Review: Lennox icomfort WiFi Thermostat–Sonos For Air Conditioners

“It’s Sonos for air conditioners.” That’s the first thing my wife said when she saw the new Lennox XC21 air conditioner installed in our home in Miami, Florida, after replacing a 10-year old Carrier unit. Not since I installed Sonos in our home in 2006 has a new technology received a 10 out of 10 wife acceptance factor.

Yes, my wife knows the air conditioner is listed as an Energy Star most efficient 2012. And, that it will save us money.  Never before has our 1926 (leaky) house reached 43%-48% indoor humidity, making it more comfortable than ever. Yet, it’s the thermostat. The 7″ color display. The remote access. The one-touch away mode.

icomfort WiFi Thermostat-Home Screen
The Lennox icomfort home screen connected to WiFi, which enables remote access and weather forecasts provided by

We use the thermostat everyday, whether at home or on-the-go, using the Lennox icomfort iPhone app (free). The Lennox XC21 air conditioner system was installed on June 18, 2012 by Engineered Air in Pompano Beach, FL. Through Ken Kiefer at Engineered Air, I was able to purchase an icomfort WiFi thermostat a couple of weeks before it became generally available. I’m glad I did. Thanks, Ken!

Intelligent Thermostats: The Apple Impact

Clearly, thermostats are becoming more intelligent, primarily by connecting them to the web and enabling direct communications with air handlers and outdoor condenser units. Web-enabling thermostats provides an easy way to monitor and adjust temperature settings, set/cancel away settings, program daily temperature programs and view past usage. And, creating apps for mobile devices (iPhone, Android, iPad) allows anywhere access. Direct communications between the thermostat and the air handler and condenser units simplifies diagnostics for technicians, whether I provide error codes to a technician when calling in for service or the error codes are transmitted proactively to my dealer.

Set-up and Configuration

icomfort WiFi Thermostat-WiFi Settings
WiFi settings screen connected to my home network and registered with the Lennox web site. I love the auto firmware upgrade. Not all thermostats auto-update.

Set-up and configuration was a snap. I enabled WiFi on the thermostat, which allowed the thermostat to see my wireless network. I entered the WiFi password on the thermostat and was connected to my wireless router (Apple Airport Extreme 4th Generation). No futzing with firewall settings. It just worked. Like Apple products do.

Then, the thermostat directed me to create an account on Account set-up was simple consisting of 3 steps: My Profile, My System, and My Dealer.

icomfort WiFi Thermostat-Web Setup
The “My System” step during set-up on I’m not sure why they asked for home details, but I entered them anyway.

Set-up was smooth, except my preferred dealer (Engineered Air, LLC) did not appear based on my zip code, even when selecting a 100 mile radius (my dealer is 33 miles away). I typed in my dealer’s zip code (33064) and then their name appeared on the list. Bam. I had my dealer associated with my account.

Things I like:

  • The 7″ screen is gorgeous
  • One-touch for “away” or “cancel away” settings
  • Firmware auto-update (I looked at a Trane system and the Trane Comfort Link II thermostat, which requires downloading firmware updates to a computer and transferring them via SD card to the Trane thermostat)
  • Free remote access (At time of this blog post, the Trane Comfort Link II required a Nexia Home Intelligence account – $8.99 monthly/$99 yearly)

Suggested Improvements:

  • Show outdoor humidity
  • Clicking on the weather icon should show the day’s hourly weather forecast
  • Usage monitoring bar chart (day/week/month). I would also like to plug in my electricity rate to see how much my air conditioner costs to run

iComfort iPhone App

For the first 2 weeks, I couldn’t stop opening the Lennox iComfort iPhone app (1.0.2). I would constantly check the house temperature throughout the day. It was a feeling of power to know that I could control the temperature anywhere I had a cellphone connection. This is great when traveling in case you can’t remember if you turned down the air conditioner before leaving or not.

