Sensi Lite Smart Thermostat

Connect to Comfort

Models: 1F76U-22WFB series, ST25 series

Version: February 2023

Downloading the App and Creating an Account

You Will Need

Wi-Fi Network Name/SSID (2.4GHz network)
Wi-Fi Network Password
Screwdriver
Hardware in Sensi Lite smart thermostat packaging

Download the Sensi App

The Sensi Lite smart thermostat is a Wi-Fi enabled device. To install and configure your thermostat correctly, you must use the Sensi app. Download the Sensi app to your smartphone or tablet. It is a free download.

Scan the QR code to download the Sensi app.

Create an Account

When you download the Sensi app, you will be prompted to create an account. This is required to access your thermostat remotely and use all the features Sensi offers. Use a valid email address and a password of your choosing to create an account. Remember this email address and password. Your Sensi thermostat will be linked to this email address once it is registered.

Installing the Sensi Thermostat

Step 1: Add your thermostat to the Sensi app

Once you have downloaded the Sensi app and created an account, you are ready to install the thermostat to your wall and connect it to Wi-Fi. If there are no registered thermostats, tap the plus (+) sign to add a thermostat.

First, choose which thermostat you purchased. The Sensi Lite smart thermostat option is for the following model numbers:

ST25 series
1F76U-22WFB series

Note: You can check your model number on the back of the thermostat cover.

Step 2: Is your Sensi thermostat already on your wall?

New Installation

After choosing your Sensi model, tap New Installation. Next, select whether your thermostat Is Currently Mounted or Not Mounted on the wall.

Not Mounted

This option walks you through a full step-by-step installation process. You will identify which wires are on your original thermostat, how to label them for Sensi, how to connect your wires and how to connect to Wi-Fi. If you did not have this thermostat professionally installed, choose this option. It will ensure that your thermostat is properly wired and configured to work with your HVAC system.

Is Currently Mounted

This option asks you to identify the wires already installed on your Sensi Lite to ensure that your HVAC settings are correct and connects you to Wi-Fi. If you had a professional technician install your thermostat, choose this option and skip to STEP 5.

Pro Tip: If you are DIYing your installation, always choose Not Mounted to make sure your thermostat is wired and configured correctly.

Step 3: Remove the old thermostat from your wall

Gather Tools and Package Contents

Gather all the necessary tools for installation.

Turn Off Power

Turn off the power to your heating and air conditioning system before handling your thermostat wires.

Remove Old Thermostat Cover

Remove the cover using a screwdriver or by pushing the pressure latch. Some covers pull off while others need to be released using a screwdriver.

Photograph Your Wiring

THIS IS IMPORTANT. The Sensi app will prompt you to take a picture of your existing thermostat and old wiring in case you need it later. This can be helpful for troubleshooting with our technical support team, if necessary. The picture you take will be saved to your camera roll or photo gallery.

Throw Away Any Jumper Wires

Sensi has a jumper wire built into it, and you will not need any jumper wires from your old unit.

Choose Wire Terminals

Choose the terminal labels that have wires attached to them on your old thermostat. The app will tell you if you have a valid configuration. If you are getting an invalid configuration message you can learn more about compatibility at sensi.emerson.com/system.

Diagram showing thermostat terminals R, O/B, Y, G, W/E, C, RH, W1, Y1, RC, W/E, Y2, B, C, W/2, L, O/B, X, E, AUX, Other.

Diagram showing wire labels for old thermostat and Sensi.

Diagram showing how to pick wires.

Diagram showing jumper wires and how to remove them.

Furnace Type

Select what type of system you have.

Label Your Wires

Before you disconnect your wires, label your wires using the label stickers provided one wire at a time.

Diagram showing wire labels for old thermostat and Sensi.

Note: Your labels may not match; that's okay! For example, you may have a W wire; you can apply the W/E sticker.

Disconnect Wires and Remove Base

After all of your wires are labeled, remove the old thermostat base from the wall.

Step 4: Secure your new thermostat base to the wall and connect wires

Install Sensi Base

Use the mounting screws provided and secure the Sensi base to the wall.

Diagram showing how to install the new thermostat base.

Connect the Wires

Once the Sensi base is mounted and secured on the wall, insert the wires into the corresponding terminals, then tighten the screw.

Diagram showing how to connect wires to the terminals.

Step 5: Scan QR code and attach thermostat cover

Scan QR Code

On the back of the thermostat or in the Welcome/Get Started insert found in the box, you will find the QR Code to connect the thermostat to your Wi-Fi network. Scan this code. You will need to allow Sensi access to Bluetooth to connect properly.

If you're having trouble scanning, tap Use PIN to manually enter the code located under the QR code.

Diagram showing the QR code on the back of the thermostat or on the Get Started card.

Install Batteries and Attach Thermostat Cover

Install the two provided AAA batteries and push the thermostat cover onto the base.

Diagram showing how to attach the thermostat cover to the baseplate.

Turn On Power

Turn the power to your heating and air conditioning system back on.

Step 6: Connecting to Wi-Fi and registering your thermostat

Wi-Fi Setup

On the thermostat, press and hold the Mode Button for four seconds. You will see the setup and Wi-Fi icons appear.

