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Document DEVICE REPORTehb l40 2503
L40
Residential Control System Programmable Smart Wi-Fi Thermostat RESIDENTIAL PRODUCT SPECIFICATIONS (EHB)
The L40 is a Smart Wi-Fi, electronic 7-day, universal, programmable, touchscreen thermostat. · LCD display with backlight shows the current and set
temperature, and system status (operating mode and schedules) · Touchscreen interaction · Ergonomic design · Smooth Setback Recovery starts system early to achieve setpoint at start of program period · Compressor short-cycle protection (5 minutes) · Real-time clock keeps time during power failures and automatically updates to daylight savings · Maintenance reminders let user know when to service or replace filters, PureAir® metal insert, humidifier pads, ultraviolet lamps, ventilation and ventilation filter · Up to four separate schedules are available plus Schedule IQTM · One-Touch Away Mode - A quick and easy way to set the cooling and heating setpoints while away · Permanent memory storage of settings · Wallplate furnished
APPROVALS · ENERGY STAR® certified · Factory preset program settings conform to EPA
ENERGY STAR® recommended setpoints
APPLICATIONS · Fully programmable thermostat provides universal
system compatibility, precise comfort control and easy programmability · Provides temperature control for gas, electric and heat pumps for single-stage heating or cooling systems (including dual-fuel operation)
HOME AUTOMATION · Amazon® Alexa-enabled · Works with Google Assistant · Works with Control4® and Building36® integration
WARRANTY · Limited five years in residential applications NOTE - Refer to Lennox® Basic Limited Warranty at www.
Lennox.com for additional details.

CONTROLS
1 Heat / 1 Cool Universal

Control temperature, fan operation, set programs/ schedules and set Away mode in the Lennox® Home App.

Dallas Home

Temp

Status My Home

Feels Like
72 60%

Heat to

Cool to

68

75

Away

Weather

Connected to System Name Service Center
Notifications Equipment Settings Information Tests Diagnostics Installation Report Refrigerant Charge Disconnect from System Name

All thermostat commissioning and settings are made in the Lennox® Smart Tech App.

CONTENTS
Commissioning - Initial Setup (Thermostat) .  .  .  .  .  .  12 Dealer Service Center - Installer Settings (Thermostat)13 Home Automation .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  3 Homeowner Settings  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  4 Mobile Apps (Homeowner/Installer)  .  .  .  .  .  .  .  .  .  .  . 2 Specifications  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 16

Form Number 210878 | March 2025 Supersedes all previous versions

MOBILE APPS (HOMEOWNER/INSTALLER) LENNOX HOME (Homeowner)

LENNOX SMART TECH (Installer)

Dallas Home

Temp

Status My Home

The free Lennox Home App is available for use on smartphones.
Control cooling/heating temperatures, fan operation, set programs/ schedules and set Away mode for multiple locations.

Feels Like
72 60%

Heat to

Cool to

68

75

Away

Weather

LENNOX PROS APP (Installer)

Connected to System Name
Service Center Notifications

Equipment Settings

Allows the installer to commission the system and remotely turn the system on and off during setup or service call from a smartphone.
Alerts and Notifications sent to Dealer to notify when servicing or maintenance is required.

Information Tests Diagnostics Installation Report Refrigerant Charge
Disconnect from System Name

Share avanced diagnostics with the Dealer to aid in servicing and troubleshooting.

Allows quick connection to the thermostat via Bluetooth for easier system configuration changes via a Smartphone.

