Programmable Thermostats

Reviews of digital programmable thermostats

Honeywell RTH221B Basic Programmable Thermostat

Click Here to find the Best Price on Amazon for the Honeywell RTH221B Basic Programmable Thermostat

List of Specifications:

  • 1 Week programming
  • 4 periods to set up – ‘wake’, ‘leave’, ‘return’ and ‘sleep’
  • Ability to skip periods
  • Temporary hold
  • Digital display (without back light)
  • Retains settings even after a power outage
  • 1 year warranty
  • Price about $22 from Amazon (click the link above to check the price on


  • Central air, heating only, cooling only, gravity/steam, 750 Millivolt, hot water, gas fireplaces
  • 1 stage of heating and 1 stage of cooling


The Honeywell RTH221B Basic Programmable Thermostat is a one week device that comes with a 1 year warranty. It is a vertical style thermostat that may suit the gap in the wall left by an old thermostat. Its simplicity might suit people who are retired or don’t need to set a different program for every day of the week. The cheap price of just over $20 might also suit people who want to upgrade from an old mercury bubble thermostat but who don’t want to buy an expensive thermostat with lots of functions they are never going to use.

In reviews of the Honeywell RTH221B many people comment that they bought the device because they didn’t want the hassle of setting up  lots of programs for each day of the week. The Honeywell RTH221B has 1 program with 4 periods of heating/cooling to set up. They are ‘wake’, ‘leave’ ‘return’ and ‘sleep’. If you are retired and every day is effectively the ‘weekend’ then the Honeywell RTH221B might well be the device for you.

The thermostat is compatible with heating only, cooling only, single stage heating, single stage cooling, furnace (warm air), hot water, 750 Millivolt systems, central air, steam or gravity and gas fire places. It cannot manage heat pumps.

It is a battery powered device that has a small display that is not backlit. It is simple to self-install if you read the instructions carefully. With all instructions you shouldn’t rely on the wires being colored correctly; instead, you must use the configuration from the old thermostat to help you determine the correct coloring of each wire.

As this thermostat only has 1 program to set up it is very easy to program. There are few buttons and few functions to confuse or mislead you. If you don’t need all the 4 periods then you can skip any period by pressing the hold button for 4 seconds and the set up moves to another period. Whereas, the great thing about other programmable thermostats is their sophistication of programming, the great thing about the Honeywell RTH221B is its lack of sophistication, its simplicity.

One of the few functions the Honeywell RTH221B does have is temporary hold. This is simplicity itself. If you are a bit cold you press the up button once to see the set point, press it again to raise the temperature 1 degree and again to raise it 2 degrees and so on. The thermostat then runs the HVAC at this higher temperature until the start of a new programmed period (such as the night period) when the original settings are returned to.

If you go away for a few days you simply set a temperature press hold and the thermostat maintains the house at that temperature until you return home and press ‘hold’ again to return back to your programmed settings.

Other than ‘hold’ the only other ‘function’ worthy of the name is the Honeywell RTH221B’s ability to keep its programmed settings even after a power outage.


As mentioned in the above review it is a matter of point of view whether you see the lack of programming options and functions as a drawback or an advantage. Some  people want as much control as possible over their heating and cooling; other people just want a basic programmable thermostat that you can use to set up a few programs and that you can quickly put on hold if you are a bit hot or cold. For this later group the Honeywell RTH221B Basic Programmable Thermostat is perfect.

And at only $20 simplicity does seem more attractive.

One drawback is that the thermostat is limited to just single stage heating and cooling and cannot manage heat pumps of any description. Also the lack of a back light might be irksome to people who want to check the thermostat at night.

Amazon Reviews

The Amazon reviews for the Honeywell RTH221B make for very interesting reading. It is possible to discount the odd criticism as down to a faulty device, but if the same criticism keeps reoccurring then it deserves to be taken more seriously. More than 5 reviewers out of a total of 64 reviews mentioned that the Honeywell RTH221B was not accurate. All these negative reviews  mentioned that the thermostat was about 5 degrees out. For some this was a minor problem that was easy to compensate for by altering the settings, for others it was symptomatic of bad and flawed equipment.

Furthermore, a couple of people noted that the Honeywell RTH221B stopped working altogether after 12 months.

At the same time many people commented about how they love the ease of programming, how the vertical design suits their house, how the device was easy to install and how the device works much better than their previous non-programmable thermostat.

I guess if you buy a Honeywell RTH221B bearing in mind that it is both ‘basic’ and ‘$20’ then you won’t have unreasonably high expectations for the device. It will definitely save you money (and pay for itself), but it is debatable whether it will be as accurate as more expensive Honeywell’s such as the RTH7500D, RTH7600D or the RTH8500D.

Keynote Quote:

“Seems to be perfect for the job, but it reads about 5 degrees F too high. Works well by setting up the control point.”

C. Brock

Thu, February 3 2011 » Honeywell, Under $30

Leave a Reply