Sensi Smart Thermostat Installation Guide

The Sensi Smart Thermostat is a Wi-Fi-enabled thermostat designed to help users control their heating and cooling system through the Sensi mobile app. This installation guide applies to Sensi Smart Thermostat models 1F87U-42WF and ST55.

The thermostat setup is handled through the Sensi app, which guides users through installation, wiring, HVAC system selection, Wi-Fi setup, thermostat registration, and account access. The guide is useful for both DIY users and homeowners whose thermostat was already installed by a professional.

Supported Models

Product	Model
Sensi Smart Thermostat	1F87U-42WF
Sensi Smart Thermostat	ST55

The model number can be found on the back of the thermostat cover.

What You Need Before Installation

Before starting the installation, prepare the following:

Requirement	Purpose
2.4GHz Wi-Fi network name/SSID	Required for Wi-Fi connection
Wi-Fi password	Needed during app setup
Screwdriver	Used to remove the old thermostat and secure wiring
Included Sensi hardware	Used to mount and install the thermostat
Sensi app	Required for guided setup and configuration

The thermostat must be connected to a 2.4GHz Wi-Fi network. The app-based installation may not work properly if the home network is hidden, incompatible, or using the wrong band.

Downloading the Sensi App

The Sensi Smart Thermostat must be installed and configured using the Sensi app. The app is free and available for smartphones and tablets through the App Store and Google Play.

To begin:

1. Download the Sensi app.
2. Open the app.
3. Create a Sensi account.
4. Use a valid email address and password.
5. Keep the login details safe, because the thermostat will be linked to this account after registration.

The manual notes that the “Install a device” option is only for HomeKit installation. Users may lose available features if they do not create a Sensi account.

Creating a Sensi Account

A Sensi account is required to access the thermostat remotely and use Sensi features. After downloading the app, users are prompted to create an account with an email address and password.

If the password is forgotten later, tap Forgot Password on the Sensi app login screen. A temporary password will be sent to the email address used for the account.

Parts and Key Components

The manual focuses on installation and wiring rather than a full product parts diagram. However, the setup process references these important components:

Component	Function
Thermostat cover/front display	Main thermostat control and display area
Thermostat base/sub-base	Mounts to the wall and holds wiring terminals
Wire terminals	Connect HVAC system wires
Built-in jumper	Replaces old jumper wires from the previous thermostat
RC/RH internal jumper	Used for transformer wiring; may need clipping on two-transformer systems
Mounting screws	Secure the thermostat base to the wall
Menu button	Used during Wi-Fi setup
Mode button	Used to start Wi-Fi setup
L terminal	Heat pump L terminal connection
Y2/W2 terminals	Used for second-stage cooling/heating or accessories depending on setup

The wiring diagram on page 10 shows the terminal layout for conventional and heat pump systems.

How to Install the Sensi Smart Thermostat

Step 1: Add the Thermostat to the Sensi App

Once the Sensi app is downloaded and the account is created:

1. Open the Sensi app.
2. Tap the plus (+) sign.
3. Choose the Sensi Smart Thermostat option.
4. Select the correct model series.

The app will then begin the guided installation process.

Step 2: Choose Installation Type

The app asks whether the thermostat is already mounted on the wall.

Not Mounted

Choose Not Mounted for a DIY installation. This path walks through the complete setup process, including wire identification, wire labeling, wiring, HVAC configuration, and Wi-Fi connection.

The manual recommends this option for DIY users because it helps make sure the thermostat is wired and configured correctly.

Is Currently Mounted

Choose Is Currently Mounted if a professional technician already installed the thermostat. This option asks users to identify the wires already connected to the Sensi base, confirm system settings, and continue to Wi-Fi setup.

Step 3: Remove the Old Thermostat

Before handling thermostat wires, turn off power to the heating and air conditioning system.