· Equipment Configuration Profile (ECP):

· Allows dealers to create unique equipment profiles specific to products sold at their dealership

· Can be imported into the homeowner's smart thermostat reducing setup times

LennoxPROs mobile application has all the information HVAC Professionals and businesses need in one place. · Product Catalog · Residential/Commercial products · Parts and Supplies · Clearance Center · Real-Time Product Availability · Technical Tools · AHRI Residential Match-up Tool · OEM Repair Parts · Technical Documents · Sales Tools · Marketing Brochures · Commercial Quick Quote · Warranty Tools · Warranty Lookup · Training Center · My Learning
Apple, the Apple logo, iPhone and iPad are trademarks of Apple Inc. registered in the US and other countries. Android is a trademark of Google Inc. Use of this trademark is subject to Google permission.
L40 Smart Wi-Fi Thermostat / Page 2

HOME AUTOMATION Amazon® Alexa The L40 Smart Thermostat is an Amazon® Alexa-enabled, smarthome-compatible thermostat. Allows the homeowner to tell Alexa to control system mode and heating cooling setpoints. Works in conjunction with the Amazon Alexa app (click icon):
See User Guide for additional information about device setup and available voice commands.
Amazon's trademark is used under license from Amazon.com, Inc. or its affiliates.

Google Assistant Control basic functions of the L40 thermostat using Google Assistant. Download the Google Home app from Google Play or the App StoreTM on a compatible phone or tablet, then follow the on-screen steps to finish setup. Once you have added the thermostat to your Google Home app install the Google Assistant app (Android and IOS) to enable voice control. NOTE - The Google Assistant app may already be installed
on the Android device. For additional information please visit the Lennox® Support Website for Google Assistant Integration.
Google and the Google logo are registered trademarks of Google LLC, used with permission.

Control4® Smart Home | Operating System Control4 is a leading control and automation platform which works with thousands of smart devices integrating audio, video, lighting, security, intercom, and climate control into a seamless customer experience
Control4 gives the customer an easy-to-use interface to control the Lennox® L40 thermostat.
Settings include:
· Display all systems in the home and select a system
· Display all zones in the system and select a zone
· Turn system or zones on or off
· Change manual modes (heat, cool, off)
· Change heating/cooling setpoints for each zone/system
· Change fan mode (on, auto, circulate)
For additional information please visit the Support Website for Control4 Integration.

Building36® Practical Home Automation Building36® is a leading control and automation company that delivers next-generation smart home solutions which work with thousands of smart devices, integrating control for HVAC, water, video, lighting/appliance and security into one location
Building36® gives the customer an easy-touse interface via the Building36 Dashboard or the Building36 Home Mobile App to control the Lennox' L40 thermostat
Settings include:
· Display all systems in the home and select a system
· Display all zones in the system and select a zone
· Turn system or zones on or off
· Change manual modes (heat, cool, off)
· Change heating/cooling setpoints for each zone/system
· Change fan mode (on, auto, circulate)

NOTE - For integration with Lennox® L40 Thermostats, the customer must contact their Control4 dealer directly to download and install the necessary driver for their operating system.
Control4® is a registered trademark of Control4 Corporation. All rights reserved.

For additional information please visit https://building36. com
BUILDING36® is a registered service mark of Building36. All rights reserved.

L40 Smart Wi-Fi Thermostat / Page 3

HOMEOWNER SETTINGS HOME SCREEN

Notes
All thermostat settings can also be made in the Lennox® Home App. If screen is dark, touch screen to turn on the backlight.

Temperature Settings Large display of current inside temperature (°F or °C) Heating and Cooling Setpoint Indicators on the round temperature band Current cooling setpoint temperature Button (right-side)
Current heating setpoint temperature Button (left-side)
Menu Button Away Button
Configuration Button
Notifications Button Mode Icons (Split Systems)
Heat / Cool Heat Only Cool Only Emergency Heat (emergency heat operating as main heating source) Off

Touching the heat or cool setpoint indicators on the round temperature band, or touching the heating or cooling buttons displays the heat or cool menu screens (see page 6). Both heating and cooling setpoint indicators on the round temperature band and the heating or cooling setpoint buttons are displayed if System is set to Heat/Cool. Indicator mark on the round band marks the temperature setting. Various animated icons appear above the current temperature depending on system operation..
Touch to display Menu screen (see page 7).
Touch to display Away Mode screen (see page 6).
Animated icons also appear here for configuration, maintenance notification, Wi-fi status, peak monitoring, or upcoming functions.
Only displayed if there are active notifications Touch to display any active notifications.
Touch the Menu button on the home screen, touch Mode to display the Mode Screen. Animated versions of these icons are also displayed on the Home screen above the actual temperature to indicate current system operation. The Off icon is displayed below the actual temperature if the system is not running. Touch the Off icon to display the Mode Screen directly.

