Identify System Type

This thermostat is compatible with the following systems:

  •  Gas, oil, or electric furnace
  • Central air conditioner
  • Hot water system with or without pump
  • Millivolt system
  • Central heating and cooling system
  •  Heat pump without auxiliary/backup heat

Do you need assistance? We are here to help.

Honeywell RTH221B1047 Programmable Thermostat -- Call

Call 1-800-468-1502 for wiring assistance before returning the thermostat to the store.
This thermostat cannot be used on heat pumps with backup heat or on multistage systems.
Input: 2 x AAA batteries (1.5V each)

Honeywell RTH221B1047 Programmable Thermostat -- NOTICE

ATTENTION: MERCURY RECYCLING
NOTICE
This product does not contain mercury. However, this product may replace a product that contains mercury. Mercury and products containing mercury should not be discarded in household trash.
For more information on how and where to properly recycle a thermostat containing mercury in the United States, please refer to the Thermostat Recycling Corporation at www.thermostat-recycle.org.
For mercury thermostat recycling in Canada, please refer to Switch the Stat at www.switchthestat.ca

Honeywell RTH221B1047 Programmable Thermostat -- MERCURY

 NOTICE: To avoid possible compressor damage, do not run air conditioner if the outside temperature drops below 50°F (10°C).

Customer assistance
For assistance with this product, please visit resideo.com.
Or call Resideo Customer Care toll-free at 1-800-468-1502.
To save time, please note your model number and date code before calling.
Pull at the bottom to remove the thermostat from the wallplate.
Turn the thermostat over to find the model number and date code.

Honeywell RTH221B1047 Programmable Thermostat -- code
  1. Turn Off Power to Heating/Cooling System
  2. Remove Old Thermostat
    Remove old thermostat but leave wallplate with wires attached.
    If you have an older thermostat with a sealed mercury tube, turn to page 2 for proper disposal instructions.
  3.  Label Wires with Tags
    Label the wires using the supplied wire labels as you disconnect them.
    Honeywell RTH221B1047 Programmable Thermostat -- Label
  4. Separate Wallplate from New Thermostat
    Remove the wallplate from the new thermostat and mount it onto the wall.
    Honeywell RTH221B1047 Programmable Thermostat -- Wallplate
  5. Mount Wallplate
    Mount the new wallplate using the included screws and anchors.
    Honeywell RTH221B1047 Programmable Thermostat -- MountIf your box contains red anchors, drill 7/32” (5.6 mm) holes. If your box contains yellow anchors, drill 3/16” (4.8 mm) holes.
  6. Connect Wires
    Simply match wire labels.
    If labels do not match letters on the thermostat, check “Alternate Wiring” on page 6 and connect to the terminal as shown (see notes, below).
    The thermostat does not work on Heat Pumps with auxiliary/backup heat.
    Honeywell RTH221B1047 Programmable Thermostat -- WiresWe are here to help. Call 1-800-468-1502 for wiring assistance.
    Alternate Wiring
    Honeywell RTH221B1047 Programmable Thermostat -- Alternate• If wires will be connected to both R and Rc terminals, remove the metal jumper.
    • Do not use C or X. Wrap bare end of the wire with electrical tape.
    • If you have a heat pump without auxiliary/backup heat connect O or B, not both. If you do not have a heat pump, do not connect B. Wrap bare
    end of wire with electrical tape.
    • Place a jumper (a piece of wire) between Y and W if you are using a heat pump without auxiliary/backup heat.
  7. Install Batteries
    Install two AAA alkaline batteries.
    Honeywell RTH221B1047 Programmable Thermostat -- Batteries
  8. Set fan operation switch
    Honeywell RTH221B1047 Programmable Thermostat -- switchMove the switch to the proper setting:
    Gas or Oil: For gas or oil heating systems, leave the fan operation switch in this factory-set position (for systems that control the fan in a call for heat).
    Electric or Heat Pump: Change the switch to this setting for heat pump or electric heat systems. (This setting is for systems that allow the thermostat to control the fan in a call for heat, if a fan wire is connected to the terminal.)
  9. Install Thermostat onto Wallplate
    Honeywell RTH221B1047 Programmable Thermostat -- Thermostat.Install thermostat onto the wall plate on the wall.
  10. Turn Power Back On
    Turn the power back on to the heating/cooling system.
    Honeywell RTH221B1047 Programmable Thermostat -- Power Back
  11. If your system type is
    If your system type is:
    • Single-Stage Heat and Cool
    • Heat Only or Cool Only

Congratulations, you’re done!
If your system type is:
• Heat pump
• High-efficiency furnace
• Hot water
• Electric furnace
• Gas/oil steam
• Gravity system
Continue with Advanced Installation to match your thermostat to your system type.

