Honeywell TH5110D Non-Programmable Thermostat Operating Instructions

This document provides comprehensive operating instructions for the Honeywell TH5110D Non-Programmable Thermostat.

Features

Large, Clear, Backlit Display: Easy-to-see and read—even in the dark.
Precise Comfort Control: ±1°F 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 Diagram

The thermostat features a clear digital display. Key components are labeled: BATTERY HOLDER LATCH (press to release), BATTERY HOLDER (holds two AAA alkaline batteries), TEMPERATURE SETTING BUTTONS (to raise or lower the temperature), FAN BUTTON (selects Auto or On), and SYSTEM BUTTON (selects Heat, Off, Cool, or Auto).

Display Explained

The digital display shows 'Inside' temperature, a 'Replace Battery' indicator, the 'Heat/Cool Setting', 'Fan' status (On/Auto), 'System' status (Heat On, Cool On, Heat Cool AutoOff), the current fan setting, and the current system setting. It also indicates when the thermostat is 'CALLING' for heat or cool.

Operate Your Thermostat

Set System Setting

Press the System button to select one of the following modes:

Heat: Thermostat controls the heating system.
Off: Both heating and cooling systems are off.
Cool: Thermostat controls the cooling system.
Auto: Thermostat automatically changes between heating and cooling operation based on indoor temperature. Refer to the Auto Changeover section for details.

⚠️ CAUTION: Equipment Damage Hazard. Air conditioning compressor damage is possible. Do not operate the cooling system when the outdoor temperature is below 50°F (10°C).

(Diagram description: A hand is shown pressing the System button to select Heat, Off, Cool, or Auto.)

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 for improved air circulation or more efficient air cleaning.

(Diagram description: A hand is shown pressing the Fan button to select Auto or On.)

Change Temperature Setting

Press the Up or Down button to select the desired temperature setting. The first press of the Up or Down button turns on the backlight; the second press changes the temperature setting.

Temperature Setting Range:

HEAT: 40°F to 90°F (4.5°C to 32°C)
COOL: 50°F to 99°F (10°C to 37°C)

(Diagram description: A hand is shown pressing the Up or Down temperature setting buttons. The display shows the temperature setting being adjusted. The diagram also indicates the temperature setting range.)

Replace Batteries

When the "Replace Battery" indicator flashes in the display, replace batteries promptly with two fresh AAA alkaline batteries.
Press the battery holder latch to release the battery holder.
Remove the battery holder from the thermostat.
Remove the old batteries and insert two fresh AAA alkaline batteries as marked on the battery holder. Ensure correct battery orientation.
Insert the battery holder back into the thermostat as shown.

? Tip: The thermostat does not lose any settings when the batteries are replaced; all settings are permanently stored in memory.

(Diagram descriptions: Multiple diagrams illustrate releasing the battery holder latch, removing the holder, inserting new batteries with correct polarity, and reinserting the holder.)

Review Battery Tips

Replace batteries as soon as the "Replace Battery" indicator flashes. This indicator typically flashes two months before the batteries completely run down.
Always use fresh AAA alkaline batteries. Non-alkaline batteries may not last as long and could leak, potentially damaging the thermostat.
Replace batteries once per year to prevent the thermostat and heating/cooling system from shutting down due to low battery power. This also helps prevent battery leakage.
As a precaution, replace batteries when leaving your home for more than a month to ensure your heating/cooling system continues to operate.

Built-in Compressor Protection

The TH5110D Thermostat includes built-in compressor protection, known as a minimum-off timer. This feature prevents the compressor from restarting too soon after a shutdown.

The minimum-off timer activates once the compressor turns off. If there is a demand for heating or cooling during this timer period, the thermostat will flash "Cool On" or "Heat On"^a on the display.

Once the minimum-off timer expires, "Cool On" or "Heat On"^a will appear solidly on the display, and the compressor and fan will turn on.

