Lennox S40 Smart Thermostat
The ultimate controller for more precise comfort
We have higher standards. Others think so, too.
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.
Balanced Temperature and Humidity
The Feels Like™ feature creates the temperature you want to feel, not just the temperature you set—much like the "Feels Like" temperature in a weather report. So when you set it to 72 F, it feels like 72.
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.
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.
Digitally intelligent for precision and efficiency
This truly digital product is part of a fully communicating home comfort system. Sensors in the equipment allow the thermostat to diagnose issues and automatically make system adjustments to more precisely and efficiently maintain temperature, humidity and air quality.
Complete control at home or away
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.
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.
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.
Take your home comfort system to the next level
Complement your system with our suite of technologically advanced accessories to more precisely and efficiently maintain the temperature and air quality in your home. The Lennox Smart Air Quality Monitor is the only monitor of its kind that can detect air pollutants and trigger air cleaning on demand. Add on Lennox Smart Room Sensors to more evenly balance temperatures across rooms, plus the Lennox Wireless Extender to nearly double the connection coverage area and ensure you get the most from your communicating equipment. Altogether, it’s the most advanced accessories package available that delivers next-level perfect air.
Ratings & Reviews
See what other customers are saying about
Lennox S40 Smart Thermostat
The S40 works really well for meJanuary 23, 2024
I've had several Honeywell Wi-Fi thermostats over the years, and they all worked well, this S40 is better than Honeywell for my HVAC system. My new Lennox system was installed mid-October 2023, so I've had it for a little over three months now. My Lennox dealer recommended a specific gas furnace, the whole-house humidifier, upgrading my 1" filter to a 5" filter, plus this S40. It's all working as advertised. As other's have stated, waking the S40 up by approaching it (proximity) doesn't seem to work so well. It sure doesn't work for us, but this is not an important feature to me either, as I just gently touch the screen on the S40 to wake it up. My first S40 was replaced under warranty within a few days, because the auto-brightness did not work, the auto-brightness does work on the replacement S40. At least one other reviewer said only one person in the house can have the smart-phone app installed and working, but this is not my experience. My wife and I both have the S40 app installed on our smart-phones, and we can both access our S40 from our respective phones, no issues at all. Making changes to the S40 is as easy as it should be, via the smart-phone app or at the S40 itself. I've had no issues at all changing settings. Some other reviewers indicated that there is some sort of delay when they make configuration changes to their S40, this is not the case for me, my S40 works just like you'd expect it to work. For me the S40 is just one piece to the puzzle, but it's an important piece for sure, but just one piece. The built-in integration between the S40 and the whole-house humidifier was an added bonus. The S40 knows the actual humidity in the house, you set the humidity level you'd like your house to be in the S40, then the S40 turns on the whole-house humidifier as needed automatically. There are some other features that I like with the S40 but I've written enough here already. Long-story short, it's a really good thermostat, but it's an excellent thermostat when you pair the S40 with the other Lennox components.
Yes, I recommend this product.
Age: 55 - 65
Reason for Replacement: Planned
Could be great, but poorly tested and designedDecember 19, 2023
The signature series heat pump is fantastic, but this thermostat has the features of a $50 generic Honeywell and the cost of an iPhone. The sensor to wake the display doesn’t work and the touchscreen is very laggy (5 seconds) about every other day. The UX is just also not well designed with a lot of wasted space and not as functional or intuitive as it could be. I don’t use it, but the weather “screensaver” is just bug text in the middle of the interior temperature (which is not weather by the way) and little text of outdoor conditions in the corner that’s less helpful than on the main screen. It’s not clear if the main temperature displayed is from the thermostat, or averaged with the room sensors if applicable, even the My Home Screen doesn’t clearly show the temps from each sensor explicitly plus the averaged temp actually used for controls. The room sensor ability to impact the controls in general is pretty limited (I’m comparing to an ecobee, which is much cheaper and has more features).
Age: 35 to 44
Please add Apple HomeKit support!December 03, 2023
I got a new system and it replaced my Nest thermostat. The biggest downside to this thermostat is it doesn’t support Apple HomeKit. The S30 and other Lennox thermostats do, so please add this soon!
Age: 35 to 44
Reason for Replacement: Emergency