Diagram showing Wi-Fi setup on the thermostat.

Select Your Wi-Fi Network

In the mobile app, select your home Wi-Fi network and then enter your home Wi-Fi network password.

Pro Tip: Sensi is only compatible with 2.4GHz networks. If your network does not show up in the list, it is either hidden or not compatible with Sensi.

Diagram showing how to select a Wi-Fi network in the app.

Name Thermostat

You can select a name or choose a custom name for your thermostat. Press Next to continue.

Diagram showing how to name the thermostat in the app.

Register Thermostat

After successfully connecting Sensi, the app will prompt you to register the thermostat. You can either choose the Locate Me option or fill in your street address, city, state, ZIP code, country and time zone manually. Press Next to continue.

Diagram showing how to register the thermostat in the app.

Contractor Information (Optional)

If a contractor professionally installed your thermostat and is registered as a Sensi partner, they have the option to input their phone number here. If there is not a registered number available, simply hit Next to continue.

Diagram showing the contractor information screen.

Start Using Sensi

Congratulations on successfully installing Sensi. Press Start Using Sensi to open the main screen of the app.

Troubleshooting

Why isn't my heating/cooling turning on?

Ensure that there is power to your HVAC system and there is no error code on your control board indicating a system issue.
If there is an error code or no power to your system, contact an HVAC professional to service your equipment.
Reset breakers.
Make sure the furnace/air handler door compartments are securely screwed down and closed. If the door panels are not secure, the system will not start.
Secure wire connections.
Ensure the thermostat is wired correctly by following the instructions in the Sensi app.
You can also try to reinstall your original thermostat to make sure there is not an HVAC system issue that is preventing the system from turning on. If your heating/cooling doesn't come on with the original thermostat, you may need to contact a professional technician to service your equipment.

Connecting to Wi-Fi troubleshooting

Make sure the Sensi app is up-to-date and running the latest version available in your app store.
Reboot your smartphone.
Reboot your router by unplugging it from the wall for a few minutes and then plugging it back in.
Make sure Bluetooth is turned on in your phone settings and is allowed in the Sensi app permissions.
Make sure Location access is turned on in your phone settings and is allowed in the Sensi app permissions.
Try another smartphone or tablet. Simply download the Sensi app and sign into the app using the email address and password you used when you created your account.

Reconnecting to Wi-Fi

If you replaced your router or changed your Wi-Fi network password, you will need to reconnect your thermostat to Wi-Fi. This process is different depending on what smart device you are using. Please see our support article for more information on how to reconnect: sensi.emerson.com/en-us/support/reconnecting-sensi-thermostat-to-wifi

Notes

HVAC configuration menu

If you want to check that your thermostat's HVAC settings were configured correctly or you're experiencing a system issue, refer to the chart for equipment descriptions and options. Learn more about how to properly configure your thermostat here: sensi.emerson.com/en-us/support/how-do-i-configure-my-thermostat

Table showing Configuration Menu Items Reference: Menu Item, Description, Options for Outdoor Equipment, Indoor Equipment, Reversing Valve or Multistage Position, Multistage Equipment.

Accessing your Sensi thermostat from other devices

When you log into your Sensi account with your email address and password, the app will be able to control all the thermostats registered to your Sensi account.

If you give someone else your email address and the password to your Sensi account, they will be able to log in and control any thermostats registered to that account. You can change your email address and password from inside the app. Be aware of this when giving out your information. There is no limit to the number of devices that can access the thermostat.

For iOS: Tap the person icon in the upper right corner.

For Android: Tap the three dots in the upper right corner.

Forgot password

If you forget the password to your Sensi account, click on Forgot Password on the login screen of the Sensi app. A temporary password will be sent to the email address that you use to log in.

Installing multiple thermostats

If you are installing more than one thermostat, follow the same installation process in the Sensi app. Once you have one thermostat installed, open the Sensi app on your phone. At the main screen, press the + sign to add another thermostat to your account.

Accessing account information

You can use the Account area to access your email preferences and change your account information and the email address associated with your Sensi.

Technical support

For problems installing your Sensi thermostat, visit our support site. We have a vast collection of troubleshooting articles aimed at helping you install Sensi and using its features. We also have a support team available to help assist you.

sensihelp.com

(888) 605.7131

Wiring Diagrams

Conventional Single-Stage or Multi-Stage Systems (No Heat Pump)

Diagram showing thermostat wiring for conventional systems.

System configuration labels: R, O/B*, Y, G, W/E, C

Terminal descriptions:

R: 24VAC power from HVAC system
O/B*: Heat pump changeover (reversing valve) connection (configure as O or B in the installer menu). Multi-stage not available for heat pump configurations.
Y: 1st-stage heat and cool (compressor)
G: Indoor blower (fan)
W/E: 1st-stage auxiliary/emergency heat (2nd-stage heat)
C: Common wire** (24V)

*System only capable of multi-stage heating or multi-stage cooling, not both.

**Common connection required on heat-only, cool-only or heat pump systems.

Diagram showing 24VAC power connections (HOT/NEUTRAL) and phased relationship dots.

Heat Pump Systems

Diagram showing thermostat wiring for heat pump systems.