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Availability:
Only 7 left in stock, order soon!
Arrives
Tuesday, Sep 29
Size: 3.5H x 4.75W x 1D (in.)
Style: Thermostat
Features
- ONE WEEK PROGRAMMING: Set one identical program for the entire week with four program periods per day including wake, leave, arrive and sleep.
- PRECISE TEMPERATURE CONTROL: Precise temperature control of plus/- 1 degree Fahrenheit
- DIGITAL DISPLAY: Easy-to-read digital display with an intuitive interface for one-touch access to setpoint temperature
- EASY INSTALLATION: Easy to install yourself and basic operation keeps programming simple
- REMINDERS: Built-in battery change reminders (2 AAA batteries are required for operation)
- SET POINT RETENTION: Set point is retained in memory in the event of a power outage
- DISPLAY OPTIONS: Fahrenheit or Celsius; 12 or 24 hour clock. Note: This thermostat is not backlit.
- OVERRIDE OPTIONS: Permanent and temporary override capability
- COMPATIBLE WITH: Heating, cooling and heat pumps without auxiliary heat options
- Does NOT work with electric baseboard heat (120-240 V), heat pumps with backup, or multi-stage heating/cooling. For indoor use only.
Description
This easy-to-operate 1-Week Programmable Thermostat helps make your home comfortable exactly when you want it. Programmable for one week, it lets you customize your schedule with four options – ‘wake’, ‘leave’, ‘return’, and ‘sleep’ – for precise temperature control and added comfort. Simple step-by-step instructions included with the thermostat make DIY installation easy. From the Manufacturer A Honeywell programmable thermostat can save you significant money off your energy bill. You set it up to adjust the temperature when you are away or asleep---times when you don’t necessarily need to heat or cool your home to optimum comfort---and your heating and cooling equipment runs less. This one-piece thermostat has one easy program for all days of the week (4 periods - wake, leave, return, sleep). Simple and effective use and performance.
Brand: Honeywell Home
Model Name: RTH221B
Product Dimensions: 1"D x 4.75"W x 3.5"H
Controller Type: Hand Control
Special Feature: Clock Display, Low Battery Indicator, Low Voltage, Programmable
Controller Type: Hand Control
Additional Features: Clock Display, Low Battery Indicator, Low Voltage, Programmable
Specific Uses For Product: Air Conditioner, Furnace
Temperature Control Type: Heating and Cooling
Connectivity Technology: Non-connected
Power Source: Battery Powered
Voltage: 24 volts
Display Type: Digital
Control Type: Button Control
Control Method: Touch
Mounting Type: Wall Mount
Number of Batteries: 2 AA batteries required.
Color: White
Shape: Curved
Product Style: Contemporary
Material Type: Plastic
Finish Types: White
Brand Name: Honeywell Home
Model Name: RTH221B
Included Components: Mounting Hardware, Thermostat, User Manual
Model Number: RTH221B1039
Manufacturer Warranty Description: 1 year limited.
