Honeywell RTH221 Series User manual

69-2388ES-03
RTH221
1-day Programmable Thermostat
Operating
Manual

Read and save these instructions.
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.

Programmable Thermostat RTH221
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
Appendices
Battery replacement ........................... 15
In case of difficulty .............................. 16
Customer assistance .......................... 17
One-year limited warranty .................. 18
Table of contents
Your new thermostat is pre-programmed
and ready to go!
See page 3 for quick start.

Operating Manual
2
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
About your new thermostat

Programmable Thermostat RTH221
3
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
This thermostat is ready to go

Operating Manual
4
Quick reference to controls
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).

Programmable Thermostat RTH221
5
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)

Operating Manual
6
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.
Set the clock

Programmable Thermostat RTH221
7
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).

Operating Manual
8
Fan switch (Auto/On)
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.

Programmable Thermostat RTH221
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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:
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.
Using the schedule
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

Operating Manual
10
The thermostat has been programmed with the following heating/cooling schedule. See the
next page if you wish to modify the settings.
Energy saving 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)

Programmable Thermostat RTH221
11
1PresstheSet 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.
3PresstheSet 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.
6PresstheSet 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.)
Modifying the schedule
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.

Operating Manual
12
To temporarily ignore the schedule, press the Up or
Down button until the desired temperature is displayed.
The word Temporary 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.
Temporary override of schedule

Programmable Thermostat RTH221
13
To permanently ignore the schedule, press the Up or
Down button until the desired temperature is displayed.
Then, press the Hold button to maintain the new
temperature indefinitely. The word Hold will appear on
the screen.
Press the Run button if you wish to cancel the override
and resume the schedule. The word Hold will disappear
and the thermostat will be set to the temperature
programmed for the current period.
Permanent override of schedule

Operating Manual
14
Your thermostat has a feature that helps prevent damage to the compressor of your air
conditioning or heat pump system. Because damage can occur if the compressor is
restarted too soon after shutdown, this feature forces the compressor to wait 5 minutes
before restarting. During the wait time, the message Cool On or Heat On flashes on the
screen. When the safe wait time has elapsed, the message stops flashing and the
compressor turns on.
Built-in compressor protection

Programmable Thermostat RTH221
15
Install two fresh AAA batteries when Lo Batt flashes on
the screen. Lo Batt appears for 60 days before the
batteries are depleted.
Replace batteries once a year, or when you will be away
for more than a month.
Most settings are stored in non-volatile (permanent)
memory. Only the clock must be set after you replace the
batteries.
Battery replacement
Set the System switch to Off before removing the batteries. Otherwise, the
heating/cooling system could remain activated even when batteries are
removed.

Operating Manual
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In case of difficulty
Screen is blank. • Ensure two fresh AAA alkaline batteries are correctly installed.
Temperature settings cannot be
changed.
• The System switch is off.
• You are setting the temperature outside its allowable range:
• Heat: 40°F to 90°F (4.5°C to 32°C)
• Cool: 50°F to 99°F (10°C to 37°C)
Cool On or Heat On is flashing. • The compressor protection delay is underway. Wait for the delay
to end (maximum of 5 minutes).
HI appears on the screen. • The ambient (measured) temperature is above 122°F (50°C).
LO appears on the screen. • The ambient (measured) temperature is below 32°F (0°C).
E1 appears on the screen. • The temperature sensor circuit is opened. Replace the thermostat.
E2 appears on the screen. • The temperature sensor circuit is shorted. Replace the thermostat.

Programmable Thermostat RTH221
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For assistance with this product, please visit http://DIYthermostats.honeywell.com.
Or call Honeywell Customer Care toll-free at 1-800-468-1502.
To save time, before calling, proceed as follows:
1) Loosen the locking screw at the bottom of the thermostat. Note that
the screw is captive and cannot be removed from the wallplate.
2) Separate the thermostat from the wallplate as per figure on the right.
3) Note your model number and date code on the thermostat’s
wallplate.
Customer assistance

Operating Manual
18
Honeywell warrants this product, excluding battery, to be free from defects in the workmanship or
materials, under normal use and service, for a period of one (1) year from the date of purchase by the
consumer. If at any time during the warranty period the product is determined to be defective or
malfunctions, Honeywell shall repair or replace it (at Honeywell’s option).
If the product is defective,
(i) return it, with a bill of sale or other dated proof of purchase, to the place from which you purchased
it; or
(ii) call Honeywell Customer Care at 1-800-468-1502. Customer Care will make the determination
whether the product should be returned to the following address: Honeywell Return Goods, Dock 4
MN10-3860, 1885 Douglas Dr. N., Golden Valley, MN 55422, or whether a replacement product
can be sent to you.
This warranty does not cover removal or reinstallation costs. This warranty shall not apply if it is shown
by Honeywell that the defect or malfunction was caused by damage which occurred while the product
was in the possession of a consumer.
One-year limited warranty