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The Ultimate Side of Perfect Air

Not only is the Lennox S40 Smart Thermostat part of the Dave Lennox Signature® Collection, it’s part of the Ultimate Comfort System™. This combines the best of everything Lennox has to offer to create an unprecedented whole-home comfort system that seamlessly and intelligently works together to stay finely tuned to your home and deliver consistently clean, perfect air.

Why do we recommend Lennox furnaces? Like us, they have spent years providing the very best they can to their customers. Quality products, industry-leading technology and warranty, installed by professionals at Air Design Services. A winning combination for any homeowner.

Contact us today for a free no-obligation furnace quote in London and Strathroy!

Lennox S40 Thermostat

Lennox S40 Smart Thermostat

The ultimate controller for more precise comfort

Advanced diagnostics keep your system at peak performance

Protect your investment and peace of mind with active monitoring of system operations through your Lennox S40 Smart Thermostat. This feature is free of charge and provides basic maintenance reminders, alerts you of potential issues, and can even allow you to remotely share diagnostics with your local Lennox dealer to troubleshoot and fix problems. This proactive care helps eliminate downtime and avoid unnecessary service visits and repair costs, ensuring nothing short of perfect air.

Efficiency at your fingertips

One-touch Away Mode overrides your regular programming schedule with a single touch and sets back your heating and cooling set points to save energy.

Complete control at home or away

Remote control of your home environment is just one touch or voice command away with the Lennox S40 Smart Thermostat. Monitor temperatures and schedules from anywhere in the world using the Lennox Smart Thermostat app on your smartphone or tablet. Available on the App Store and Google Play.

The Lennox S40 Smart Thermostat effortlessly integrates with a range of smart home devices—from premium smart home systems like Control4 to popular virtual assistants like Amazon Alexa and Google Assistant.

We have higher standards.

Year after year, leading institutions choose to award Lennox for its innovative initiatives in product design which helps homeowners define what perfect air means to them. Below you’ll find a recognition this product has received.

Product Specifications


System Compatibility Works with premium Lennox® communicating equipment only AND pairs with Lennox Smart Accessories (Smart Room Sensors, Smart Air Quality Monitor and Wireless Extender)

Amazon Alexa

Allows you to voice control your HVAC system through Amazon Alexa-enabled devices


Google Assistant

Allows you to voice control your HVAC system through Google Assistant-compatible devices



Versatile programming options offer custom comfort and energy savings


Smooth Setback Recovery

Senses extreme temperature changes and begins the temperature recovery process up to 2 hours before the programmed time


Smart Away

Uses the GPS in your smartphone to detect when you're leaving, and automatically changes the temperature to a more energy-efficient setting


Schedule IQ

Allows you to only program your thermostat once. Whenever there's a change in your routine, the thermostat adapts heating and cooling to match


One-Touch Away Mode

Overrides your regular programming schedule when you're away and automatically turns down heating or cooling to save energy


Allergen Defender

Monitors the air quality and pollen levels of your local zip code and automatically turns the fan on to clean your home\u2019s air when outdoor levels are high


Feels Like

Similar to the \"Feels Like\" temperature in a weather report, this feature takes into account temperature and humidity to create a comfortable environment


Filter Reminder

Reminds you when its time to change the filter


Auto Changeover

Decides between heating and cooling operation, depending on indoor temperature



Features a large, easy-to-use display with adjustable brightness


Photo Display

Allows you to display a personal photo as the screensaver of your thermostat


Weather Screen Savers

Themed screen savers on the 7\" HD color touchscreen are designed with graphics that tell you what weather conditions are like outside


Dual-Fuel Capability

Increases the efficiency of dual-fuel heating systems by automatically alternating between gas and electric operation


Energy Reports

Show how often and how long the heating or cooling system has run for the month


Humidity Control

Works with the whole-house humidity-control systems to adjust the home's humidity level


Remote Capability

Monitor and adjust temperatures and schedules from anywhere in the world using the iComfort App and your smartphone, tablet or other web-enabled device


Emailed Alerts

Provides detailed diagnostics and reminds your Dealer when service is needed


Remote Monitoring

Allows Lennox dealers to analyze your system from anywhere via their computer or mobile device


Remote Troubleshooting

Makes it possible for dealers to use their mobile device to adjust system parameters to fix problems, without ever making a trip to your home



10-Year Limited Warranty