Then follow these steps:

1. Gather the required tools and package contents.
2. Turn off HVAC power.
3. Remove the old thermostat cover.
4. Take a clear photo of the old wiring.
5. Throw away old jumper wires.
6. Select the wire terminals that had wires attached on the old thermostat.
7. Let the app confirm whether the wiring configuration is valid.
8. Select the furnace type.
9. Label each wire using the provided wire stickers.
10. Disconnect the wires.
11. Remove the old thermostat base from the wall.

The wiring photo is important because it can help if troubleshooting or support is needed later.

Step 4: Secure the Sensi Base to the Wall

After removing the old thermostat base, install the new Sensi base.

Use the provided mounting screws to secure the base to the wall. Make sure the base is positioned correctly, the wires are accessible, and the wire labels are still visible before connecting them.

Step 5a: Connect Wiring for a New Installation

For a Not Mounted installation:

1. Insert each labeled wire into the correct terminal.
2. Push the wire into the terminal slot.
3. Use a screwdriver to secure each wire.
4. Push the front display onto the thermostat base.
5. Turn system power back on.

The manual explains that Sensi has a built-in jumper, so old jumper wires from the previous thermostat are not needed.

Step 5b: Setup for an Already Mounted Thermostat

For an Is Currently Mounted setup:

1. Turn off power to the heating and cooling system.
2. Pull the thermostat cover straight toward you with both hands.
3. Identify which terminal labels have wires attached.
4. Select the furnace type.
5. Push the thermostat cover back onto the base.
6. Turn system power back on.

This setup path helps confirm that the thermostat is configured correctly for the HVAC system type.

Step 6: Connect the Sensi Smart Thermostat to Wi-Fi

After wiring and installation, connect the thermostat to Wi-Fi.

On the thermostat:

1. Press Menu.
2. Press Mode.
3. Wait for the Wi-Fi icon in the upper-left corner to flash.
4. Look for the display code in the middle of the thermostat.

The thermostat may show 00, 11, or 22. This code identifies the Sensi version and helps the app guide the correct connection process.

Then follow the Sensi app instructions to connect the thermostat to the home Wi-Fi network. The Wi-Fi setup process may vary based on the phone operating system, Sensi app version, and thermostat version.

For iPhone users, the manual notes that HomeKit-related errors may require checking Sensi app permissions and allowing access to Home Data.

Naming and Registering the Thermostat

After the thermostat connects to Wi-Fi, the app prompts users to name and register it.

Registration may include:

Information	Purpose
Thermostat name	Helps identify the device in the app
Street address	Used for thermostat location
City, state, ZIP code	Helps complete registration
Country	Location setting
Time zone	Used for correct scheduling and time display
Contractor information	Optional, if a Sensi partner installed the thermostat

Users can choose Locate Me or manually enter the address information. After setup, tap Start Using Sensi to open the app’s main screen.

HVAC Configuration Menu

The Sensi Smart Thermostat includes a physical thermostat configuration menu for checking or adjusting HVAC settings.

Display Code / Menu Item	Default	Options
Wireless Setup	—	Connect
Fahrenheit or Celsius	F	F, C
Outdoor Equipment Configuration	AC2	AC1, AC2, HP1, HP2, AC0
Indoor Equipment Configuration	EL2	EL1, EL2, GA1, GA2, Fan
Reversing Valve Position	O	O, B
Circulating Fan	OFF	Off, 10%–100% in 5% increments
Humidification Add Accessory	OFF	Off, On
Humidification Set Point	OFF	Off, 5%–50% in 5% increments
Dehumidification Add Accessory	Od	Od, Oc
Dehumidification Set Point	OFF	Off, 40%–95% in 5% increments
Wireless Radio	ON	Off, On

For heat pumps, the reversing valve can be set to O or B. The O setting is commonly used when the reversing valve energizes in cooling, while B is used by some systems that energize in heating.

Supported HVAC System Types

Conventional Single-Stage and Multi-Stage Systems

The wiring diagram on page 10 covers conventional systems without a heat pump.

