Honeywell RTH221 Programmable Thermostat User Guide

1.1 Controls

The thermostat features several controls:

• Clock/Schedule Setting: Press the 'Set' button to adjust the clock and schedule.
• Override/Hold: Press the [up arrow] or [down arrow] buttons to temporarily or permanently override the programmed schedule and set a desired temperature.
• Run Schedule: Press the 'Run' button to activate the programmed schedule.

Switches and Indicators:

• Fan Switch: Selects fan operation (Auto or On).
• System Switch: Selects system mode (Cool, Off, or Heat).
• Temperature Adjustment Buttons: Use [up arrow] / [down arrow] to adjust the setpoint temperature.

The display screen shows the current time, system status (e.g., 'Cool On', 'Heat On'), setpoint temperature, and warnings like low battery.

1.2 Display Screen

The display includes:

• Setpoint Indicator: Appears when the setpoint temperature is displayed.
• Low-battery warning: ? Indicates batteries need replacement.
• Schedule Period Indicator: Shows the current part of the programmed schedule (e.g., Wake, Leave).
• Clock Display: Shows the current time.
• Temporary Schedule Override: Indicates a temporary temperature setting is active.
• Temperature Display: Shows the current ambient temperature or the setpoint temperature.
• System Status: Displays 'Cool On' when cooling is active or 'Heat On' when heating is active.

Note: If 'Cool On' is flashing, the compressor protection feature is active, preventing immediate restart.

1.3 Setting the Clock

1. Press the 'Set' button. 'Set Time' appears, and the time display flashes.
2. Use the [up arrow] or [down arrow] buttons to set the correct time.
3. Press the 'Run' button to save changes and exit. Changes are also saved if no button is pressed for 60 seconds.

Note: If the time display flashes, the clock settings have been lost. The thermostat will use the programmed 'Wake' period settings until the clock is reset.

1.4 System Switch

Use the System switch to select one of the following modes:

• Cool: System operates in Cooling mode.
• Off: System is turned off.
• Heat: System operates in Heating mode.

Caution: Do not use Cooling mode when the outdoor temperature is below 50°F (10°C).

1.5 Fan Switch

Use the Fan switch to control the fan:

• Auto: The fan runs only when heating or cooling is active.
• On: The fan runs continuously.

1.6 Temperature Setting

Press the [up arrow] or [down arrow] button once to view the setpoint temperature. Press either button again to change the setpoint. The setpoint will be displayed for five seconds.

1.7 Built-in Compressor Protection

This feature prevents damage to the air conditioning compressor by ensuring a minimum 5-minute delay before restarting after a shutdown. During this delay, 'Cool On' will flash on the screen.

2.1 Using the Schedule

Press the 'Run' button to follow the programmed schedule. You can program up to four periods per day, each with a different temperature setting.

• Wake: Morning temperature
• Leave: Daytime temperature
• Return: Evening temperature
• Sleep: Night temperature

Each period requires a start time and two temperature settings (one for cooling, one for heating). The same schedule repeats daily.

Programming the schedule for economical temperatures when away or sleeping and comfortable temperatures when home can save energy while maintaining comfort.

2.2 Factory Settings

2.3 Modifying the Schedule

1. Press 'Set' twice until 'Set Schedule' appears. The Wake period start time will flash.
2. Use [up arrow]/[down arrow] to set the time.
3. Press 'Set'. The temperature setting for that period will flash.
4. Set the System switch to 'Cool' for cooling temperatures or 'Heat' for heating temperatures.
5. Use [up arrow]/[down arrow] to set the temperature.
6. Press 'Set'. The start time of the next period will flash.
7. Repeat steps 2-6 for remaining periods. You can skip a period (except Wake) by pressing and holding 'Hold' for 4 seconds. Dashes will appear for skipped periods.
8. Press 'Run' to save and exit.

2.4 Temporary Override of Schedule

To temporarily change the temperature, press [up arrow] or [down arrow] until the desired temperature is displayed. The word 'Temporary' will appear, and the current period will flash. The new temperature will be used until the next scheduled period begins. Press 'Run' to cancel the temporary setting before the next period.

2.5 Permanent Override of Schedule

To permanently hold a temperature, press [up arrow] or [down arrow] until the desired temperature is displayed. Then, press the 'Hold' button. The word 'Hold' will appear, and the thermostat will maintain this temperature indefinitely. Press 'Run' to cancel the override and return to the programmed schedule.