L40 Smart Wi-Fi Thermostat / Page 4

HOMEOWNER SETTINGS HOME SCREEN (Continued) Fan Status Icons (Split Systems)
Fan On Fan Auto Fan Circulate
Miscellaneous Icons System Tests Schedule Hold Service Urgent Peak Monitoring

Notes
Touch the Menu button on the home screen, touch Fan to display the Fan Screen.
System Tests is displayed when system is configured for different equipment. Schedule Hold is displayed when a current schedule override is in effect. Service Urgent is displayed if there is a critical issue with the system. Peak Monitoring allows the utility company to control the energy savings time period. You can select cancel to exit this mode. By canceling homeowner is opting out of the current active energy savings events. (Also see ???) Peak Monitoring Registration is set up in the Lennox® Home App.

L40 Smart Wi-Fi Thermostat / Page 5

HOMEOWNER SETTINGS HEAT MENU SCREEN
Heating setpoint display Heating Setpoint Indicator on the round temperature band Plus (+) and Minus (­) buttons Home button (return to Home Screen) COOL MENU SCREEN
Cooling setpoint display Cooling Setpoint Indicator on the round temperature band Plus (+) and Minus (­) buttons Home button (return to Home Screen) AWAY SCREEN
Set heating or cooling setpoints during unoccupied periods Heating and Cooling Setpoint Indicators on the round temperature band Current away cooling setpoint temperature Button (right) Current away heating setpoint temperature Button (left) Cancel Away Mode Button
L40 Smart Wi-Fi Thermostat / Page 6

Notes
On the Home Screen, touching the heat setpoint indicators on the round temperature band, or touching the Plus (+) and Minus (­) buttons displays the heat menu screen.
Touch and move the red heat setpoint indicator on the round temperature band, or touch the plus or minus buttons to change the heating setpoint in one degree increments. Adjustable 60 to 87°F.
A wider setpoint range (40 to 99°F) can be set in the Lennox®Home App.
During a scheduled time period, touching either the setpoint indicator on the temperature band or the heat-to button will initiate a schedule hold (see page 8).
Notes
On the Home Screen, touching the cool setpoint indicators on the round temperature band, or touching the Plus (+) and Minus (­) buttons displays the cool menu screen.
Touch and move the blue cool setpoint indicator on the round temperature band, or touch the plus or minus buttons to change the cooling setpoint in one degree increments. Adjustable 63 to 90°F.
A wider setpoint range (40 to 99°F) can be set in the Lennox®Home App.
During a scheduled time period, touching either the setpoint indicator on the temperature band or the cool-to button will initiate a schedule hold (see page 8).
Notes

Touch the Away button Away setpoint screen.

to access the

Touch the heat or cool setpoint indicators on the round temperature band, or touch the heating or cooling buttons to change the away setpoints.

Touch Cancel to end away mode and return to current system operation.

Away setpoints are adjustable in the Lennox® Home App: 40 to 87°F Heating 60 to 90°FCooling

HOMEOWNER SETTINGS MENU SCREEN

Notes

Notifications - Displays system operating and service reminder messages (see page 7)
User Settings (see page 8) Mode (see page 8) Schedule (see page 9) Fan (see page 9) Wi-Fi (see page 9) Thermostat Settings (see page 9) Advanced Settings (see page 13) NOTIFICATIONS SCREEN

Touch the Menu button on the home screen to display the Menu screen.

Touch each item to display the selected screen. Scroll down to see all menu items.

Touch the Home Home Screen.

button to return to the

Notes

Critical (Red Alert) - Displays information that service is required for a major system component as soon as possible
Warnings (Orange Alert) - Displays information about system operation
Reminders (Yellow Alert) - Displays required maintenance information (filter replacement, humidifier pad replacement, UV light replacement)
Info (Blue Alert) - Displays information about installer access, Wi-Fi status, new devices found, software updates and additional useful information and tips to operate the system efficiently

Number of notifications will be displayed over the Menu Button on the Home Screen. Touch the Menu button to go to Notifications.
Touch the > to display the complete message for each notification.
Alerts homeowner of critical and required service or maintenance issues.
Notification settings (Filter replacement time, etc.) are set in the Lennox® Home App.

