#1 Best Seller: Nest Thermostat 3rd - Check Price Now! ( Works with Alexa )

Lux Products TX9100U Universal 7-Day Programmable Thermostat Review

The Lux TX9100U’s design and features offers all the advantages of a programmable thermostat. Your house heating system can be smartly operated by only drawing power when necessary, helping you save money on energy bills, as well as being eco-friendly.

Here is for an in-depth review and lay out of all the features, as well as the pros and cons of this thermostat, so you can decide if this model is the right option for you.

Top Features

The Lux TX9100U model, unlike many of their more modern programmable counterparts, does not offer cutting edge technology like wi-fi connection or geofencing. But that don’t mean that this model can’t be the best option for you.

The main features of the Lux TX9100U model includes:

  • ​Universal compatibility for all system types, unless they are electric baseboards.
  • ​Easy to install and operate, as it allows individual programming of each day of the week, with 2 or 4 heating periods a day.
  • ​The light one touch display gives all the essential lectures and shines in the dark, allowing programming with ease.
  • check
    ​The design is mercury free and comes with a default cycle that allows you to save up to $500 a year in energy bills.
  • check
    ​The keyboard can be secured from unauthorized access, meaning that if you have kids around, this can be a great security option.
  • check
    ​It comes with a vacation hold mode, meaning that if you’re out of your house for many days, you don’t have to worry about the unnecessary usage of energy from your system while you’re gone.
  • check
    ​It reads temperature with extreme accuracy which gives you a lot of reliability and security.
  • check
    ​It comes with a programmable air filter life timer that allows the stopping of pathogens and polluted free air from coming into your house.

​Being under $50.00, its price is quite affordable and is a pretty good investment that makes up for the amount of energy and money you would otherwise have spent over the years.

​Pros and Cons

​Overall, the Lux TX9100U offers all the features of a basic programmable thermostat, but unlike many other high-tech enthusiastic gadgets, this one has just enough features and guarantee to do its job exceedingly well, as it is highly accurate and built to last.

The specific pros of this model include:

  • ​Being compatible with almost every North American heating/cooling system, unless they draw power from electricity.
  • ​This model does support both single and multistage heating/cooling systems.
  • ​It only costs a ⅓ of the price of its more modern wi-fi enabled counterpart.

On the contrary, there are not that many cons outside of this being an even more basic design unit than the TX9600TS, so that what you see is all you’ll get with this.

​The cons of the TX9100U include:

  • ​Just like the TX9600TS it has the limitation of not being compatible with heaters that function under electrical power.
  • ​Lately, there seems to be an issue involved with the “lo Batt” sign being constantly shown even after buying brand new batteries. Because this is solely a battery-operated system, an error of this nature keeps the thermostat from running. Therefore, you need to keep an eye on that.

amazon check price button

Instruction and Installation

Of all the Lux thermostats, the TX9100U is the easiest to install.

Basically, all you need to do is to remove the previous thermostat and wire the cables according to the wiring diagram that comes in the user manual. Finally, you put the batteries in, attach the thermostat to the wall and you’re done.

Nonetheless, one thing that you should keep in mind is that you need to keep an eye on the wire setup, so you can properly label and connect the wires to the platform.


There are times where a series of factors can lead to the thermostat to malfunction and shut off.

That’s why we went through the official TX9100U troubleshooting manual to list some of the main issues that might affect the temperature regulations of the model, along with possible resolutions that can help to figure out these issues.


​Make sure to

  • ​Fan goes off in heat mode
  • ​Can’t remove the default programming

Scan the user manual for the setup options as the tree different revisions of this unity vary on the change of the setup options.

Fan will not turn off

  • arrows
    ​Move the Fan switch from On to Auto
  • arrows
    ​Remove ‘G’ wire, if fan still running, the system might be miswired or the heat/cool system is failing.

Misread temperature

​Scan the user manual to confirm correct set temperature. The “SET” sign should be displayed on screen

Second stage or AUX heating is not found

  • arrows
    ​Ensure the offset is set to 1 instead of 0
  • arrows
    ​Go to wiring diagram to verify correct wiring

Emergency heat won't turn on

  • arrows
    ​Must be set from Furn to HP
  • arrows
    ​Scan the user manual for the setup options as the tree different revisions of this unity vary on the change of the setup options.

Heats or cools more than 5 degrees past its displayed set temperature

  • arrows
    ​Remove thermostat from the wall and just leave the back plate. Verify healing and cooling are turned off in a couple of minutes.
  • arrows
    ​Replace batteries with Duracell or Energizer alkaline batteries.
  • arrows
    ​Setup heat mode. Adjust temperature at least 5 degrees below room temperature.
  • arrows
    ​Decrease the unit swing setting to a more narrow setting
  • arrows
    ​Know that in Cool Mode, thermostat may not activate a cooling stage until the compressor protection time is up

​(this may take up to 5 minutes)

​No heat/cool when expected

  • arrows
    ​For Heat Pump systems, ensure that the thermostat is configured for HEAT PUMP (HP mode) instead of Furnace (FURN) mode.
  • arrows
    ​Scan the user manual to confirm correct set temperature. The “SET” sign should be displayed on screen

Bottom Line

In short, the Lux TX9100U thermostat is a basic, highly compatible and easy to operate model, that is very inexpensive and provides all the necessary features that allows you to save a big amount of energy throughout the years.

However, even though most of the time the model seems to perform very well there can be some issues with the battery. If that happens make sure to immediately contact Lux customer support so they can help you out with any issue you might have.

Leave a Reply

Your email address will not be published. Required fields are marked *

Pin It on Pinterest

Share This

Share this post with your friends!