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LUX

Lux Pro P621U-010 Programmable 5-1-1 Day Thermostat, 2 Heat, 1 Cool, Batteries Included

  • Based on 35 reviews
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Availability: Only 3 left in stock, order soon!
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Arrives Thursday, Aug 6
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Style: P621U (5-1-1)


Features

  • Install easily in either horizontal or vertical orientation for versatile placement options
  • Includes easy-view backlight for clear display and operates on 2 included AA alkaline batteries for convenient, reliable power
  • Choose between Fahrenheit or Celsius temperature display options for your preferred unit of measurement
  • Tailor your comfort with adjustable temperature swing settings, featuring 9-step control for precise temperature management

Description

The LUX philosophy is a simple one: Design our products around you, making your life easier and more comfortable.

Brand: LUX


Model Name: P621U


Controller Type: Push Button


Special Feature: Universal compatibility for conventional heat & A/C. Universal compatibility for heat pumps with up to 2-stage heat/1 stage cool (including AUX/EMERG heat). 2 and 3-wire hydronic systems (hot water baseboard & radiator). Gas Millivolt heaters (wall heaters/furnaces & gas fireplaces) See more


Color: White


Controller Type: Push Button


Additional Features: Universal compatibility for conventional heat & A/C. Universal compatibility for heat pumps with up to 2-stage heat/1 stage cool (including AUX/EMERG heat). 2 and 3-wire hydronic systems (hot water baseboard & radiator). Gas Millivolt heaters (wall heaters/furnaces & gas fireplaces)


Specific Uses For Product: Air Conditioner, Heat Pump


Temperature Control Type: programmable


Power Source: Battery Powered


Voltage: 24 Volts


Display Type: LCD


Control Type: Button Control


Control Method: Touch


Mounting Type: Wall Mount


Backlight: No


Number of Batteries: 2 AA batteries required. (included)


Color: White


Shape: Rectangular


Product Style: P621U (5-1-1)


Material Type: Plastic


Brand Name: LUX


Model Name: P621U


Included Components: P621U-010 Programmable 5-1-1 Day Thermostat


Model Number: P621U


UPC: 021079126217


Global Trade Identification Number: 17


Manufacturer: EME Americas Inc.