L40 Smart Wi-Fi Thermostat / Page 7

HOMEOWNER SETTINGS USER SETTINGS SCREEN
Account Configure Thermostat Button Move Out (Yes/No) Home Help and Support MODE SCREEN (Split Systems)
Heat/Cool Button Heat Only Button Cool Only Button Emergency Heat Button (heat pump systems only) Off Button SCHEDULE SCREEN
L40 Smart Wi-Fi Thermostat / Page 8

Notes
If no account is set up touch > touch the Configure Thermostat button to begin setting up account. If an account is set up the homeowner's e-mail address will be displayed. Home displays the current home name and address that the thermostat is associated with. Move Out signs out of the current account and removes the thermostat from the current account. To view more account information or to change the password use the Lennox® Home App.
Notes
Touch Mode on Menu screen to access screen.

Touch each button to set the mode of operation.

Touch the Home button Home Screen.

to return to the

Notes

Touch to start a schedule.
Schedules are modified in the Lennox® Home App.

HOMEOWNER SETTINGS FAN SCREEN (Split Systems)

Setting

Default

Notes

Touch the Menu button

on the home

screen to display menu. Touch the Fan

menu to display the Fan screen.

Touch the Home button Home Screen.

to return to the

On Button Auto Button Circulate Button WI-FI SCREEN
Current Active Network Button Change Network THERMOSTAT SETTINGS SCREEN

9 to 27 minutes 21 minutes

Touch each button to set the fan operation.
Fan runtime adjustment is selected in the Lennox® Home App.
Notes
A graphical representation of the home network showing the connection status from the Thermostat to the Internet to the Lennox server.
Touch the > to see current network SSID, IPAddress, Security level and RSSI. Touch the i button for additional information about a particular network (name, SSID, security, RSSI, etc.) available on the Lennox® Home App. Touch Change Network displays thermostat connectivity through the Lennox® Home App. A red "X" means that there is an issue with a connection point that must be resolved.
Notes

System Name (not shown) Thermostat Name About Thermostat (see page 10)

System Name is set in the Lennox® Home App.
Thermostat Name is set in the Lennox® Home App.

L40 Smart Wi-Fi Thermostat / Page 9

HOMEOWNER SETTINGS ABOUT THERMOSTAT SCREEN
Thermostat Information (see page 10) Software Update (see page 10) Software Revision (see page 11) THERMOSTAT INFORMATION SCREEN

Notes - - -
Notes

Model Number Serial Number Hardware Revision MAC Address SOFTWARE UPDATE SCREEN

Setting

Default

- - Notes

Automatic Updates Check for Updates Now button

On/Off

On

Click the Check for Updates Now button to manually download and install any available software updates.

L40 Smart Wi-Fi Thermostat / Page 10

HOMEOWNER SETTINGS SOFTWARE REVISION SCREEN

Notes

Software Revision Number Last Updated Last Update Notes ADVANCED SETTINGS SCREEN

Setting

View Support Service Control Center - See page 13

Restart

Restart Thermostat

- - -
Touching View Support Service Control Center displays a warning "The following screens are intended for use by qualified Lennox equipment installers only.". Restart Thermostat restarts the system without affecting settings.

L40 Smart Wi-Fi Thermostat / Page 11

COMMISSIONING - INITIAL SETUP (THERMOSTAT)

After power is applied to the thermostat for the first time it displays the Lennox® "splash screen".
The Installer is then presented with the several Setup Screens to configure the system prior to operation.
NOTE - Full thermostat and system configuration is set in the Lennox® Smart Tech Thermostat App (recommended). See page 2.

