or W1 wires with the matching labels provided. If you have more than one wire going into these terminals, only label those coming from your thermostat.

 

 

STEP 9

Disconnect the labeled R, Y, G and W wires from the control board.

 

STEP 10

Connect the wires you disconnected from the control board into their matching gray terminal blocks on the Power Extender Kit.

 

 

STEP 11

Tug on the wires gently to ensure they are securely connected.

 

STEP 12

Connect the 5 white wires coming out of the Power Extender Kit to the corresponding terminals on your control board.

 

 

 

 

STEP 13

Mount the Power Extender Kit inside your HVAC system, taking care not to strain the wires. Close the HVAC cover panel securely and return to your thermostat.

 

 

STEP 14

Back at your thermostat: Carefully disconnect and label the wires from your old thermostat one at a time, using the labels provided.

 

STEP 15

Unscrew the mounting plate of your old thermostat to remove it from the wall.

 

STEP 16

Decide if you want to use the trim plate with your ecobee. The trim plate is useful if you want to hide marks or holes on the wall left by your old thermostat.

STEP  17 : OPTIONAL

If using the trim plate, align the mounting holes on the trim plate and backplate and press them into place together.

STEP 18

Pull the wires through the hole in the middle of the backplate and then attach it to the wall using the drywall anchors and screws provided.

 

 

STEP 19

First, connect these 3 wires as shown:

 

STEP 20

Tug on the wires gently to ensure they are securely connected.

 

STEP 21

Carefully push any excess wire back into the hole and ensure there are no drafts coming from the hole(s) in the wall.

 

STEP 22

Gently press your ecobee thermostat into the backplate until it ‘clicks’ into place.

 

STEP 23

Turn the power to your HVAC system back on using the master switch or at the circuit breaker box.

 

STEP 24

Say hi to your new ecobee! The screen will power on and guide you through the set-up and registration.

 

 

 See installation video: Installing ecobee3 lite without C-wire