UPC: 085267348553
Global Trade Identification Number: 53
Manufacturer: Honeywell
Number of Items: 1
Item Type Name: Programmable Thermostat
Manufacturer Part Number: RTH221B
Item Dimensions D x W x H: 1"D x 4.75"W x 3.5"H
Specification Met: energy
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Tuesday, Sep 29
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.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
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Top Amazon Reviews
I can't believe I waited so long to replace the old mercury bubble thermostat on my hot water heat system. I noticed a friend had a new one, so I decided it was time to do some research here at Amazon. I wanted a vertical style to match the placement of the old one which narrowed the field considerably. I wanted a simple day/night setback and didn't need separate settings for weekends. I wanted simple controls and ease of temporary adjustment. This one fit the bill perfectly. Installation was a breeze. The instructions are clear and easy to follow. My two-wire system connected to the Rh (Red - heat) and W (White) terminals. The wires weren't that color (probably the original 90 year old wires!) so I either guessed right or, more likely, it would have worked if they were reversed since it's simply an open/close switch to activate the heater. I even reused the mounting screws from the old unit - sweet! Stop by your local Dollar Store and pick up a mini screwdriver set if you don't have one. Programming is straightforward, and again the instructions are clear. It comes preprogrammed with four periods - Wake, Leave, Return, and Sleep. It's easy to adjust these to your desired time/temp. I skipped two of them completely by simply pressing the Hold button for four seconds while that period was displayed during setup. Believe me, you'll be tweaking your settings with abandon after the first run-through... it's that easy. I love the simplicity of the display. What's the current temp? Look at the screen. You're a bit cold? Tap the up arrow once and read the setpoint; tap it again to temporarily raise the setpoint one degree, again for two degrees, etc. The unit will retain your temporary setting until the next programed change (e.g. night setback) or until you press the Run button. Going away for a couple of days? Tap in the desired setpoint and press Hold. Simply press Run again when you get home. As noted in other reviews, there is no backlight in the display. You can download the installation and user's manual at the Honeywell website to get a peek at how it works. Be sure to note the Configuration Menu in the installation instructions. I had to change the "Heating Cycles per Hour" setting to "3" (for my hot water system) from the default "5" setting. What is Heating Cycles per Hour, you ask? It's a means to fine-tune the efficiency of the system's attempts to maintain your desired temperature. It's ONLY active when you're within a degree or so of the setpoint temperature. Here's how it works: Say, your setpoint temperature is 70°. As the heater brings the room air temp up towards the setpoint, an anticipator circuit cuts off the heat at a predetermined value, say 69° to keep from overshooting your requested 70°. Ideally, the residual heat from your burner/blower/fan/radiator will gently nudge the air temp up to 70°, and all is right with the world. So far we have: temp below 69°, run heater; temp above 70°, stop heater. But what happens between 69° and 70°? What if there wasn't enough residual heat to get to 70°? Or what if your furnace isn't sized properly, or your insulation is weak, or the kids left a window open? Where's that 70° you requested? This is where you heater starts cycling. My "Cycles per Hour" is set to 3, which means 3 twenty minute cycles each hour consisting of 10 minutes OFF, 10 minutes ON. When the air temp hit 69° the heater stopped for 10 minutes, hoping the air temp will reach the magic 70°. 10 minutes later it takes a peek at the temp... 70° or above? Great! Job done. No cycling involved. Oops - only 69.3°? - start up again for 10 minutes, shut down, wait 10 minutes and check again. 69.8° this time? Start up again for 10 minutes and another cycle. This time, let's say the temp hit 70° after 8 minutes of heat. Great! - job done, shut off heat and stop cycling. It might overshoot to about 70.3° this time - well within your comfort zone. Now, sit warm and cozy in front of the TV as the temp slowly falls from 70.3° to 69° and listen for the cycling to begin again. If you're well insulated, it's a fairly mild night, and your heater is sized properly, it might go through a cycle every couple of hours. If there's a blizzard blowing outside your poorly insulated shack, it might cycle on and off every 10 minutes, or even stay on constantly if it can't get you above 69°. To recap: Temp below setpoint minus one: heater ON. Temp above setpoint: heater OFF. In between: cycle ON and OFF in attempt to efficiently get to setpoint without too much overshoot. Why? A heater is more efficient running longer cycles rather than rapid On/Off cycles. A heater with a lot of "thermal inertia" - like my hot water system, takes a while for those warm radiators to gently get the air temperature to the desired setpoint... it needs cycles a bit longer to be efficient and effective. A rapid heat system, like an electric wall heater, will get that air temp up quickly - it needs a higher cycle rate / shorter 'burn' time to stay efficient and avoid overshoots. In fact, the cycle rate for electric heat is 9: that's 9 cycles of 6.7 minutes per hour. Air conditioning cycle/hour is fixed at 3. One more thing: if you want the fancier model, the Honeywell TH2110D1009 is the same unit, but with backlight, 5/2 day programming, and something called "Adaptive Intelligent Recovery" which learns how fast your heater gets you to your desired temperature so that you can program it to BE at a given temperature at a given time... handy for those early morning middle-of-winter wake ups! Be sure to properly dispose of that mercury! Enjoy!
