Honeywell RTH221 Programmable Thermostat User Guide

: June 6, 2024
: Honeywell

Honeywell RTH221 Programmable Thermostat User Guide

1. OPERATION

1.1 Controls

Honeywell RTH221 Programmable Thermostat User Guide -
Controls

1.2 Display Screen

Honeywell RTH221 Programmable Thermostat User Guide - Display
Screen

¹ When Cool On is flashing, this means the compressor protection is engaged (see section 1.7).

1.3 Setting the Clock

Press the Set button. The message Set Time will appear on the screen and the time display will flash.
Press the ▲or ▼ button to set the time.
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 display 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.

Honeywell RTH221 Programmable Thermostat User Guide - Bar
Code

Honeywell RTH221 Programmable Thermostat User Guide -
Wake

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 period and settings are repeated every day.

For maximum energy savings without sacrificing comfort, you can program the schedule such that the temperature is at an economical level when you sleep or are away during the day and at a comfortable level when you are awake and at home.

2.2 Factory settings

Honeywell RTH221 Programmable Thermostat User Guide - Factory
settings

2.3 Modifying the schedule

Honeywell RTH221 Programmable Thermostat User Guide - Modifying the
schedule

Press the Set button twice until the message Set Schedule appears. The start time of the first period (Wake) will flash.
Press the▲ or ▼ button to set the time.
Press the Set button. The temperature setting for that period will flash.
To program the temperature settings for the cooling mode, place the System switch in Cool. To program the temperature settings for the heating mode, place the switch in Heat.
Press the ▲or ▼ button to set the temperature.
Press the Set button. The start time of the next period will flash.
NOTE:
To skip a period, press the Hold button for four seconds while that period is displayed. When a period is skipped, dashes appear instead of the time and temperature display for the period. Only the Wake period cannot be skipped.
Repeat steps 2 through 6 for each of the remaining periods.
Once all adjustments are made, press the Run button to save them and exit. (The changes are also saved if you do not press any button for 60 seconds.)

2.4 Temporary override of schedule

To temporarily ignore the programmed schedule, press ▲ or ▼ 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 ▲ or ▼ 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.

2.5 Permanent override of schedule

To permanently ignore the programmed schedule, press ▲ or ▼ 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 programmed schedule. The word Hold will disappear and the thermostat will be set to the temperature programmed for the current period.

3. 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.

Install two fresh AAA batteries when Lo Batt (low batteries) flashes on the screen. The icon 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 if the thermostat was without batteries.

4. 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 temperatures outside their allowable ranges:
— 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 is flashing.
The compressor protection delay has been activated. Cooling will not be activated until the delay ends (maximum of five 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.

5. TECHNICAL DATA

Power Supply
2 AAA batteries

Maximum Load
1 A @ 24 VAC per output

Temperature Ranges
Heat: 40 °F to 90 °F (4.5 °C to 32 °C)
Cool: 50 °F to 99 °F (10 °C to 37 °C)

Operating Ambient Temperature
32 °F to 122 °F (0 °C to 50 °C)

Shipping Temperature
-40 °F to 130 °F (-40 °C to 55 °C)

Operating Relative Humidity
5% to 90% (non-condensing)

Physical Dimensions (H x W x D)
4.7” x 2.9” x 1.1” (120 mm x 74 mm x 28 mm)

WARRANTY
Resideo warrants this product, excluding battery, to be free from defects in workmanship or materials, under normal use and service, for a period of one (1) year from the date of first purchase by the original purchaser. If at any time during the warranty period the product is determined to be defective due to workmanship or materials, Resideo shall repair or replace it (at Resideo’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 Resideo Customer Care at 1-800-468-1502. Customer Care will make the determination whether the product should be returned to the following address:

Resideo Return Goods, 1985 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 Resideo that the defect was caused by damage which occurred while the product was in the possession of a consumer.

Resideo’s sole responsibility shall be to repair or replace the product within the terms stated above. RESIDEO SHALL NOT BE LIABLE FOR ANY LOSS OR DAMAGE OF ANY KIND, INCLUDING ANY INCIDENTAL OR CONSEQUENTIAL DAMAGES RESULTING, DIRECTLY OR INDIRECTLY, FROM ANY BREACH OF ANY WARRANTY, EXPRESS OR IMPLIED, OR ANY OTHER FAILURE OF THIS PRODUCT.

Some states do not allow the exclusion or limitation of incidental or consequential damages, so this limitation may not apply to you.

THIS WARRANTY IS THE ONLY EXPRESS WARRANTY RESIDEO MAKES ON THIS PRODUCT. THE DURATION OF ANY IMPLIED WARRANTIES, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, IS HEREBY LIMITED TO THE ONE YEAR DURATION OF THIS WARRANTY. Some states do not allow limitations on how long an implied warranty lasts, so the above limitation may not apply to you.

This warranty gives you specific legal rights, and you may have other rights which vary from state to state. If you have any questions concerning this warranty, please write Resideo Customer Care, 1985 Douglas Dr, Golden Valley, MN 55422 or call 1-800-468-1502.

CUSTOMER ASSISTANCE
If you have any questions regarding your thermostat, please go to http://honeywellhome.com or call Customer Care toll-free at 1-800-468-1502.

www.resideo.com

Resideo Technologies, Inc. 1985 Douglas Drive North, Golden Valley, MN 55422 1-800-468-1502 69-2062EFS–03 M.S. Rev. 09-21 | Printed in United States

© 2020 Resideo Technologies, Inc. All rights reserved. The Honeywell Home trademark is used under license from Honeywell International, Inc. This product is manufactured by Resideo Technologies, Inc. and its affiliates.