Budget Friendly Lux Geo Thermostats

Review: LUX Geo smart thermostat (GEO-WH-003 / GEO-BL-003)

Our Lux Geo rating:

January 2021 update: Heads up! This review was originally written in 2016. Many users are reporting that a recent update to the app has reduced and removed functionality from this thermostat. For a thermostat that works without a C-wire, take a look at the Emerson Sensi.

Lux Geo at a Glance

Lux Geo is a fully featured, WiFi-enabled smart thermostat that works with or without a C-wire… at a price point that barely makes a dent in your wallet. And it comes in two colors!

The affordable alternatives to Nest and Ecobee just keep getting better. The Lux Geo lacks a touch screen, but that’s about the only “smart thermostat” thing missing from this affordable and slick-looking WiFi-enabled thermostat.

Control it from an easy to use app, set up schedules with ease, and then take the whole family out to dinner with the money you save. Best of all, this is one of those rare smart thermostats that can run without a C-wire.



  • Sweet price point
  • Easy to program from unit or mobile app
  • C-wire optional! There are 3 ways to power it:
    • 24VAC (C-wire)
    • 2-AA lithium batteries (included)
    • Micro-USB (cable not included)
  • Intuitive wheel on thermostat itself makes it easy to adjust the temp
  • 7-day programming
  • Works with or without WiFi 
  • 2 or 4 periods per day
  • Huge temp display on-unit is always displaying, no need to “wake” it up
  • Adjustable temp swing range
  • Temperature alerts (too high / too low)
  • Mount it horizontally or vertically
  • Geofencing feature (optional) for hands-off savings
  • Air filter monitor
  • It comes in black and white! It’s pretty much the only WiFi thermostat with a body color choice.


  • If you run it on battery, you’ll need to feed it new batteries once in a while. Fortunately, it has a battery indicator to remind you when the time is coming. The manufacturer doesn’t really say how long a set of batteries should last, but they do say you must use lithium batteries. Fortunately, it comes with 2 lithium AA-size batteries to get you started.
  • No Amazon Echo “Alexa” support
  • No IFTTT support
  • It’s rather thick at 1.5″ which is normal for smart thermostats but it’ll probably project more than your existing thermostat

Lux Geo Thermostat Review

Two key features set the Lux Geo apart from the competition, both budget and high end: the options for powering it and its geofencing feature.

It works with or without a C-wire

Lux Geo is practically the only smart thermostat on the market that lets you power it with Lithium batteries in lieu of a C-wire. Feed it 2 AA Lithium batteries and watch it go – for months – before you need to replace ’em.



You can also power it via Micro-USB, but I wouldn’t power it via Micro-USB in the long run. The wire running from the thermostat to the USB outlet is just going to look sloppy, even if you have an outlet with integrated USB or an outlet with a USB wall adapter plug near the thermostat.

Radius geofencing

Geofencing is the other remarkable feature on the Lux Geo (get it, Lux Geo?). Geofencing is a relatively rare feature for a smart thermostat. The poorly received Honeywell Lyric is the only major smart thermostat on the market making a big deal out of geofencing, and a lot of people hated Honeywell’s implementation of it.

Note that you do not have to use the geofencing feature if you get a Lux Geo.

How geofencing works

When you are (or at least, your phone is) in the pre-defined radius, the thermostat turns up the heat or AC. When you’re outside of that radius, the thermostat uses a more energy efficient temperature (letting the house cool a bit if it’s heating season, letting the house warm a bit if it’s AC season).

Most reviews on Lux’s implementation of geofencing are positive, and relying on geofencing can be a great way of dealing with a coming and going schedule that’s difficult to program into a repeating 7-day calendar. You can set it up to read the position of multiple phones.

Setting the geofence radius via Lux Geo’s app

HVAC Compatibility

Lux Geo works with

  • Conventional heat & A/C up to 2-stage heat/2-stage cool
  • Heat pumps with up to 2-stage heat/2-stage cool (including aux/emergency heat)
  • 3-wire heat only hydronic systems (hot water, baseboard and radiator)
  • Gas millivolt heaters

Lux Geo doesn’t work with

  • Doesn’t work with a heat pump with (Y2) two compressor stages
  • Doesn’t work with line voltage systems (120/240 VAC)

Two possible orientations

This is the only smart thermostat I’ve seen designed to be mounted either horizontally or vertically. The screen has to be on the top if you mount it vertically.


