Honeywell TH4210D1005 Thermostat Reset Guide


The Honeywell TH4210D1005 thermostat is a reliable and efficient device that helps you maintain a comfortable indoor environment while also saving on energy costs. However, there may come a time when you need to reset it due to issues like incorrect settings, unresponsive controls, or other technical glitches. In this guide, we will walk you through the steps to reset the Honeywell TH4210D1005 thermostat.

Why Reset the Honeywell TH4210D1005 Thermostat?

Before we delve into the reset process, it’s essential to understand why you might need to reset your thermostat:

  1. Incorrect Settings: Sometimes, incorrect or confusing settings can lead to uncomfortable indoor temperatures or higher energy bills. Resetting your thermostat can help start with a clean slate.
  2. Unresponsive Controls: If the thermostat becomes unresponsive or fails to display any information, a reset can often resolve the issue.
  3. Troubleshooting: When you encounter technical problems with your thermostat, resetting it can be an important step in the troubleshooting process.

Resetting the Honeywell TH4210D1005 Thermostat

To reset the Honeywell TH4210D1005 thermostat, follow these steps:

1. Turn Off the Power:

  • Locate the main power switch or circuit breaker that supplies power to your HVAC system.
  • Turn off the power by flipping the switch or using the circuit breaker.

2. Remove the Thermostat from the Wall:

  • Gently pull the thermostat body away from the wall mounting plate.
  • Ensure that you disconnect it from the mounting plate by removing it from the latch or prying it off.

3. Disconnect the Wires:

  • Take a picture of the wiring for reference, so you can reconnect them correctly.
  • Carefully disconnect the wires from the thermostat.

4. Wait for 30 Seconds:

  • Allow the thermostat to remain disconnected for at least 30 seconds. This helps clear the memory and settings.

5. Reconnect the Thermostat:

  • Reconnect the thermostat to the wiring.
  • Attach the thermostat body back onto the wall mounting plate, ensuring it latches securely.

6. Restore Power:

  • Turn the power back on using the main power switch or circuit breaker.

7. Reconfigure Settings:

  • The thermostat will now reset to its default settings. You will need to reconfigure it according to your preferences.


Resetting the Honeywell TH4210D1005 thermostat can help resolve various issues related to incorrect settings, unresponsiveness, or technical glitches. By following these steps, you can ensure that your thermostat operates efficiently, providing you with a comfortable and energy-efficient indoor environment. If you continue to experience problems after the reset, consider consulting a professional HVAC technician for further assistance.