MENU Language Setup Route Dealer Information Date and Time
Temperature Indoor Unit Outdoor Unit
Reminder

SETTING (default is BOLD) English Español Français Smart Tech App (Recommended)

L40 Thermostat

Dealer ID Letter Dealer ID Number Date Time Time Zone
Daylight Savings Temperature Unit Not Installed 1 Stage Electric No Heat 1 Stage Electric 1 Stage Gas Not Installed 1 Stage AC Unit 1 Stage HP Unit Outdoor Unit Capacity Balance Points Replace Filter 1 Replace Filter 2 Maintenance Reminder

Atlantic Eastern Central Mountain Pacific Alaska Hawaii Samoa Chamorro (Guam) On or Off °F or °C
18 to 60 kBtu (36 kBtu) Disabled or Enabled 3, 6, 12, 24 months, disabled

Notes: - - -
All information is added using the app on a mobile device. Partial information is added on the thermostat. Scroll to select letter. Use keypad to input number.
Scroll to set date and time. NOTE - Date and Time is automatically set when connected to the Internet.
- - -
- - -
- - Adjustable 18 to 60 kBtu Heat Pump
- - -

L40 Smart Wi-Fi Thermostat / Page 12

DEALER SERVICE CENTER - INSTALLER SETTINGS (THERMOSTAT)
NOTE - INSTALLER SETTINGS SHOWN ARE ON THE THERMOSTAT ONLY! ADDITIONAL SETTINGS ARE AVAILABLE ON THE LENNOX® SMART TECH APP. SEE page 2.

CONNECT TO MOBILE APP Discover

Provides access to the installer for viewing and performing various functions. · Connect to Mobile App · Equipment Settings · Notifications · Installation Report · Information · Exit Dealer Service Center
Start Button

Stop Broadcasting Button

EQUIPMENT SETTINGS

THERMOSTAT SETTING (default is BOLD)

About

Product Type

Language Support

Equipment Type Name

Control Software Revision

Control Model Number

Control Serial Number

Control Hardware Revision

Protocol Revision Number

Device Product Level

24VAC Average Power Consumption

24VAC Peak Power Consumption

Compatible Devices List

Application Code memory Size

Microcontroller Part Number

MAC Address

Yes/No

The Service Center is accessed from the Home Screen under the Menu Button > Advanced Settings > View Support Service Control Center.
Connects to the strongest channel and broadcasts a Thermostat ID for connecting to the Lennox® Smart Tech Thermostat App. See page 2. Stops broadcasting.
Notes:
Equipment specifications.

L40 Smart Wi-Fi Thermostat / Page 13

DEALER SERVICE CENTER - INSTALLER SETTINGS (THERMOSTAT)

NOTE - INSTALLER SETTINGS SHOWN ARE ON THE THERMOSTAT ONLY! ADDITIONAL SETTINGS ARE AVAILABLE ON THE LENNOX® SMART TECH APP. SEE page 2.

EQUIPMENT SETTINGS (Continued)

THERMOSTAT SETTING (default is BOLD)

Notes:

Settings

Temp Reading Calibration

­5 to 5°F (0°F)

Auto-Changeover - Temp Deadband

3 to 9°F (3°F)

Max Heat Setpoint

60 to 90°F (90°F)

Min Cool Setpoint

60 to 90°F (60°F)

Min Gas Heating Off Time

1.5 to 10 min. (1.5 min.)

1st Stage Differential

0.5 to 3°F (1.0°F)

2nd Stage Differential

0.5 to 8°F (1.0°F)

Smooth Setback Recovery

Enabled/Disabled

- - -

Balance Point Control

Enabled/Disabled

Staged Delay Timers

Enabled/Disabled

Outdoor Temperature

­10 to 10°F (0°F)

Aux Heating Activation

0 to 10°F (2.5°F)

Screen Saver

Off/Power Save/Dim

Wide Setpoint

Off

Reset Button

Resets the thermostat

NON-COMMUNICATING EQUIPMENT

Indoor

1 Stage

About

Electric Heat

Model Number Serial Number

1 Stage

About

Model Number

Electric No Heat

- - Serial Number

1 Stage Gas

About

Model Number Serial Number

Outdoor

1 Stage AC Unit

About

Model Number Serial Number

Outdoor Unit Capacity

18 to 60 kBtu (36 kBtu)