The iComfort iPhone App is elegantly simple and consists of 3 screens.

icomfort WiFi Thermostat-iPhone App
The 3 main screens of the iComfort iPhone app. I generally leave the app on the temperature (middle) screen, leaving the app running in the background.

Things I Like:

  • It’s simple
  • One-touch for “away” or “cancel away” settings. This is the feature that I use the most.
  • Multiple homes and thermostats can be managed from the iPhone app

Suggested Improvements:

  • Timestamp of last temperature update – I find myself going to the “My Homes” screen and selecting my home to force an update of the temperature screen. Otherwise, you cannot tell if the on-screen temperature is cached or is current.
  • Show outdoor temperature & humidity
  • Geo-Fencing – Once I pass a geo-fence of .5 miles away from my home (user-configurable), I would like the thermostat to automatically set itself for “away”. When I pass within .5 miles of my home, the “away” setting is automatically cancelled.

iComfort iPad App

The iComfort iPad app (1.0.7) was first released in late July 2012. The app largely seems to be a copy of the wall-mounted thermostat, albeit with less functionality. The weather icon is not clickable as it is on the wall-mounted thermostat. Overall, the iPad app feels like a minimum viable product. But it works. It has the basic functionality of the wall-mounted thermostat, but I can see a lot of potential, especially for energy usage monitoring.

icomfort WiFi Thermostat-Home Screen-Cooling
Lennox iComfort iPad app main screen. The weather icon is not clickable, but there are lots of other weather apps for the iPad.

iComfort Web App

The iComfort web app is straight-forward, offering the same ability to change temperature settings, set/cancel “away” mode, and see the weather forecast. It is the easiest way to get system information. For those cases when I don’t have my mobile with me, it’s nice to be able to login to the web app, but I find that I rarely access it. The mobile apps are far more convenient. While fully functional, the web app doesn’t have the same quality of graphical design compared to the thermostat or mobile apps. The fonts are garish and everything has sharp corners.

icomfort WiFi Thermostat-Web Thermostat
Lennox iComfort web app home screen. Definitely less design polish than the thermostat or the iphone/ipad app. Viewed in Google Chrome.


After having used the Lennox iComfort WiFi thermostat for about 45 days, I will never go back to a programmable or conventional thermostat. Not only does my wife love it, I do too. In fact, the functionality of the thermostat has now made it into my top purchase criteria for new air conditioner systems:

  1. System rated as Energy Star most-efficient central air conditioner
  2. Intelligent thermostat functionality
    1. Is remote access free?
    2. Ease of firmware updates
    3. Usage monitoring
  3. Quality of dealer install

Give the Lennox iComfort WiFi thermostat a try, either through a local dealer or buy online (about $350)

45 Responses to “Review: Lennox icomfort WiFi Thermostat–Sonos For Air Conditioners”

  1. John

    Great article! Nicely written. Installed the XC-21 in December before the iComfort was available.
    Plan on upgrading soon. It would be wonderful if you could monitor your electrical usage.
    My only concern living in a 10yo condo in Bonita Springs, FL, is that the system is making the house too dry! Indoor humidity runs around 42%.

    The dealer is coming out this week to see if the system can be adjusted.

    Not sure about your Geo Fencing suggestion in a situation where someone else may be at home. Otherwise, appreciate the detail. Thanks.

    • Bryon Thomas

      I will watch energy usage closely over the next 12 months. The new XC-21 AC was installed on June 18, 2012. In the first month with the new AC, 27 kWh more were used. But this is not a fair comparison for 2 reasons. In the month prior, the old AC was turned off for 4-6 hours at a time because it did not cool. Then, when turned on again, it would cool moderately for a couple hours. This usage pattern obviously conserves energy (but it was hot!). The second reason is that there was a heat wave in July, setting record-high temperatures, including in South Florida. So energy usage may have been greater than normal.

      Here are my FPL bills for the month before the new AC was installed and the month after.

      First month with new AC
      6/20/12 to 7/20/12 – $140.33 (1286 kWh)

      Month before installation of new AC
      5/21/12 to 6/20/12 – $140.33 (1259 kWh)

      (How ironic that both bills cost exactly the same!)

