Installing Your Google Nest Learning Thermostat (3rd Gen)

Before You Begin

The Google Nest Learning Thermostat (3rd Gen) is the classic round smart thermostat that learns your schedule and preferences to automatically adjust heating and cooling. Its iconic stainless steel design includes a high-resolution circular display and a rotating dial for manual temperature adjustments. This guide walks you through the full installation process.

What You Will Need

• Google Nest Learning Thermostat (3rd Gen)
• The included base plate, screws, and trim plate
• The Google Home app (or legacy Nest app) installed on your smartphone
• A Google account
• A compatible HVAC system (check compatibility at the Nest website or in the app)
• A Phillips-head screwdriver
• A drill (optional, for pilot holes)
• Wire labels (included in the box)
• A C-wire or Nest Power Connector if your system lacks a C-wire

Step 1: Check System Compatibility

1. Before purchasing or starting installation, verify your HVAC system is compatible. Visit the Nest compatibility checker online or use the Google Home app.
2. Remove the faceplate from your current thermostat to expose the wiring connections.
3. Identify and record which wires are connected and their terminal labels (R, W, Y, G, C, O/B, etc.).
4. The Nest 3rd Gen works with most 24V systems including forced air, radiant, heat pump, and dual-fuel systems. It does not support high-voltage systems (110V/240V baseboard heaters).
5. If your system does not have a C-wire, you can use a Nest Power Connector (sold separately or sometimes included) to provide steady power to the thermostat.

Step 2: Turn Off HVAC Power

1. Locate the circuit breaker or power switch for your heating and cooling system and turn it off.
2. Verify the system is off by adjusting your old thermostat and confirming the HVAC does not activate.
3. This step is essential for your safety and to prevent damage to the thermostat or your HVAC system.

Step 3: Remove Your Old Thermostat

1. Remove the faceplate from your existing thermostat.
2. Take a clear photo of the wiring for reference.
3. Apply the included wire labels to each wire, matching the terminal letter it is connected to.
4. Disconnect the wires one at a time from the old base plate.
5. Remove the old base plate from the wall. Fill any holes that do not align with the Nest base plate if desired.
6. If there is a wire labeled C, note it — this is your common wire that provides continuous power.

Step 4: Install the Nest Base Plate

1. Thread the thermostat wires through the center of the Nest base plate.
2. Hold the base plate against the wall and use the built-in bubble level (printed on the base plate) to ensure it is straight.
3. Mark the screw holes, drill pilot holes if necessary, and attach the base plate with the included screws.
4. If the base plate does not fully cover the old thermostat's footprint, attach the included trim plate behind the base plate first.

Step 5: Connect the Wires

1. Press each connector tab on the Nest base plate to open the terminal.
2. Insert each labeled wire into its matching terminal on the Nest base plate (R goes to R, W to W1, Y to Y1, G to G, etc.).
3. Release the tab to secure each wire. Give each wire a gentle tug to ensure it is held firmly.
4. If you are installing a Nest Power Connector for the C-wire, follow the separate installation instructions for connecting it at your furnace before proceeding.

Step 6: Attach the Thermostat Display

1. Align the thermostat display over the base plate and press it straight onto the connectors until it clicks into place.
2. Turn the HVAC power back on at the circuit breaker.
3. The Nest thermostat will power on and begin its on-screen setup sequence.

Step 7: Complete Setup on the Thermostat

1. Follow the on-screen prompts to select your language, connect to your Wi-Fi network, and sign in to your Google account.
2. The thermostat will confirm which wires it detected and identify your HVAC equipment.
3. Set your preferred heating and cooling temperatures.
4. Enable Auto-Schedule to allow the thermostat to learn from your manual adjustments over the next one to two weeks.
5. Enable Home/Away Assist for automatic energy savings when you leave the house.
6. Complete the setup in the Google Home app to enable remote control and energy monitoring.

Tips for Best Performance

• During the first two weeks, manually adjust the thermostat to your preferred temperatures at various times of day. The learning algorithm uses this input to build your automatic schedule.
• Use the Nest Leaf icon as a guide — it appears when you choose an energy-efficient temperature.
• Check the Energy History in the app monthly to see how much energy you are saving.
• If the thermostat frequently shows low battery warnings, install a C-wire or Nest Power Connector for reliable power.