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OPERATING INSTRUCTIONS The RTH5100B Thermostat provides electronic control of 24 Vac single stage heating and cooling systems or 750 mV heating systems. For assistance with your Honeywell product please visit www.honeywell.com/yourhome or call Honeywell Customer Care toll free at 1-800-468-1502.
Features • Large, Clear, Backlit Display: Easy-to-see and read—even in the dark. • Precise Comfort Control: ±1ºF of your set temperature. • Simplified Operation: Soft-key controls. Simultaneously displays both room temperature and temperature setting. • Easy Change Battery Holder. • Built-in Compressor Protection: Minimum-off timer protects compressor from restarting too early after a shutdown.
Get To Know Your Thermostat Thermostat DIGITAL DISPLAY BATTERY HOLDER LATCH PRESS TO RELEASE BATTERY HOLDER. BATTERY HOLDER TWO AAA ALKALINE BATTERIES TEMPERATURE SETTING BUTTON RAISES TEMPERATURE SETTING TEMPERATURE SETTING BUTTON LOWERS FAN BUTTON TEMPERATURE SELECTS AUTO OR ON SETTING SYSTEM BUTTON SELECTS HEAT, OFF OR COOL M22010...
Get to Know Your Thermostat (Cont) Display INSIDE INDICATES BATTERIES ARE TEMPERATURE LOW AND MUST BE REPLACED Heat Cool Replace Batt Inside Setting TEMPERATURE SETTING Heat INDICATES Cool THERMOSTAT IS System "CALLING" FOR HEAT OR COOL On Auto Heat Cool CURRENT CURRENT SYSTEM SETTING...
Operate Your Thermostat Set System Setting Press the System button to select Heat, Off or Cool: Heat—Thermostat controls the heating system. Off—Both the heating and cooling systems are off. Cool—Thermostat controls the cooling system. CAUTION Equipment Damage Hazard. Air conditioning compressor damage possible. Do not operate cooling system when outdoor temperature is below 50 °F (10 °C).
Operate Your Thermostat (Cont) Set Fan Setting Press the Fan button to select Auto or On: Auto—Normal setting for most homes.The fan runs only when the heating or cooling system is on. On—The fan runs continuously. Use this setting for improved air circulation or for more efficient air cleaning.
Operate Your Thermostat (Cont) Change Temperature Setting Press the Up or Down button to select the desired temperature setting. TEMPERATURE SETTING PRESS THIS Replace Batt BUTTON TO RAISE THE TEMPERATURE SETTING Service Needed System Auto Cool PRESS THIS BUTTON TO LOWER THE TEMPERATURE SETTING TEMPERATURE SETTING RANGE:...
Replace Batteries 1. When the Replace Battery indicator is flashing, replace batteries promptly with two fresh AAA alkaline batteries. REPLACE BATTERY INDICATOR Replace Batt Service Needed System Cool Auto M22015 The thermostat does not lose any settings when the batteries are replaced; all settings are permanently stored in memory.
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Replace Batteries (Cont) 2. Press the battery holder latch to release the battery holder. 3. Remove the battery holder from the thermostat. BATTERY HOLDER BATTERY HOLDER LATCH Service Needed Auto Cool M22016 69-1722...
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Replace Batteries (Cont) 4. Remove the old batteries and insert two fresh AAA alkaline batteries as marked on the battery holder. BATTERY HOLDER PUSH BATTERIES THROUGH THIS HOLE BATTERY DIRECTION M22017 69-1722...
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Replace Batteries (Cont) 5. Insert battery holder as shown. BATTERY HOLDER BATTERY HOLDER LATCH Service Needed Auto Cool M22016 69-1722...
Review Battery Tips 1. Replace the batteries as soon as Replace Batt flashes in the display. The Replace Battery indicator flashes in the display two months before the batteries run down completely. 2. Always use fresh AAA alkaline batteries. Non-alkaline batteries do not last as long and can leak, causing thermostat damage.
Built-in Compressor Protection The RTH5100B Thermostat has built-in compressor protection (minimum-off timer) that prevents the compressor from restarting too early after a shutdown. The minimum-off timer is activated after the compressor turns off. If there is a call during the minimum-off timer, the thermostat flashes “Cool On”...
Accessory/Replacement Parts 1. Cover Plates—Used to cover marks on the wall Part Number: 50001137-001 (Small) Cover Plate 50002883-001 (Large) Cover Plate To order, call Honeywell Customer Care at 1-800-468-1502. M22185 2. Replacement Battery Holder— Part Number 50000951-001 Battery Holder To order, call Honeywell Customer Care at 1-800-468-1502.
Troubleshooting Tips If . . . Then . . . Display is Check that fresh AAA alkaline batteries blank. are installed as marked on the battery holder. Temperature Check that the temperature settings are: settings do • Heating 40°F to 90°F(4.5°C to 32°C). not change.
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Troubleshooting Tips (Cont) If . . . Then . . . Cooling • Set the system to Cool by pressing system does the System button. not turn on. • Check the cool temperature setting to be sure it is set below the room temperature and “Cool On”...
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Troubleshooting Tips (Cont) If . . . Then . . . “Heat On” is Set the System setting to Heat and set not shown in the temperature setting above the room the display. temperature. If “Heat On” is shown solidly in the display, but the heating system does not turn on, see “Heating system does not turn on”...
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Troubleshooting Tips (Cont) If . . . Then . . . Fan does not Check Installer Setup Number 3, Fan turn on in a Control in Heating, and make sure it is call for heat set to Electric Heat (Setting 1).Refer to (electric Installation Instructions, 69-1716 furnaces...
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Troubleshooting Tips (Cont) If . . . Then . . . Heating Check Installer Setup Number 1, Heating system is and/or Cooling System Type, and make running in sure the setting matches the installed cool mode. heating and/or cooling system. Refer to Installation Instructions, 69-1716.
Customer Assistance For assistance with your Honeywell product please visit www.honeywell.com/yourhome or call Honeywell Customer Care toll free at 1-800-468-1502. Before calling, please have the thermostat model number and date code available. MODEL NUMBER DATE CODE THERMOSTAT BATTERY HOLDER M22178 Limited One Year Warranty…...
Golden Valley, MN 55422 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.
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If you have any questions concerning this warranty, please write Honeywell Customer Relations, 1985 Douglas Dr, Golden Valley, MN 55422 or call 1-800-468-1502. In Canada, write Retail Products ON15-02H, Honeywell Limited/Honeywell Limitée, 35 Dynamic Drive, Scarborough, Ontario M1V4Z9.
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Automation and Control Solutions Honeywell International Inc. Honeywell Limited-Honeywell Limitée 1985 Douglas Drive North 35 Dynamic Drive Golden Valley, MN 55422 Scarborough, Ontario M1V 4Z9 69-1722 G.H. 5-04 www.honeywell.com/yourhome...