  2. Melissa Furman

    This sounds like a fantastic system! It rivals our Nest system, with which I am not happy. Hmmm. Looks like it’s worth returning the Nest and swapping for the Lennox iComfort! Great overview and suggestions.

  3. JM

    Thanks for your review. I two purchased 2 XC21 with two iComforts in February.I am seriously considering this however why is not comparable with zigbee or zwave ?

  4. LP

    I have had nothing but problems with my Lennox iComfort thermostat. The thermostat keeps losing contact with the server. I have replaced the thermostat twice and both units lasted two weeks before losing access to the server. My dealer is totally baffled and Lennox says the problem is not on their end.

    • bryonthomas

      I suspect the issue is with your wireless network router configuration. Who is your ISP? Once I configured my home network to isolate my IPTV traffic from my data network as per this post (, my wireless connection to my icomfort thermostat has been **rock solid**. I use Apple Airport Extreme routers (4th generation and 5th generation) and Netgear GS108 switches. Prior to this new configuration, the wireless connection to my icomfort thermostat would drop intermittently, at least once per week. It is possible that your icomfort thermostat is being overwhelmed by multicast network traffic, which causes the network connection to drop.

      • respond

        Can you please elaborate on what you did to fix your issue? I have Comcast and I just upgraded my router from a Linksys WRT310N to the new Cisco EA6500 and I started having all sorts of problems with the iComfort. Connection keeps dropping and often the connection is up but the iComfort shows it as down and I can still access it remotely.

  5. Angrylennoxcustomer

    I regret purchasing my iComfort thermostat. Lennox just doesn’t know how to produce technology beyond a good HVAC system and I should have bought a secondary controller such as a nest. I’ve had my iComfort controller for six months and it just went completely black this morning on one of the coldest days of the year. I’ll be ripping this POS out this morning and installing something else if they can’t Frankenstein it again.

  6. Guest

    To “bryonthomas ” – can you please elaborate on what you did to fix your issue? I just upgraded my router from a Linksys WRT310N to the new Cisco EA6500 and I started having all sorts of problems with the iComfort. Connection keeps dropping and often the connection is up but the iComfort shows it as down.

    • bryonthomas

      I configured my home network as per my comment below –

      Recently, I have noticed that my iComfort thermostat loses its wifi connection periodically, as evidenced by the warning symbol in the lower left of the thermostat screen. I haven’t tested to see if I still can see the thermostat via the iPhone app or the web app even when this alert appears. In other words, does the wifi connection remain even though there is the alert in the lower left of the screen? This is something I need to test.

      In general, I’m not sure what is causing all of this. To resolve, I manually disconnect from my Airport Extreme access point and then reconnect. I will watch this wifi connection issue closely and update this thread with my findings.

  7. Denny

    I’ll tell you what. When first installed the thermostat worked randomly. I could switch of the HVAC system and wait 10 seconds and turn in back on to re-establish connection with the WiFi thermostat. No it will not connect for anything. I have two personal computers and a television which have no problem whatsoever. But the thermostat tells me my WiFi is not functioning. Well, I set my router directly on top of the thermostat and it still says the problem is my wireless internet connection and that I should contact my Internet Service Provider. What a flipping joke. The dealer has their hands tied. Lennox will not admit they have a serious problem here. These devices are not cheap and THEY DO NOT WORK. The worse part is Lennox just sticking their head in the sand and screaming at you to quit complaining and contact you ISP. I will not recommend this unit to anyone. Save your money !!!! Oh, the concept is nice and if LENOX would step up and do the right thing and fix these buggers they would certainly have a winner. But, THEY REFUSE TO RECAGNISE THE PROBLEM. AND ARE TOO BUSY POINT THE FINGER AT THE CUSTOMER. DON’T BUY THIS PIECE OF CRAP !!!

