Pentax RTH221 Operation Manual

RTH221

1-day Programmable Thermostat

Operating
Manual

69-2388ES-03

CAUTION: EQUIPMENT DAMAGE HAZARD

To prevent possible compressor damage, do not use Cooling mode when the
outdoor temperature is below 50°F (10°C).

Need Help?

For assistance with this product please visit http://DIYthermostats.honeywell.com

or call Honeywell Customer Care toll-free at 1-800-468-1502.

Read and save these instructions.

Table of contents

Overview

Thermostat features ..............................2

Quick start .............................................3

Quick reference to controls ...................4

Quick reference to display.....................5

Programming & Operation

Setting the clock....................................6

System switch (Heat/Cool)....................7

Fan switch (Auto/On).............................8

Using the schedule...........................9-11

Temporary schedule override..............12

Permanent schedule override .............13

Compressor protection........................14

Programmable Thermostat RTH221

Appendices

Battery replacement ........................... 15

In case of difficulty .............................. 16

Customer assistance .......................... 17

One-year limited warranty ..................18

Your new thermostat is pre-programmed

and ready to go!

See page 3 for quick start.

Operating Manual

About your new thermostat

Your new thermostat has been designed to give you many years of reliable service and
easy-to-use, push-button climate control.

Features

• Displays ambient (measured) temperature at all times

• One-touch access to setpoint temperature

• Daily heating/cooling schedule to greatly reduce your heating/cooling expenses

• Temporary and permanent override of schedule

• Built-in compressor protection

2

Programmable Thermostat RTH221

This thermostat is ready to go

Simply perform the three steps below and the thermostat is in operation:

1 Set the clock ................................................................................................ See page 6

2 Select whether to heat or cool...................................................................... See page 7

3 Select whether to run the fan continuously or only when needed................ See page 8

Your thermostat is pre-programmed with a daily heating/cooling schedule. If you do not
wish to use these settings, you can:

 Modify the schedule ....................................................................................See page 11

 Temporarily override the schedule ............................................................. See page 12

 Permanently override the schedule............................................................ See page 13

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Operating Manual

System switch (see page 7)

• Cool: System is in Cooling mode.

• Off: System is off.

• Heat: System is in Heating mode.

Fan switch (see page 8)

• On: Fan runs continuously.

• Auto: Fan runs only when
heating or cooling is activated.

Up/Down buttons
Press to adjust temperature.

Press to set clock, day or
schedule (see pages 6 & 11).

Press to override schedule and
hold temperature (see page 13).

Press to run (follow) schedule
(see page 9).

Quick reference to controls

4

Quick reference to display

* When Heat On or Cool On is flashing, compressor protection is engaged (see page 14).

Temperature

The ambient (measured) temperature is
normally displayed. To view the setpoint
temperature, press the Up or Down
button once. The setpoint temperature
will appear for five seconds.

System status

• Cool On: Cooling is activated. *

• Heat On: Heating is activated. *

Low-battery warning
(see page 15)

Setpoint indicator

Appears when the setpoint
temperature is displayed.

Clock

Schedule period

Permanent schedule override

(see page 13)

Temporary schedule override

(see page 12)

Programmable Thermostat RTH221

5

Operating Manual

Set the clock

1 Press the Set button. Set Time will appear on the screen and the

time display will flash.
2 Press the Up or Down button to set the time.
3 Press the Run button to save the changes & 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 display flashes. If the thermostat is
following the schedule, it will use the temperature settings programmed for the Wake
period until you readjust the clock.

6

System switch (Heat/Cool)

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).

Programmable Thermostat RTH221

7

Operating Manual

Use the Fan switch to select the fan operation.

• Auto: The fan runs only when heating or
cooling is activated (commonly used setting).

• On: The fan runs continuously.

Fan switch (Auto/On)

8

Programmable Thermostat RTH221

Using the schedule

Press the Run button to follow the programmed schedule. For maximum energy savings
while maintaining comfort, you can program the schedule such that the temperature is at
an economical level when you sleep or leave for work and at a comfortable level when you
are awake and at home. You can program up to four periods per day:

Wake Starts when you wake up
Leave Starts when you leave for work
Return Starts when you return home
Sleep Starts when you go to sleep

To program a period, you need to set its start time and its two temperature settings (one
when the thermostat is in cooling mode and another one when it is in heating mode). The
same settings are used every day.

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Operating Manual

Energy saving settings

The thermostat has been programmed with the following heating/cooling schedule. See the
next page if you wish to modify the settings.

Period Start time Heat Cool

Wake 6:00 AM 70°F (21°C) 78°F (25.5°C)

Leave 8:00 AM 62°F (16.5°C) 85°F (29.5°C)

Return 6:00 PM 70°F (21°C) 78°F (25.5°C)

Sleep 10:00 PM 62°F (16.5°C) 82°F (27.5°C)

10

Programmable Thermostat RTH221

Wake period is set
to 6 a.m. and 70°F

To skip a period
(except Wake),
press the Hold
button for 4 seconds
while that period is
displayed.

Modifying the schedule

1Press the Set button 2 times until Set Schedule appears. The Wake period is

displayed.

NOTE: To set another period, press the Set button as many times as needed until the
desired period is displayed and its time or temperature is flashing.

2 When the time flashes, press the Up or Down button to set the time.
3Press the Set button.

4 To set the temperature for cooling mode, first place the System switch in Cool. To

set the temperature for heating mode, first place the System switch in Heat.
5 When the temperature flashes, press the Up or Down button to set the temperature.
6Press the Set button.
7 Repeat steps 2 through 6 to set each of the remaining periods.
8 Once all changes are made, press the Run button to save them and return to

normal display. (The changes will automatically be saved if you do not press any

button for 60 seconds.)

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Operating Manual

Temporary override of schedule

To temporarily ignore the schedule, press the Up or
Down button until the desired temperature is displayed.

The word Tempo rary will appear on the screen and the
period display will flash to indicate that the current period
has been overridden. The new temperature will be used
until the next period begins.

NOTE: Pressing the Up or Down button once will display the setpoint temperature. To
change the setpoint temperature, press either button more than once.

Press the Run button if you wish to cancel the temporary setting before the beginning of
the next period.

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