USER GUIDE
69-2062EFS-03
RTH221 Programmable
Thermostat
1. OPERATION
1.1 Controls
1.2 Display Screen
1
When
Cool On
is flashing, this means the compressor
protection is engaged (see section 1.7).
1.3 Setting the Clock
1.
Press the
Set
button. The message
Set
Time
will appear on the screen and the
time display will flash.
2.
Press the
or
button to set the time.
3.
Press the
Run
button to save the changes
and exit. (The changes are also saved if you
do not press any button for 60 seconds.)
NOTE:
The clock has lost its settings when the time dis-
play flashes. If the thermostat is following the
programmed schedule, it will use the temperature
settings programmed for the
Wake
period until
you readjust the clock.
1.4 System switch
Use the
System
switch to place the system in one of the
following modes.
•
Cool:
System is in Cooling mode.
•
Off:
System is off.
•
Heat:
System is in Heating mode.
CAUTION
EQUIPMENT DAMAGE HAZARD
Do not use Cooling mode when the outdoor
temperature is below 50 °F (10 °C).
1.5 Fan switch
Use the
Fan
switch to select the fan operation.
•
Auto:
The fan runs only when heating or cooling is
actually taking place (commonly used setting).
•
On:
The fan runs continuously.
1.6 Temperature setting
Press the
or
button once to display the setpoint
temperature. Press either button more than once to
change the setpoint.
The ambient (measured) temperature is normally
displayed. To view the setpoint temperature, press either
of the temperature adjustment buttons once. The setpoint
temperature will appear for five seconds.
1.7 Built-in compressor protection
Your thermostat has a feature that helps prevent damage
to the compressor of your air conditioning system.
Because damage can occur if the compressor is restarted
too soon after shutdown, this feature forces the
compressor to wait five minutes before restarting. During
the wait time, the message
Cool On
flashes on the screen.
When the safe wait time has elapsed, the message stops
flashing and the compressor turns on.
2. PROGRAMMED SCHEDULE
2.1 Using the schedule
Press the Run button to follow the programmed schedule.
You can have up to four periods in one day. Each period
can be programmed with a different temperature setting.
Fan switch
System switch
Temperature
adjustment buttons
Press to run (follow)
programmed schedule
Press to override
schedule and hold
temperature
Press to set clock
or schedule
Low-battery warning
Permanent
schedule override
Schedule period
Low-battery warning
Setpoint Indicator
Appears when the setpoint
temperature is displayed
Temperature
Clock
Temporary
Schedule Override
System status
Cool On:
Cooling is
activated¹
Heat On:
Heating is
activated