    • bryonthomas

      Denny, I too have become frustrated with dropped wifi connections between my wireless access point and iComfort thermostat. Have you tested that accessing your thermostat from directly from the web app or the iOS app? Can you still see your thermostat one of these ways even though the thermostat shows a missing wifi connection? This is something I’m going to test the next time my thermostat drops its wifi connection.

  8. Chuck

    The iComfort thermostat is feature-laden, expensive and unfortunately, as far as the WiFi part of the product is concerned, not very reliable. We all understand that anything based on the Internet probably isn’t going to be a “guaranteed delivery” situation but if it’s advertised to function on the average WiFi system it should do that. Ours was installed in March, 2013 and it hasn’t had a WiFi signal for about 60% of the time. The access point is less than 30 feet of the thermostat and every other WiFi device in the house reports a good signal so I am disinclined to blame my infrastructure. When it does have a connection the server side isn’t always working. Lennox sent us an email about a month ago telling us that all the server side issues were resolved and that we should see great service; however that hasn’t materialized and in fact, if anything it’s worse, exacerbated by the unit’s inability to hold a connection. I realize that this is clearly a “your mileage may vary” situation but my advice to anyone thinking about buying an iComfort thermostat is to investigate very thoroughly before investing in one of these and don’t install without a money-back guarantee. The concept is brilliant but the execution isn’t worth the money and frustration.

    • Bryon Thomas

      Over the past 12 months that I have owned the icomfort thermostat, a reliable WiFi connection between the thermostat and my access point has been the number one issue. Yes, it’s incredibly frustrating.

  9. Johnw41

    Same problem as many others. Had the thermostat since June 2013. Wifi connection drops seemingly at random. Reset the router, and I’m good for another random period (usually only a few hours). Three computers, various iPads/Pods stay connected all the time. The router still thinks the thermostat is connected. Perhaps this thing needs an upgrade to Wireless N – I had to hunt around to find a router that still supports Wireless B (d-link DIR515). Based on other experience, I won’t bother to call Lennox. Enough frustration with help lines……

  10. Garrett

    Ok. Well I for one love the system but hate the wifi connection issues. In may be prime example that lennox has issues to work out. Besides installing 7 lennox units lwith upgrade pure air and icomfort thermostats I also installed a professional grade ruckus wireless enterprise professional network with 8 access points. This leaves none of the thermoatats more than 10 feet from the wifi signal which was tested and confirmed to be functioning. Also my Internet connection is a 100 meg up and down business service. Which is stable and consistent. Yet each of my thermoatats take turn a losing network connection while simultaneously still showing connected when you check the configuration. Lennox blames the network but it is clearly not the network. This is frustrating and it is obvious that they have a problem that hey refuse to address.

  11. Ted

    I’m glad its not just me suffering icomfort wifi fatigue. I have two Lennox icomfort controls, recently installed, and they are constantly losing their connections. A message to Lennox – This Is Not A Router Issue! I have a professional wireless network system and I’ve measured strong signal strength to where both of the thermostats are located, including those times where signal is lost at those termostates. I’ve tested the configuration against a myriad of wireless devices, none of which suffer the drop offs that the icomfort units are experiencing.

  12. garry

    I have a strong signal. My dumb thermostat thinks that it is a weak signal and refuses to connect. It is a defective product. I’m TOTALLY FED UP with this thing, and I now want to change it to a non-wifi thermostat, because this one is useless.

    • bryonthomas

      I remember being very frustrated with my icomfort thermostat in mid 2012 because of a constantly dropped wireless signal. Since the May 22, 2013 “connection outage resolved” notice from Lennox, I have had a rock-solid WiFi connection to my Airport Extreme access point. I wrote a bit more about that in this post What access point are you using?

      On a second AC unit in another building, I installed the Nest thermostat version 2. That thing can’t hold a stable WiFi connection at all to the Airport Extreme network. It’s disconnected easily 50% of the time. The Nest WiFi connection stability is even worse than the icomfort at its worst moment. I made the recommended changes as per Nest tech support and it still does not hold a stable WiFi connection. More digging to do.