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Reviewed in the United States on March 1, 2010 by Ike Bike
I purchased this programmable thermostat to install in the portion of my two-family home that I live in. I also purchased the similar Honeywell RTH111B Vertical Digital Manual Thermostat NON-programmable model for the portion of my home that I rent out. Installation of both models is identical, and the main difference between the two is just the ability to set up a program of varying temperature changes based on your schedule. The non-programmable RTH111B has no clock feature. Just simple buttons to change the temperature up or down, and switches for a system fan (if applicable) and the HEAT-OFF-COOL selection. The programmable RTH221B gives you these same features, PLUS a 7-day, 4-event schedule to work with. In other words, every day of the week is treated the same and you can program in a time and temperature change for waking, leaving, returning, and sleeping. For people who desire to have a different schedule for the weekend, a 5/2 day programmable model would be a wiser choice. The apartment that received the RTH221B is a simple heat-only, oil-fired steam radiator system. The installation instructions were generally easy to follow, but I also found additional information on the Honeywell website explaining what each terminal actually was. It would have been useful for Honeywell to print this in the instructions. Summarized: Rh : Heating power supply Rc : Cooling power supply W : Heating signal Y : Cooling signal G : Fan Both of the two environmental systems in my home are ONLY heat, and have a two-wire connection. The wiring looked about a hundred years old, but still worked perfectly once I connected the wires to the Rh and W terminals. Interesting to note that in both installations it did not seem to make a difference which of the two wires went to what terminal, so long as it was Rh and W. However in a more complicated system that includes more wires for cooling or a fan, I'd use the included labels to mark each wire and be certain it was connected properly. Following the instructions, setting up a schedule for temperature changes was a simple process. Even if you ONLY wished to alter the temperature at night (rather than during the day while at work), it's a breeze because you'll just set the temperature the same for the "leave" and "return" events. Overall, setting the clock and programming took only a couple of minutes. I don't have any dollar amount savings to offer, but I can say that the temperature was MUCH more consistent in my apartment than it had been with the old round-style mercury switch which was prone to large temperature swings. There is no question in my mind that less fuel was used, and it's very likely that the two thermostats I purchased have already paid for themselves one month later.
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Reviewed in the United States on February 26, 2011 by Eli Anderson
Size: 3.5H x 4.75W x 1D (in.)
Style: Contemporary
This thermostat does exactly what it’s meant to, keeps your home at a comfortable temperature without any complicated setup. Installation was quick and straightforward, even for someone who’s not super handy. The instructions were clear, and it powered right up once connected. The display is easy to read, and the programmable feature is great for setting different temps during the day and night. It’s not fancy or smart-home compatible, but that’s also what I like about it, fewer buttons, fewer issues. Once set, it keeps the temperature steady and accurate, and it’s easy to adjust when needed. If you’re looking for a no-frills, dependable thermostat that just works, this one’s a solid choice. Pro tip: double-check your wiring before installing, it makes the whole process even smoother.
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Reviewed in the United States on October 8, 2025 by Denisse Villar
I carefully read many reviews before ordering two of these thermostats. My biggest concern was the accuracy of the units, and I was not disappointed. Before mounting them, I checked that the temperature readout was accurate by placing them next to a reliable source, and they all read exactly the same. After mounting them, I see that there appears to be a slight error, but I’m confident that the problem is that the wall which the thermostat is mounted on is not heating up as fast as the rest of the room, rather than blaming it on the thermostat. After one week, I’m very satisfied with the overall performance. Mine is operating a zoned hydronic system, and only requires a red and white wire to operate. One confusing portion of the program is the cooling cycle. I found that by simply placing the program in “heat” is all that is required; just ignore the “cool” portion of the program and everything works fine. The units are fairly easy to program, and even easier to over-ride. By simply pushing the “up arrow” it’s easy to adjust the current setting to any desired temperature, which stays in effect until the next programmed time cycle kicks in. The biggest downside with these units is that they are only programmable for one day, which repeats every day. But considering the cost and “programmability” of a 7 day thermostat, I think this unit is a bargain. Once the thermostat program is understood, it’s very easy to re-program any portion of the cycle. I give it 5 stars considering the price and simplicity of use, and its effectiveness over a non-programmable thermostat. My only piece of advice is that if anyone has a very consistent schedule that varies from weekdays to weekends, and does not change from week to week, then they might consider upgrading to a more expensive 7 day programmable thermostat.