If you are not sure of your system type or if you have other questions, call us toll-free at 1-800-468-1502.

This thermostat works on 24 volt or 750 mV systems. It will NOT work on multistage conventional systems.

Advanced Installation

Honeywell RTH221B1047 Programmable Thermostat -- Installation

Enter System Setup
To enter the system setup, press and hold both the Honeywell RTH221B1047 Programmable Thermostat -- button2and Honeywell RTH221B1047 Programmable Thermostat -- button1buttons until the display changes (approximately 5 seconds).

Honeywell RTH221B1047 Programmable Thermostat -- Settings

Changing Settings

  1. Press theHoneywell RTH221B1047 Programmable Thermostat -- button2 or Honeywell RTH221B1047 Programmable Thermostat -- button1button to change the setting.
  2. Press theHoneywell RTH221B1047 Programmable Thermostat -- button2 andHoneywell RTH221B1047 Programmable Thermostat -- button1buttons simultaneously for one second to advance to the next function.
  3. Press the RUN button to exit and save settings.

NOTE: If you do not press any button for 60 seconds while you are in the setup menu, the thermostat automatically saves any changes made and exits the menu.

FunctionDescription Press the or button toSetting
5select your heating system and optimize its operationGas or oil furnace: Use this setting if you have a standard gas or oil furnace that is less than 90% efficient.
6 Electric furnace: Use this setting if you have any type of electric heating system.
3 Heat pumps, hot water or high-efficiency furnace:
Use this setting if you have a hot water system or a gas furnace of greater than 90% efficiency.
2 Gas/oil steam or gravity system: Use this setting if you have a steam or gravity heat system.
14select Fahrenheit or Celsius temperature display0 Fahrenheit temperature display (°F)
1 Celsius temperature display (°C)
15*select Compressor Protection settings1 On0 Off
20select clock display0 12-hour display1 24-hour display
40 (RTH2300 only)restore program schedule to default settings0 Off1 On Program schedule default settings is listed on page 11.

* Compressor Protection: This feature forces the compressor to wait approximately 5 minutes before restarting, to prevent equipment damage. During the wait time, the message “Cool On” or “Heat On” is displayed on the screen.

About your new thermostat

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

  • Backlit display on RTH2300
  • Displays ambient (measured) temperature at all times
  • One-touch access to the setpoint temperature
  • Preset program settings
  • Temporary and permanent override of schedule
  • Built-in compressor protection

Thermostat controls

Honeywell RTH221B1047 Programmable Thermostat -- Thermostat controls

Display screen

Honeywell RTH221B1047 Programmable Thermostat -- Display screen

Set the time and day

  1. Press the SET button, then press Honeywell RTH221B1047 Programmable Thermostat -- button2or Honeywell RTH221B1047 Programmable Thermostat -- button1to set the clock time.
  2. Press the SET button, then press Honeywell RTH221B1047 Programmable Thermostat -- button2or Honeywell RTH221B1047 Programmable Thermostat -- button1to select the day of the week.
  3. Press RUN to save & exit.

NOTE: If the clock flashes, the thermostat will follow your settings for the Monday “Wake” time period until you reset the time and day.

Honeywell RTH221B1047 Programmable Thermostat -- time
Honeywell RTH221B1047 Programmable Thermostat -- Schedule

Program Schedule
You can program four time periods each day, with different settings for weekdays and weekends. We recommend the pre-set settings (shown in the table below), since they can reduce your heating/cooling expenses.

Wake – Set to the time you awaken and the temperature you want during the morning, until you leave for the day.
Leave – Set to the time you leave home and the temperature you want while you are away (usually an energy-saving level).
Return – Set to the time you return home and the temperature you want during the evening, until bedtime.
Sleep – Set to the time you go to bed and the temperature you want overnight (usually an energy-saving level).
NOTE: Leave and Return periods can be canceled on weekends.

Honeywell RTH221B1047 Programmable Thermostat -- schedules

To adjust program schedules (RTH2300)

  1. Press SET until Set Schedule is displayed.
  2. Press or Honeywell RTH221B1047 Programmable Thermostat -- button1to set your weekday Waketime (Mo-Fr), then press SET.
  3. Press Honeywell RTH221B1047 Programmable Thermostat -- button2or Honeywell RTH221B1047 Programmable Thermostat -- button1to set the temperature for this time period, then press SET.
  4. Set time and temperature for the next time period (Leave). Repeat steps 2 and 3 for each weekday time period.
  5. Press SET to set weekend time periods (Sa & Su), then press RUN to save & exit.