      In general, a stable WiFi connection plagues the icomfort and Nest thermostats. I suspect other smart thermostats have a similar problem. Is it the thermostat or the WiFi network? Vendors say its the WiFi network. Customers say its the thermostat. Regardless, the smart thermostat vendors need to determine a way to make these thermostats “just work” with every WiFi network. If that means providing a utility for Mac/Windows for testing, then so be it. Or why not add an ethernet port to the thermostats for when there is cabling access?

      • Dave

        Same issue as many others. Very unreliable server. Constantly loosing connection and getting Lennox notice that server is temporaily down. I had expected much better after purchasing two top of the line Lennox units.

      • Diana

        arghhh where can we leave feedback to Lennox they need to work with their connectivity. As many customers my WIFI connection with any device at the same spot as my thermostat is brilliant! Yet I get the message that I am not connected to the servers… This is extremely frustrating.

        • Bryon Thomas

          Yes, it is frustrating! I suggest sending an email to or posting a tweet for @LennoxAir. They will likely respond to your tweet and tell you to send an email to the address above. That is what they did when I left a tweetstorm when my Lennox AC failed a couple months ago. See

        • Freddy

          I have an icomfort for almost 2 years
          And I have been having trouble with the exterior temperature probe .as soon as the temperature gets cold the temperature shown on the thermostate can vary by 5-7 degrees celcius
          Does anyo e have this problem ?

          • Bryon Thomas

            Miami, Florida is a mild climate. Sounds like it is much warmer than where you are located. Regardless, I do not trust the temperature reading on my external thermostat. I have noticed it can vary by 3-4 degrees fahrenheit. If the sun hits the outdoor condenser unit, the temperature reading can vary by 20-30 degrees fahrenheit. For that reason, I configure the iComfort thermostat to use temperature readings from the Internet and not the outdoor temperature sensor. With that said, you may have a defective outdoor temperature sensor. During your next AC service, I suggest having the tech take a look at the sensor.

  13. garry

    It just DOESN’T WORK. Wi-fi is a big problem for the wi-fi thermostat, surprisingly.

  14. User

    Does anyone have solid answers for the below?

    1) I find the motion effect of the snow flakes blowing around showing cooling mode to be annoying and distracting. Can the motion affect be turned off or simplified ?

    2) I have to install several thermostats in bedrooms. Can this unit be programmed to go dark, so it does not become an unwanted nightlight ?

    3) Can you adjust the hysteresis, (aka set-point differential)? I like to control the temperature tightly + or – 1°

    • bryonthomas

      1) I have not been able to find a way to change the animation of the animated snowflakes. Personally, I don’t find them annoying, but that is personal preference

      2) Go to Display Settings and ensure screen saver is “On”. Screen goes blank after about 60 seconds.

      3) I couldn’t find a way to control the hysteresis setting. In general usage, if there is a + or – 1 degree temperature reading on the thermostat from the temperature set point, the HVAC system will turn on.

  15. Kristin

    Does anyone know why my screen just goes black? Are there batteries to replace inside the icomfort thermostat? It’s a holiday and no air conditioning.

    • Bryon Thomas

      Have you checked that the condensate drain is not clogged? If the drain is clogged, the float switch in the overflow pan will cause the system to cut power to the AC system and your screen will go black. Vacuum out the AC drain line from outside your house. If this doesn’t resolve your problem, then it may be a faulty icomfort thermostat. My AC tech told me he has replaced a number of icomfort thermostats due to black screens if the first steps don’t resolve the problem. Good luck.

      • Stacy Robinson

        We had the same issue. Thermostat went black and a/c stopped working. Realized overflow had been tripped. Flushed line from outside with garden hose which removed slime and system turned back on. Didn’t realize thermostat would turn off when system shut off. Would be nice if they included this info in manual.