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Reviewed in the United States on February 13, 2013 by Andyman
Size: 3.5H x 4.75W x 1D (in.)
Style: Contemporary
Pretty straightforward. Depending on the type of Heat and/or AC that you have will depend on how you wire it. The instructions in the box give you the needed info to wire it to the proper style as well as program it as needed. As long as you read the instructions as you install it, you'll be fine. There are a few styles of system that it will NOT work with, but those systems are listed in the item description, so make sure you read before purchasing..... I have a heat only 24VAC baseboard water heat system and a 2 wire connection and it works perfectly fine. Again, as long as you confirm your system is compatible prior to purchasing and then read the instructions BEFORE miswiring something, you'll be fine. The programming options are a 7 day schedule, so you can not set something different for weekday vs. weekend. It will have to be the same for all 7 days, though you can temporarily or permanently override the programming as needed. You can set 4 different programming slots in a given day; wake up time, leave house time, return home time, and sleep time. I've had it installed for a few days now and it's very straight forward. For the price you can't beat it.
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Reviewed in the United States on November 22, 2024 by Reviewer
Size: 3.5H x 4.75W x 1D (in.)
Style: Contemporary
The good side is that I don't have to program 2 or more days per week. I can just tell it what time of day I want a setting once, and done. If your household keeps different schedules on different days, you might want complicated. Our schedule reads, "There is almost always someone home." I previously had a thermostat (that I hated) that would take the time and temperature I entered, and try to get to that temperature by that time. This drove me nuts because I allow the house to run warm in the summer evenings during peak electric rates, and want to cool it for more comfortable sleep after the price goes down. With this thermostat, if I tell it to lower the temperature at the time the price drops, that is when it kicks in--not half an hour earlier during peak pricing. What I really don't like about this thermostat is how hard it is to open. I am always thinking I'm going to break it, or maybe it is not supposed to open. When I stop to think about it, I know there has to be a way to get it fastened on the wall, and I'll keep tugging at it. Today, after having it for 2 years, without warning the screen went blank and the A/C kept cooling and cooling. After switching the system off, I got it open and changed the batteries. Yep, screen came back on! The temperature was all the way down to 70 F! I have left it off for now and will try to reprogram it later.
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Reviewed in the United States on September 5, 2026 by Miss Martha
Size: 3.5H x 4.75W x 1D (in.)
Style: Contemporary
This is an excellent thermostat. It was easy to install. What I had a problem with is whoever did the wiring for our house, left almost no slack in three of the wires that go into this thermostat. I struggled with that for what seemed like forever, tried hard to pull the wires out more, then succeeded in getting them in and tightened the screws. It came with labels for the wires, but it was a straightforward wire placement, exactly as my old thermostat, so I didn't bother with labeling the wires. My old thermostat was Honeywell, and this one is Honeywell Home. Now that I look back on it, years ago, I replaced the thermostat, and struggled with those stupid wires, too. Hopefully it will hold and the wires won't slip off. I put some flexible tape over the side of it to hold it up so the wires won't slip. Well, the red wire to be precise. Right now, though, it is icy cold in our house and my husband is happy. I will have to study the manual that came with it to figure out how to program it. The Honeywell name brand is a well respected one in home cooling and heating, and we just bought a tower fan in that brand. I am happy with this new thermostat and I would recommend it.
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Reviewed in the United States on March 24, 2026 by Elsie McNeill
Size: 3.5H x 4.75W x 1D (in.)
Style: Contemporary
Just a regular super simple thermostat that was easy to exchange and program. It’s a Honeywell that’s all I needed to know about longevity not some offbrand. You must know that this has to have batteries ( AAA and not included) to work! It will not operate without batteries! It is not powered from your furnace in anyway shape or form. There’s a little notification on there when it’s time for batteries, but I just change mine every six months and I never have to worry about it, same as my old thermostat. 20 bucks apiece I can’t beat that — you can buy the exact same at the big box store for more than double the price, I only had to wait about eight hours to get it to the house from Amazon. A+ These a little smaller footprint than the older version so sometimes you’ll need a little adapter plate that goes behind it just to cover the paint. It’s also a Honeywell product you can look it up on Amazon.
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Reviewed in the United States on July 7, 2024 by D