Lennox L40 Smart Thermostat
The upgraded version of ComfortSense 5500 — simplified comfort, advanced features.
ENERGY STAR® Qualified
5-Year Limited Warranty
Features
Schedule IQ Technology
Uses homeowner inputs and Smart Away® geo-fencing capabilities to learn your routine and create a schedule that maintains comfort when the home is occupied and help save energy when it's not.
Complete control at home or away
Remote control of your home environment is just one touch or voice command away with the Lennox L40 Smart Thermostat. Monitor temperatures and schedules from anywhere in the world using the Lennox Home app on your smartphone or tablet. Available on the App Store and Google Play.
ENERGY STAR® Certified
Heating, ventilation and air-conditioning (HVAC) equipment with the ENERGY STAR label meets or exceeds federal guidelines for energy-efficient performance.
Access your Lennox L40 Smart Thermostat from your choice of smart home device
The Lennox L40 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, Google Assistant and Building36.
Custom equipment profiles for perfect installs
Thanks to its custom equipment profiles configured by your local Lennox dealer, the Lennox L40 Smart Thermostat can help seamlessly install, service and fine tune your home’s system based on your location and climate. This advanced technology along with its speedy, secure wireless connection allows you to easily and quickly get up and running with the perfect air you’re looking for.
Modern design, simple navigation
The Lennox L40 Smart Thermostat's four-color, touchscreen display is easy to use, with large, legible fonts and organized screens that make setting your thermostat a breeze. With a slim profile and glass-like finish, it is more attractive on your wall than traditional thermostats.
Ratings & Reviews
See what other customers are saying about
Lennox L40 Smart Thermostat
4/5
Updated Review: Big Improvement After Software Upd
June 25, 2026I’m updating my original review because Lennox appears to have pushed a software update that significantly improves the L40 thermostat experience. Previously, I was very disappointed because many basic features could only be controlled through the Lennox mobile app, making the thermostat feel more like an app accessory than a complete thermostat. After the update, most of the functionality can now be controlled directly from the thermostat itself, which is a major improvement. Because of this, I’m updating my rating to 4 out of 5 stars. The one major feature still missing from the thermostat itself is the ability to edit schedules. If schedule editing were available directly on the thermostat, I would give it a solid 5 out of 5. At this point, that appears to be the only major functional limitation remaining. There is also one issue that seems to have appeared after the update: the screen saver dim mode no longer works correctly. When the screen is on, the brightness appears to stay at the normal or maximum level instead of dimming properly. That is another reason I’m keeping the rating at 4 stars for now. Overall, though, this update is a big step in the right direction. Great job, Lennox, for listening to customer feedback! I hope to see these final improvements addressed in a future update.
Yes, I recommend this product.
4/5
5/5
Review of WIFI-THERMOSTAT-L40
October 15, 2025The thermostat was easy to install and set-up was very intuitive. Everything worked as it should and the set-up did not time-out as you proceeded through the various steps.
Yes, I recommend this product.
Staten Island, NY
Gender: Male
5/5
3/5
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