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Honeywell Home

New! Honeywell Home Programmable Thermostat, Single-Stage, 1 Heat/1 Cool Compatibility, Flexible Schedule, X2P, White, RTH21B

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Availability: 11 left in stock
Fulfilled by Amazon
Arrives Friday, Apr 17
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Features

  • CUSTOMIZE: Choose to receive change air filter reminders, change out the decorative accent color with interchangeable white and gray accent pieces, and select display settings to optimize this thermostat for home. The RTH21B is a directly replacement the RTH2510, and replacement for the RTH2410 offering personalized programming of 7-day, 5-1-1 day, 5-2 day or 1 week schedule options
  • SCHEDULE: Personalize programming in 7 day, 5-1-1 day, 5-2 day or 1 week options - there's even a non-programmable option
  • EXPERIENCE: A large screen and clear font enhance daily use
  • INSTALLATION: The Honeywell Home UWP wall plate provides an easy install process and simplifies future device upgrades
  • FEATURES: Flexible scheduling, backlit display, custom display settings, change filter reminder, extended 32F low-heat setpoint, 1-year warranty
  • COMPABILITY: 1 Heat/1 Cool, 750 mV, hot water heat, forced air (gas, oil, or electric) [does not work with electric baseboard heat (120-240V)]
  • POWER: 2 AA batteries (not included)

Description

The Honeywell Home X2P Programmable Thermostat is optimized for single-stage 1 heat/1 cool systems. Its flexible scheduling technology allows personalized programming to fit your lifestyle in 5-1-1 day, 5-2 day, 7 day, or 1 week - there's even a non-programmable option. It’s a quality thermostat for your home that can be customized to receive change air filter reminders, coordinate with home decor thanks to the interchangeable decorative accent pieces (comes with white and gray options), and select display settings.

Brand: Honeywell Home


Model Name: RTH21B


Product Dimensions: 30"D x 8"W x 6"H


Controller Type: Push Button


Special Feature: Programmable, Flexible Scheduling, Change Filter Reminder


Brand: ‎Honeywell Home


Model Name: ‎RTH21B


Product Dimensions: ‎30"D x 8"W x 6"H


Controller Type: ‎Push Button


Special Feature: ‎Programmable, Flexible Scheduling, Change Filter Reminder


Color: ‎White


Specific Uses For Product: ‎Home Heating and Cooling Control


Temperature Control Type: ‎Programmable


Included Components: ‎Wall Plate, Temperature Sensor


Power Source: ‎Battery Powered


Item Weight: ‎13.12 ounces


Display Type: ‎LCD


Control Method: ‎Touch


Mounting Type: ‎Wall Mount


Style: ‎Single-Stage Compatible


UPC: ‎194159017368


Global Trade Identification Number: ‎66


Manufacturer: ‎Resideo


Smart Home Compatibility: ‎Smart Home Compatible


Part Number: ‎RTH21B


Item Weight: ‎13.1 ounces


Item model number: ‎RTH21B


Pattern: ‎7 Day Flexible Programmable


Item Package Quantity: ‎1


Special Features: ‎Programmable, Flexible Scheduling, Change Filter Reminder


Batteries Included?: ‎No


Batteries Required?: ‎Yes


Date First Available: January 7, 2025


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Friday, Apr 17

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

    • Great thermostat with a lot of options
Review Image by Elliot G. Elliot G.
Review Image by Elliot G. Elliot G.
Great thermostat!!! Lots of options and easy to install. Great value!! Love that there was a switch to have one red wire or two. Most thermostats have you cut the jumper if you wanted two or add a jumper. Lots of options. Wanted to program a single week, not 5-2 or 5-1-1. Easy to read screen and very accurate. Two things I wish it had. 1) bluetooth so you could change/program it from your phone 2) an external sensor to place somewhere else ... show more
Reviewed in the United States on January 21, 2026 by Elliot G. Elliot G.
    • Great Unit
Easy to install and easy to program. Works well
Reviewed in the United States on December 8, 2025 by SP
    • Keeps the house warm.
Easy to install and working great.
Reviewed in the United States on February 9, 2026 by mtalou
    • Works for my baseboard oil heat
Works great. Love the 7 day programming ability.
Reviewed in the United States on November 20, 2025 by Michael
    • Great 7-day programmable thermostat that doesn't require C-wire
Setup and programming is fairly straightforward, although you will have to use the manual during initial setup since it uses a numbering system for the menu options such as setting up conventional vs heat pump, gas vs electric, etc. It's well priced for the functionality, and I'd recommend this to anyone wanting a 7-day programmable, non-wifi thermostat, especially for those who don't have a C-wire (works with or without a C-wire). Feature highlights: Oddly, even if your system has a C-wire, it still requires 2xAA batteries for power Does not require a-C wire to function (I've tested and verified on systems with and without C-wires) Easy to mount Fan: On / Auto / Circulate Modes: Cool / Heat / Auto (auto must be enabled in setup menu) Has 4 settings per day: Wake / Home / Sleep / Away Can be used in manual mode and/or programmed with 7-day or 5/2 HVAC filter replacement reminder with lots of options such as time-running or time-period (ex: 30 days of runtime, or 30 days, etc) ... show more
Reviewed in the United States on July 17, 2025 by Tex
    • Simple to use- but sometimes turns on when not programmed to.
Overall- this works great. Easy-ish to install, easy to set up and easy to adjust. We purchased the 7day programmable- randomly (not consistently or even a pattern of days) it turns on at 4:30am to the preset time that is supposed to begin at 7:30am. This week it has done it on thurs/fri/sat. There is nothing set up for 4:30am and it does not come on every day at 4:30….just some days. But when your heat blasts to 68 at 4:30 and you have been sleeping at 56°- it wakes you up. Hoping this is an easy fix…will be calling the 800 number to see if they have answers. ... show more
Reviewed in the United States on February 21, 2026 by Alison Kaehn
    • Honeywell Great Thermostat
The Honeywell home thermostat is just what I was looking for to replace my old thermostat.I looked high and low, but finally found on Amazon. it’s made well, easy to install and gives me even heat through out my house. The price was pretty reasonable too. Once again Thank You Amazon for always carrying items that you can never find in nearby stores. ... show more
Reviewed in the United States on March 12, 2026 by Sallypecoraro
    • 7 day programmable is great
I was tired of getting cold on Friday nights and going to bed on Sunday when it was too warm in the house. I replace my 5+2 day thermostat with this 7 day one and am very happy. I also like the large numeral display.
Reviewed in the United States on January 19, 2026 by LeaveMeAlone

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