^a Applies to Heat Pumps only.

Auto Changeover

Auto Changeover is a feature designed for climates where both air conditioning and heating are used on the same day. The "Auto" setting is only available if your heating and air conditioning dealer has configured the thermostat for this feature. In some installations, "Auto" might be the only system selection available.

The following describes how to change cool and heat temperature settings when the system is set to Auto.

When adjusting the temperature setting, if "▲Cool" or "▼Heat" appear in the display, the temperature setting for the opposite mode is also being adjusted. The thermostat maintains a three-degree difference between the cool and heat temperature settings (known as deadband), which is not adjustable.

To set Auto Changeover:

Press the System button to change the System setting to Auto. (Diagram description: A hand presses the System button to set the system to Auto.)
Press the Up or Down button to raise or lower the cool temperature setting.
Press the Select Heat/Cool button to display the Heat temperature setting. The text "Select Heat/Cool" will flash for six seconds. (Diagram description: A hand presses the Select Heat/Cool button.)
Press the Up or Down button to raise or lower the heat temperature setting.
After the last button press, "Select Heat/Cool" stops flashing after six seconds. The thermostat then returns to displaying "Auto" for the System setting. (Diagram description: A hand presses the temperature setting buttons while "Select Heat/Cool" is flashing.)

? Tip: The "Auto" setting is only available if your heating and air conditioning dealer has set up Auto Changeover.

Replacement Part

Replacement Battery Holder:

Part number: 50000951-001 Battery Holder.

To order, contact your heating and air conditioning dealer or call Honeywell Customer Care at 1-800-468-1502.

(Diagram description: An illustration of the battery holder is shown.)

Troubleshooting Tips

If . . .	Then . . .
Display is blank.	Check the circuit breaker to ensure it is not tripped. Check the power switch at the heating and/or cooling system to ensure it is on. Check the furnace door to ensure it is closed securely. If using batteries, verify that fresh AAA alkaline batteries are installed correctly in the battery holder.
Temperature settings do not change.	Verify temperature settings are within the operational range: Heating 40°F to 90°F (4.5°C to 32°C); Cooling 50°F to 99°F (10°C to 37°C).
Heating system does not turn on.	Set the system to Heat by pressing the System button. Ensure the heat temperature setting is above the room temperature and "Heat On" is displayed solidly. Check the circuit breaker to ensure it is not tripped. Check the power switch at the heating and/or cooling system to ensure it is on. Check the furnace door to ensure it is closed securely. Wait approximately five minutes for the heating system to respond. If all checks are complete and the issue persists, contact your local heating and cooling contractor.
Cooling system does not turn on.	Set the system to Cool by pressing the System button. Ensure the cool temperature setting is below the room temperature and "Cool On" is displayed solidly. Check the circuit breaker to ensure it is not tripped. Check the power switch at the heating and/or cooling system to ensure it is on. Check the furnace door to ensure it is closed securely. Wait approximately five minutes for the cooling system to respond. If all checks are complete and the issue persists, contact your local heating and cooling contractor.
"Heat On" is not shown in the display.	Set the System to Heat and ensure the temperature setting is above the room temperature. If "Heat On" is displayed solidly but the heating system does not activate, refer to the "Heating system does not turn on" section.
"Cool On" is not shown in the display.	Set the System to Cool and ensure the temperature setting is below the room temperature. If "Cool On" is displayed solidly but the cooling system does not activate, refer to the "Cooling system does not turn on" section.
"Heat On" is flashing in the display (heat pumps only).	Compressor minimum-off timer is active. Wait up to five minutes for the heating system to turn on.
"Cool On" is flashing in the display.	Compressor minimum-off timer is active. Wait up to five minutes for the cooling system to turn on.

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. These can be found on the thermostat battery holder.

(Diagram description: An illustration shows the thermostat battery holder with labels pointing to the locations for the MODEL NUMBER and DATE CODE.)

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