  16. William Fuchs

    My WiFi connection drops out every time I turn off my smart phone. It prompts me that I have no WiFi connection. The only remedy for me is to log back on or worse uninstall and reinstall. I am a brand new owner, so any help will deeply be appreciated….thank you. Bill

  17. Darlene

    I am a new owner of the icomfort thermostat and was wondering if I can still manually adjust temperature of my heating system if I have lost wifi connection?

    • Bryon Thomas

      Yes, you can still adjust the thermostat temperature from the wall-mounted thermostat without a WiFi connection. However, you cannot adjust the temperature from your smartphone without a WiFi connection.

  18. Keith Campbell

    The only problem I have with the iComfort is that it does not function properly when you use the Celsius setting for the temperature. In Fahrenheit, you can go up in 1 degree increments. In Celsius, you can go up in 0.5 degree increments – EXCEPT that you CANNOT set the temperature to 24.5 degrees. This means that you go from 24 degrees to 25 degrees only – in F, this is equivalent to moving from 75.2 to 77 – almost a full 2 degrees difference.

    I called Lennox customer support to ask about the problem. They confirmed that the system was programmed so that you cannot set the temperature to 24.5 Celsius, but you can set it to 76 Fahrenheit.

    Really bizarre bug in their system, if you ask me.

  19. Russ

    My 2-year-old icomfort WiFi just went blank on me. In the past, when it froze, I learned that pulling it off the wall and placing it back on can solve the problem, but that didn’t work for this problem.

    I work on air traffic control automation systems, but I am not the slightest bit interested in programming my thermostat or controlling it from anywhere other than the wall. I see that these things go for around $200 and up. Is there a cheap plugin replacement for this piece of high-tech junk that crapped out in two years? Thanks.

    • Bryon Thomas

      That has happened to me as well. Check that condensate drain is clean. Go outside and vacuum the drain with a shop vac. The float switch in the overflow pan is doing its job and has cut power to the AC unit to prevent water overflow. Sometimes, water will drain slowly, allowing the AC unit to come back on, making one think there is a problem with the iComfort thermostat. The problem is with a clogged condensate drain.

      • Russ

        Thanks for the tip, but the problem turned out the be a loss of electric power to the unit. I guess I owe icomfort an apology for the “junk” remark. Then again, I would have been happy with a cheaper basic unit to start with.

  20. Tim

    I love my Icomfort. I have had no trouble in 2 yr. use. I wonder can the humidity adjustment be automaticly adjusted using accucast temp. Or do I have to keep adjusting it manually.

    • Bryon Thomas

      Good question. I was not able to figure out a way to do that on my iComfort. I suggest contacting Lennox directly.

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  22. Rich

    Your comment about Sonos really caught my attention. Have you had any issues with Sonos after installing the icomfort? I have had intermittent issue with Sonos. Very frustrating.

    • Bryon Thomas

      Of all the home electronic/home automation products that I have used over the years, Sonos is the one product that has been trouble-free. Once they moved beyond their “mesh technology” and started to use standard WiFi, it has worked flawlessly. If I were to guess, home networking issues are causing your problems. How do I know? I’ve been there. Pulled my hair out for years due to intermittent network problems: WiFi laptop slowness, network quality degradation, etc. I called my Internet provider (AT&T U-verse) to solve the problem. They couldn’t. They only get you a signal up to their NAD (Network Access Device). In the end, I contacted a local CEDIA (home automation pros) to have them correctly configure my U-verse box, 2 Apple Airport Routers, IP addresses, and home network. About $300 and 4 hours later, my network was correctly configured. Mind you, I have over 50 devices on my network. Since then, everything has worked flawlessly. Knock on wood. Good luck. And you **will** love Sonos.

  23. Kate Queen

    Our Lennox icomfort stopped working properly. We can see the screen, but the touch screen isn’t responding to touch. Any ideas on this one? I’ve searched online, and I haven’t found anyone else with this issue.
    Best regards.

    • Bryon Thomas

      Have you tried a hard reboot, disconnecting the screen from the power source by tilting the screen out of the wall mount holder? If the problem persists, you likely have a hardware problem and require replacement.


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