Unit Count: 1.0 Count


Item Type Name: Diversitech 675-P621U Thermostat, 5-1-1P, NP, 2H/C


Manufacturer Part Number: 675-P621U


Item Weight: 0.11 Pounds


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Thursday, Aug 6

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

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Top Amazon Reviews

    • Reliable inexpensive and flexible option. Easy to program
Style: P621U (5-1-1)
I've been using Lux thermostats since 2009, when I bought my TX1500E, a model they no longer make, but have replaced with something similar, the TX1500RU (or something like that) Unfortunately, that one wasn't quickly available so I selected the P621U as a near-equivalent. The TX series uses exactly the same back plate, so no rewiring would have been required. Alas, it was not to be. The more readily available P621U-010 is similar in capability with the TX1500E, but has a slightly different form factor. Therefore the back plates are not interchangeable between the two models. Good news is that the footprint on the wall is the same, as is the mounting screw hole configuration. So, as long as your connecting wires are not super short, you'll be fine with a direct physical swap of the two entire units. The entire install, including removal, relocate, wire swap and programming of the new t-stat required less than 25 minutes, including clean up. it is an easy job. The directions provide clear well defined wiring schematic renderings for each of the possible system configurations. You will need to know which yours is. Because I was doing a straight swap, mine was super easy - with a wire-for-wire swap out. The Lux diagrams use standard class 2 wiring color schemes for the wires in question, so as long as your system is wired properly with typical class 2 wiring colors properly installed by your HVAC installer, you're good to go. Lux goes one further and explains what the wire DOES - not just "use white" or "use blue". So, if your colors are messed up by a bad install, you can still figure out what is what from how they're connected on the business end at your unit. This is a good feature in the directions and gets an extra kudo from me (speaking as a tech-savvy person with an EPA HVAC certification.) The programming of this unit is straightforward and intuitive. Being familiar with the Lux family of thermostats, I was able to move directly to programming - which was functionally exactly the same as programming my sixteen year old Lux TX1500E. This too is an admirable behavior by this manufacturer, and also deserves mention. Keeping programming "boring" and "the same" may not make the marketing wonks happy, but it definitely serves the end user very well. Extra kudos to Lux for this decision. Tell your marketing wonks to go have a conference or something... :-) The quality of this unit seems fine. The backlight blue display is clear and easy to read, and makes logical sense. It is identical to my other two Lux TX series in appearance, and both of them have remained bright, sharp and fully functional for sixteen years. Some logical improvements were made on this design. In particular, certain primary function buttons are moved out front and center - independent of the cover, a slight improvement over the TX1500E. Once programmed you probably won't have to open the cover except for extraordinary reasons like resetting the filter reminder, etc. The unit also features a "Setback" function, something the TX1500 lacked, and which I find handy. It is a primary button, accessible at all times. Physical wiring was fairly straightfoward - however be aware that the quality of the screw terminal strips securing the control wires is a little lower compared to the older TX1500E series. It is not terrible, but it is just not as sturdy. In particular, the screws themselves have a poorly selected cross-type head (aka "phillips") profile. Now, I am a tool guy, and I pride myself on the quality and breadth of my screwdriver selection. I have about anything you might imagine and a lot of weird stuff most folks don't know even exists. Besides every Phillips profile known to man, and JIS standards, I have other stuff, like Reed Prince, Torx, MorTorq, Tri-screw, Pentalobe, Frearson, Pozidriv, and a lot of other weird types you've never heard of. That said, I struggled to find a screw driver profile from my vast collection that really felt 100% accurate and secure in this device's terminal strips. I finally settled on a #1 Phillips as the best compromise...but even it wasn't that great. In addition the engagement slots for the wires are shallow and dead ended, which means you will likely need to trim your bare wires from the typical 5/8" strip-back typical of these installs. Because the strips themselves are a bit flimsy, it felt riskier than usual to apply enough push to keep the badly profiled screws from stripping out at the drive point. I didn't strip them, but they just did not feel anywhere near as good as the old TX1500 terminal points. But in the end, these are minor quibbles. The t-stat works well, it mounts quickly and easily and works flawlessly. Based on the sixteen year service life of my last Lux thermostat, i'm confident this one will go the distance. FWIW, my last thermostat failure was the mechanical relay that controlled the 24V signal to the unit. I could have replaced the relay, but chose to replace the entire t-stat, for the sake of time. This unit uses a physically smaller relay, so only time will tell how well it will hold up to repeated cycling. The previous relay used a pair of snubber diodes to manage contact arcing - perhaps this one does as well? I didn't disassemble it to see. FIve stars - recommended if you need a good basic easy to program 5+1+1 t-stat with filter function and system flexibility to work with conventional single and two stage package units, split systems, heat pumps, and the like. ... show more
Reviewed in the United States on October 29, 2025 by Ockham
    • Easy to install
Style: P621U (5-1-1)
My husband is super happy about this product. Easy to follow set up instructions. Value for money also well.
Reviewed in the United States on November 19, 2025 by ShopOnlineGi
    • Fit great
Style: P621U (5-1-1)
Fit great and was easy to install. Easy wiring too. I left any programming to others though.
Reviewed in the United States on January 27, 2026 by Ed Roberts
    • Some Like It Hot
Style: P621U (5-1-1)
Great bang for the buck excellent product easy to install no problems using or setting you will not be disappointed
Reviewed in the United States on November 12, 2024 by Big D
    • Not worth the trouble
Style: P621U (5-1-1)
I was having problems with my Honeywell and from the reviews decided to try this. After programming, which I thought I did correctly, my AC wouldn't shut off for 24 hours-this was not during the heat wave either. OK. Went back to manual to reset and figure out some more functionality. Not being able to find my answers ot understand what functions I had, I contacted the company. Turns out the manual both received and online were not updated. So rather than relying on tech support to get me through it I returned and went back to Honeywell. Now Im a happy customer! ... show more
Reviewed in the United States on June 24, 2025 by Cindy Essenmacher
    • Good value
Style: P621U (5-1-1)
I bought this to replace a malfunctioning thermostat. Good basic electronic thermostat. You can set uo to four temperature changes daily. You can also hold or override a setting. There are a couple more features I have not explored yet.
Reviewed in the United States on April 22, 2026 by Bob
    • No match heat pump
Style: P621U (5-1-1)
No match heat pump system
Reviewed in the United States on July 15, 2026 by Shu dui xie
    • Great Replacement for an Old Thermostat
Style: P621U (5-1-1)
Needed to replace an old thermostat that was not programable but wanted to also match the size of the existing "dumb" thermostat. This thermostat did the trick. It was easy to install and easy to program.
Reviewed in the United States on October 15, 2025 by Christopher D. Tucker

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