NOTE: Make sure the thermostat is set to the system you want to program (Heat or Cool).

To adjust program schedules (RTH221)

Honeywell RTH221B1047 Programmable Thermostat -- RTH221
  1. Press SET until Set Schedule is displayed.
  2. Press orHoneywell RTH221B1047 Programmable Thermostat -- button1to set your Waketime (Mo-Su), then press SET.
  3. Press orHoneywell RTH221B1047 Programmable Thermostat -- button1 to set the temperature for this time period, then press SET.
  4. Set time and temperature for the next time period (Leave). Repeat steps 2 and 3 for each time period.
  5. Press RUN to save & exit.

NOTE: Make sure the thermostat is set to the system you want to program (Heat or Cool).

Program schedule override (temporary)

Press orHoneywell RTH221B1047 Programmable Thermostat -- button1to immediately adjust the temperature. This will temporarily override the temperature setting for the current time period.

Honeywell RTH221B1047 Programmable Thermostat -- Program


“Temporary” will appear on the display and the current program period will flash.
The new temperature will be maintained only until the next programmed time period begins (see page 11).
To cancel the temporary setting at any time, press RUN.
NOTE: Make sure the thermostat is set to the system you want to control (heat or cool).

Program schedule override (permanent)

Press HOLD to permanently adjust the temperature. This will override the temperature settings for all time periods.

Honeywell RTH221B1047 Programmable Thermostat -- permanent


The “Hold” feature turns off the program schedule and allows you to adjust the thermostat manually, as needed.
Whatever temperature you set will be maintained 24 hours a day, until you manually change it, or press RUN to cancel “Hold” and resume the program schedule.
NOTE: Make sure the thermostat is set to the system you want to control (heat or cool).

Built-in compressor protection

Honeywell RTH221B1047 Programmable Thermostat -- compressor

This feature helps prevent damage to the compressor in your air conditioning or heat pump system.
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 display will flash the message Cool On (or Heat On if you have a heat pump). When the safe wait time has elapsed, the message stops flashing and the compressor turns on.

Battery replacement

Install two fresh AAA batteries when Lo Batt flashes on the screen. Lo Batt appears for 60 days before the batteries are depleted.

Honeywell RTH221B1047 Programmable Thermostat -- Battery11
Honeywell RTH221B1047 Programmable Thermostat -- Battery22


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 and the day must be set after you replace the batteries.
Honeywell RTH221B1047 Programmable Thermostat -- NOTICESet the System switch to Off before removing the batteries. Otherwise, the heating/cooling system could remain activated even when batteries are removed.

Troubleshooting

If you have difficulty with your thermostat, please try the following suggestions.
Most problems can be corrected quickly and easily.

Display is blank• Check the circuit breaker and reset if necessary.
• Make sure the power switch at the heating & cooling system is on.
• Make sure the furnace door is closed securely.
• Make sure fresh AAA alkaline batteries are correctly installed.
The heating or cooling system does
not respond
• Set system switch to Heat. Make sure the temperature is set higher than the Inside temperature.
• Set system switch to Cool. Make sure the temperature is set lower than the Inside temperature.
• Wait 5 minutes for the system to respond.
Temperature settings do
not change
Make sure heating and cooling temperatures are set to acceptable ranges:
• Heat: 40° to 90°F (4.5° to 32°C).
• Cool: 50° to 99°F (10° to 37°C).
“Cool On” or “Heat On” is
flashing
• Compressor protection feature is engaged. Wait 5 minutes for the system to restart safely, without damage to the compressor.
Heat On” is not displayed• Set the System switch to Heat and set the temperature level above the current room temperature.
“Cool On” is not displayed• Set the System switch to Cool, and set the temperature level below the current room temperature.

For assistance with this product, please visit resideo.com or call Resideo Customer Care toll-free at 1-800-468-1502.

1-year limited 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 that 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 RESIDE 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.

www.resideo.com
Resideo Technologies Inc.
1985 Douglas Drive North, Golden Valley, MN 55422
1-800-468-1502
33-00100EF—03 M.S. Rev. 02-20 | Printed in the 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.

Documents / Resources

Honeywell RTH221B1047 Programmable Thermostat [pdf] Owner’s Manual
RTH221B1047, RTH2300B1020, Programmable Thermostat

References

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