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Honeywell RTH221B Basic Programmable Thermostat

4.2 out of 5 stars 293 customer reviews
| 30 answered questions

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Estimate: $102.95
100% positive ratings (6 reviews)
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  • Plastic
  • Imported
  • All control buttons are on the face of the product with a display that shows current and set temperatures
  • Precise temperature control of +/- 1 degree F
  • Basic one programmable with four programmable periods per day
  • Vertical positioning for easy upgrade from standard manual thermostats
  • One-touch hold
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Product Description


Offering the ease and reliability of basic programming, the Honeywell RTH221B One-Week Programmable Thermostat can help save money on your energy bills--without sacrificing your comfort. Featuring a sleek one-piece design that blends seamlessly with any decor, the RTH221B is compatible with most heating and cooling systems.

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RTH221B One-Week Programmable Thermostat
At a Glance:
  • Basic operation keeps programming easy

  • 4 program periods per day

  • Precise temperature control of + /- 1 degree

  • For use with central gas, oil, or electric furnaces and AC

  • 1-year warranty
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Honeywell RTH221B One-Week Programmable Thermostat
Using a programmable thermostat is one of the easiest ways to reduce energy costs.
Precise, Programmable Temperature Control
The RTH221B lets you control the temperature inside your home, even when you're not there. In just minutes, you can create one simple program that will run for the entire week, with up to four program periods per day (wake, leave, return, and sleep).

For further convenience, the RTH221B gives you precise temperature control plus or minus one degree Fahrenheit, so you can create the atmosphere that's perfect for you.

Save up to 33% on Annual Heating Costs
Using a programmable thermostat is one of the easiest and least expensive ways to reduce energy costs and protect the planet--without sacrificing personal comfort.

By creating a program that automatically adjusts the temperature during times when optimum comfort is not necessary (e.g. when you're sleeping or away from home), you can significantly cut down on your overall energy usage and reduce your monthly bills. In fact, depending on your geographic region and usage patterns, the RTH221B can help you save up to 33% on annual heating costs.

User-Friendly, One-Piece Design
One of the RTH221B's key advantages is its user-friendly, one-piece design. All control buttons are visible on the front of the unit for quick and easy accessibility, and the display clearly shows current and set temperatures. Soft-touch/one-touch hold buttons keep things simple, while vertical positioning makes for an easy upgrade from standard manual thermostats.

Compatibility and Warranty Information
The RTH221B works with central gas, oil or electric furnaces, AC, and millivolt systems. It is not compatible with multi-stage heating/cooling systems, heat-pump systems, or electric baseboard heat (120 - 240 volts).

The Honeywell RTH221B One-Week Programmable Thermostat and is backed by a one-year warranty.

What's in the Box
Honeywell RTH221B One-Week Programmable Thermostat; mounting hardware; warranty card; and manual.

Single-Stage Heating and Cooling yesMultistage Heating and Cooling 
Heating OnlyyesCooling Onlyyes
Furnace (Warm Air) yes Central Air Conditioningyes
Heat Pump without Auxiliary Heat Heat Pump with Auxiliary Heat  
Hot Water yes Steam or Gravity yes
750 Millivolt yes Gas Fireplaces
(24 Volt or 750 Millivolt)
Electric Baseboard Heat
(120 - 240 Volts)

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.

Product Information

Technical Details

Part Number RTH221B1000
Item Weight 5.6 ounces
Product Dimensions 11 x 7.5 x 9 inches
Item model number RTH221B
Size Large
Color White
Shape Curved
Item Package Quantity 1
Display Style Digital
Batteries Included? No
Batteries Required? Yes
Warranty Description 1 Year Product Warranty
Assembled Diameter 1.1 inches

Additional Information

Customer Reviews
4.2 out of 5 stars 293 customer reviews

4.2 out of 5 stars
Best Sellers Rank #82,301 in Home Improvements (See top 100)
#178 in Home Improvement > Building Supplies > HVAC > Thermostats & Accessories > Thermostats > Programmable
#5,247 in Home Improvement > Contractor Supply
Shipping Weight 5.6 ounces
Domestic Shipping This item is also available for shipping to select countries outside the U.S.
International Shipping This item is not eligible for international shipping. Learn More
Date First Available August 17, 2005

Warranty & Support

Product Warranty: For warranty information about this product, please click here


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Customer Questions & Answers

Customer Reviews

Top Customer Reviews

By Miles H. Kennedy on December 20, 2007
Verified Purchase
My wife and I are both retired so every day is a 'weekend day'. Most thermostats require multiple settings for different kinds of days. Good idea if you're a worker but bad idea if you're me since going on vacation etc requires MULTIPLE thermostat adjustments. Also, why pay extra for annoying unused features. This thermostat is simple, easy to install and has typical Honeywell accuracy and reliability. For me it's ideal.
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I bought this thermostat this fall from a big box home improvement store and it's paid for itself several times over in a few short months (and I paid more than the listing price on Amazon).

I had never installed a thermostat before, but it was a breeze to install. I turned off the breakers to my living room, carefully removed the old thermostat, attached two wires, installed a couple of screws (I think that I ended up drilling one new hole), and turned the power back on. Less than 15 minutes from start to finish, and I'm not the handiest gal you'll ever meet. It worked. I set it to turn down at night while we're sleeping and during the day when we're gone. I also put the plastic on the windows, but other than the new thermostat I did nothing different this year than last.

February 2008- the portion of our utility bill for natural gas was $188.03. February 2009, with the average temperature just 4 degrees warmer, our natural gas bill was $88.08. We have saved at least $40 every month since I installed it. It's paid for itself several times over. It's probably the best thing I've purchased in a very long time.
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Basic programable t-stat. Works well, easy to install Honeywell is a good brand. **HOWEVER in picture on amazon the screen on it looks back-lit, but it is not lit.
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Verified Purchase
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.
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Verified Purchase
I bought 2 of these units. After letting them sit on the table next to each other for a while, they displayed different temperatures, by a difference of about 3 degrees. I was surprised they were that different. I considered sending them back, but instead I used them as they were. The temperature difference seems to have worked its self out and they do their job just fine. After using one of the Lux models a few years ago, I found myself wanting the extra features that it had (another mode for weekends). The display constantly shows the current temperature but unless you hit one of the up/down buttons, will not show you what the current thermostat temperature is set to. I found this annoying as my wife is constantly changing the temp on me and I would like to know what it is currently set at. The LUX model displayed both. If I had it to do over again I would have bought a different brand, probably Lux. Also, a horizontal model would have covered the round marking that my previous thermostat left.
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Verified Purchase
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.
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