O/B Terminal

O (Cooling) or B (Heating)

Compressor Short Cycle Delay 60 to 300 sec (300 sec)

1 Stage

About

Model Number

- - -

Heat Pump

Serial Number

Balance Point Control

Disabled or Enabled

Outdoor Unit Capacity

18 to 60 kBtu (36 kBtu)

O/B Terminal

O (Cooling) or B (Heating)

Compressor Short Cycle Delay 60 to 300 sec (300 sec)

Add/Remove Equipment

Indoor Outdoor

Change existing equipment. See Indoor/ Outdoor selections above.

Reset

Restart Thermostat

Restarts Thermostat.

Reconfigure System

Resets existing outdoor/indoor units and settings.

Factory Reset

Reset to factory default settings.

L40 Smart Wi-Fi Thermostat / Page 14

DEALER SERVICE CENTER - INSTALLER SETTINGS (THERMOSTAT)
NOTE - INSTALLER SETTINGS SHOWN ARE ON THE THERMOSTAT ONLY! ADDITIONAL SETTINGS ARE AVAILABLE ON THE LENNOX® SMART TECH APP. SEE page 2.
NOTIFICATIONS
Provides information for active and previous (cleared) notifications. When selecting either a cleared or active notification a brief description and alert code will be displayed. Notifications are color-coded to display - Urgent (red), Service Soon (orange) and maintenance (yellow) To expand a notification for more details of the alert code, touch the arrow to expand the description. Touch the Cleared button to move the notification to the cleared area.

INSTALLATION REPORT

Displays Installer and Customer information along with various parameters and settings for the system, outdoor equipment and indoor equipment at the time of installation.

Update Report Button

INFORMATION

Information Screen

Displays Dealer Information and General Settings from the Initial Setup Screen.

EXIT DEALER SERVICE CENTER

Yes/No

Installation report is based on various settings that were configured in the Equipment screens previously. Only certain parameters are displayed depending on the type of system installed (air conditioner, heat pump, dualfuel). Touch the different selections to view the individual information screens.
Installer can generate a PDF file of the report to email to a homeowner. Reports are available at www.LennoxPros.com.
See page 12.
Returns to the Home Screen.

L40 Smart Wi-Fi Thermostat / Page 15

SPECIFICATIONS NOTE - For use with residential equipment only.
Order No. - 27V51 Temperature Setting Range · Heating - 60 to 87°F · Cooling - 63 to 90°F · Wider setting (configured on the Lennox® Home App):
· Heating - 40 to 99°F · Cooling - 60 to 99°F
Power Supply · 24VAC (18 to 30VAC maximum), 50/60Hz
Clock Accuracy · ± 10 minutes per year
Terminals Spring-loaded or screw type terminals for easy connections. ¹ Heat / 1 cool single-stage · R - 24VAC power · Y - 1st Stage Heating or Cooling · W - 1st Stage Heating (AC or Emergency Heat) or 2nd
Stage Heating (Heat Pump) · G - Fan · O/B - Reversing Valve (Cooling/Heating) · C - Common 24VAC
1 Configured in advance settings > terminal settings.

Dimensions · Thermostat (H x W x D) - 2-13/16 x 2-13/16 x 1/4 in. (71
x 71 x 6 mm)
· Wallplate (H x W x D) - 4-7/16 x 4-7/16 x 1/4 in. (113 x 113 x 6 mm)
Backup · Non-volatile memory maintains all programming in the
event of a power outage

Visit us at www.Lennox.com For the latest technical information, www.LennoxPros.com Contact us at 1-800-4-LENNOX

NOTE - Due to Lennox' ongoing commitment to quality, Specifications, Ratings and Dimensions subject to change without notice and without incurring liability.

Improper installation, adjustment, alteration, service or maintenance can cause property damage or personal injury.

Installation and service must be performed by a qualified installer and servicing agency.

©2025 Lennox Industries, Inc.


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