How to Program an RTH221B Honeywell Thermostat

The Honeywell RTH221B thermostat is a one-week programmable thermostat. Once you set the program for the heating or cooling season, you never need to adjust the thermostat unless you modify your personal schedule. Programming an RTH221B Honeywell thermostat is straightforward because there are only four program schedules. You can set a different temperature for when you wake up, leave the house, arrive home and finally when you go to bed.

Step 1

Go to the Honeywell RTH221B thermostat and locate the "Set" button. There are three buttons on the upper left-hand side of the thermostat. The first button is the "Set" button. Turn the mode switch on the right side of the thermostat to either "Cool" or "Heat" depending upon the season.

Step 2

Press and release the "Set" button twice to place the thermostat in programming mode. Pressing the button once places the clock in programming mode only. When you press the button twice, the time of the "Wake" setting flashes on the display screen.

Step 3

Hold one of the directional buttons below the screen to adjust the wake time up or down. Release the directional button once you reach the time you want the "Wake" setting to begin. Press and release the "Set" button again to bring up the next programming period.

Step 4

Continue setting the remaining three programming periods in exactly the same manner. Press and release the "Run" button once you program the settings.