Honeywell Home RTH221 User Manual (English)

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USER GUIDE

69-2062EFS-03

RTH221 Programmable

Thermostat

1. OPERATION

1.1 Controls

1.2 Display Screen

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

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Honeywell Home RTH221 Specifications

Power

power supply	2 AAA batteries
maximum load	1 A at 24 V AC per output

Operating Environment

operating temperature range for heating	4.5 °C to 32 °C (40 °F to 90 °F)
operating temperature range for cooling	10 °C to 37 °C (50 °F to 99 °F)
operating ambient temperature	0 °C to 50 °C (32 °F to 122 °F)
shipping temperature	-40 °C to 55 °C (-40 °F to 130 °F)
operating relative humidity	5% to 90% (non-condensing)

Weight and Dimensions