Depending on how much space you have for your thermostat, you might find this feature useful!

Lux Geo mounted in “vertical” orientation

More cool Lux Geo features

Supports multiple zones in one house, and you can access them all in one app.

Supports multiple Lux Geos in multiple homes (on different WiFi networks), which is good for keeping an eye on vacation homes and elderly family members.

Control from mobile (iOS/Android) app or the web portal through your computer.

Lock the controls on the thermostat so no one can mess with your temperature settings.

Automatic daylight savings adjustment because everyone hates reprogramming their thermostat twice a year.

Recommended energy-efficient settings so you don’t have to guess. You can put in your own preferences, of course, but if you’re not sure where to start, the Lux Geo app has a collection of “energy profiles” to pick from, ranked by efficiency.


You can customize how long the thermostat’s screen stays lit. Keep it constantly on or tell it to automatically turn itself off in 5-15 seconds.

Detailed statistic reports! Usage reports are surprisingly rare among smart thermostats, but the Lux Geo generates fairly detailed reports.

Geo Lux tech specs


  • 5.8″ wide x 3″ tall 1.5″ thick

Power options

  • 24VAC (C-wire)
  • 2-AA lithium batteries (included)
  • Micro-USB (cable not included)

More Lux Geo resources

Promotional video showing off some of Lux Geo’s best features:

The bottom line


If you don’t need a trendy design and aren’t sold on room temperature sensors, the Lux Geo smart thermostat is absolutely the way to go.

You won’t miss a thing – in fact, you might features you won’t get at this price point (or in such a well-designed thermostat), such as geofencing.

Lux Geo vs. Emerson Sensi

Compared to its closest price and feature competitor, the Emerson Sensi, the Lux Geo is really just missing a couple things: support for Amazon’s Alexa “voice assistant” service and tighter control over the day’s schedule (Sensi lets you schedule as many temp changes in a day as you want, while the Lux Geo seems to limit you to 4 scheduled adjustments per day). The Sensi also has more on-unit buttons, which we think is slightly easier to use than the rotate-and-press wheel design on the Lux Geo. If those things are important to you, go with the Sensi.

If they’re not important to you, or your system is heat only and lacks a C-wire or you want the usage reports, go with the Lux Geo. You can’t go wrong with this budget-friendly smart thermostat.

See the Lux Geo’s current stock and price on

Lux Geo in white

Lux Geo in black


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12 replies on “Review: LUX Geo smart thermostat (GEO-WH-003 / GEO-BL-003)”

I think this is a good thermostat for the money, but I’m kind of annoyed that there isn’t an option to completely hide the USB cable. Has anyone tried dismantling the thermostat and soldering the 4 wires needed for the USB connection directly to the board where the micro USB connector attaches?

Reviews often remark on the “dated” design. I am shopping for a thermostat that I can control for an aging parent that has made a disaster out of touch screen thermostats due to not being able to understand how it all works. Managed to set the calibrated temp down to 53 and when I got to the house it was freezing in there despite the display saying a toasty 72. This simple wheel design and LCD display that is not touch controlled is precisely a fantastic thing for older non-tech people aging in place. Planning to buy one so at 11 pm on winter nights I can ensure mom does not do something wonky and sleep in 85 degree or 50 degree temps – and sounds like I might also be able to get notices of power out, heat/cool not kicking on for x period of time. This design seems FANTASTIC for older folks… simple dial they just turn up or down. She also will turn the fan to ON and not have the heat on and think it is heating and keep turning up the thermo because the fan is running. This unit seems to solve that too. Hope it works good!

I’ve been using this great, smart thermostat for several years now to control our Viessman boiler and it is perfect. We had an (unused) C wire so installation was easy. We didn’t want touch screens — just an easy to read screen and the dial/button is foolproof. The clean design is unobtrusive and the wifi control lets us turn on the heat before arriving home.

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