Terminal	Function
RC	Power for cooling, 24V
RH	Power for heating, 24V
C	Common wire, 24V
Y	First-stage cooling
Y2	Second-stage cooling or humidifier if configured
W/E	First-stage heat
W2	Second-stage heat or dehumidifier if configured
G	Indoor blower fan
O/B	Heat pump changeover, zone panel, or 3-wire hot water zone valve connection
L	Heat pump L terminal connection

For two-transformer systems with separate RC and RH wires, the internal RC/RH jumper on the back of the thermostat should be clipped.

Heat Pump Systems

The heat pump wiring diagram on page 10 covers single-stage and multi-stage heat pump systems.

Terminal	Function
RC	Power for cooling, 24V
RH	Power for heating, 24V
C	Common wire, 24V
Y	First-stage heat and cool compressor
Y2	Second-stage heat and cool compressor
W/E	First-stage auxiliary/emergency heat
W2	Additional auxiliary/emergency heat or dehumidifier depending on setup
G	Indoor blower fan
O/B	Heat pump reversing valve
L	Heat pump L terminal connection

The thermostat includes an internal jumper between RC and RH on the back of the unit.

Wi-Fi Troubleshooting

If the thermostat does not connect to Wi-Fi, try the following:

Issue	Recommended Fix
Sensi app is outdated	Update the app from the app store
Phone issue	Reboot the smartphone
Router issue	Unplug the router for a few minutes, then plug it back in
iPhone permission issue	Turn on Keychain and allow Home Data
Location issue	Turn on Location services
App permissions issue	Allow Location and Nearby Devices
Android network switching	Turn off “Switch to mobile data,” “Smart Network Switch,” or “Avoid poor connections”
Setup instability	Turn off mobile data during setup
Device-specific issue	Try another smartphone or tablet

The thermostat setup may fail if the phone disconnects from Wi-Fi during installation, especially on Android devices that automatically switch to mobile data.

Reconnecting to Wi-Fi

If the router is replaced or the Wi-Fi password changes, the thermostat must be reconnected to Wi-Fi.

The reconnection process depends on the smart device being used. The manual directs users to Sensi’s reconnection support article for detailed steps.

Heating or Cooling Troubleshooting

If the system does not heat or cool correctly, check the HVAC configuration menu on the thermostat.

Common causes include:

Possible Cause	What to Check
Incorrect outdoor equipment setting	Confirm AC or heat pump configuration
Incorrect indoor equipment setting	Confirm gas, electric, or fan setup
Wrong reversing valve setting	Check O/B heat pump setting
Loose wiring	Confirm all wires are secure
Wrong terminal selection	Compare wiring with the app and old wiring photo
Accessory misconfiguration	Check humidifier/dehumidifier settings
Power issue	Confirm HVAC power and breakers

The app and physical thermostat configuration menu should match the actual HVAC system.

Accessing the Thermostat from Other Devices

Any device logged into the same Sensi account can control all thermostats registered to that account.

The manual warns users to be careful when sharing the Sensi account email and password. Anyone with those login details can access and control registered thermostats. There is no stated limit to the number of devices that can access the thermostat.

Installing Multiple Sensi Smart Thermostats

To install more than one thermostat:

1. Install the first thermostat using the Sensi app.
2. Open the app main screen.
3. Tap the plus (+) sign.
4. Add the next thermostat.
5. Repeat the installation process.

Each thermostat should be added and registered separately.

Account Settings and Password Help

Users can access account settings inside the Sensi app to update email preferences, account details, and the email address connected to the thermostat.

Device	How to Access Account Area
iOS	Tap the person icon in the upper-right corner
Android	Tap the three dots in the upper-right corner

For a forgotten password, tap Forgot Password on the login screen. A temporary password will be sent to the registered email address.

Technical Support

For installation problems, setup issues, Wi-Fi connection problems, and thermostat feature help, users can contact Sensi support.

Support Option	Details
Support website	sensihelp.com
Phone support	(888) 605-7131
Compatibility help	sensi.copeland.com/en-us/compatibility
Wi-Fi reconnection support	sensi.copeland.com/en-us/support/reconnecting-sensi-thermostat-to-wifi

Official Installation Guide (PDF)