Gas Furnace

Comprehensive Guide to Honeywell Gas Furnace Thermostat Configuration and Troubleshooting

Honeywell Gas Furnace Thermostat

How to Configure the Honeywell Gas Furnace Thermostat for Heat Pump and Electric Backup Heat?

To configure a Honeywell gas furnace thermostat to switch between a heat pump and electric backup heat, follow these step-by-step instructions:

  1. System Type Selection:
  2. Select the appropriate system type on your thermostat. For a heat pump with electric backup heat, you typically choose “Heat Pump with Backup or Auxiliary Heating” (usually setting 5).

  3. Ensure the thermostat is set to recognize the heat pump and the backup electric heat source.

  4. Wiring Configuration:

  5. Connect the necessary wires:

    • R: 24V power
    • W: Heat stage (for gas furnace or primary heat source)
    • W2: Auxiliary heat stage (for electric backup heat)
    • Y: Compressor (cooling)
    • Y2: Second stage cooling (if applicable)
    • G: Fan
    • O/B: Reversing valve (set to heating or cooling changeover as needed)
    • C: Common (ground).

  6. Backup Heat Settings:

  7. Set the backup heat source to electric heat. This is usually done in the thermostat settings menu where you specify the type of backup heat (e.g., electric, propane, or natural gas).

  8. Adjust the backup heat droop and upstage timer settings if available. These settings determine when the backup heat will engage based on temperature drops and time limits.

  9. Changeover Settings:

  10. Set the changeover mode to automatic if desired. This allows the thermostat to switch between heating and cooling set points automatically.
  11. Ensure the reversing valve is set correctly (heating or cooling changeover) based on the wiring and system configuration.

Example Settings:
– System Type: Heat Pump with Backup or Auxiliary Heating
– Backup Heat Source: Electric
– Backup Heat Droop: Set to a temperature difference (e.g., 2°F) below the set point before engaging backup heat
– Upstage Timer for Backup Heat: Set to a time limit (e.g., 90 minutes) before engaging backup heat if the primary heat source cannot reach the set point.

What is the Checklist for Optimal Heating and Cooling Performance?

Honeywell Gas Furnace Thermostat

To ensure optimal heating and cooling performance with your Honeywell gas furnace thermostat, follow this verification checklist:

  1. System Type:

  2. Ensure the correct system type is selected (e.g., Heat Pump with Backup or Auxiliary Heating).

  3. Mode Selections:

  4. Verify that the thermostat is set to the correct mode (heat, cool, or auto) based on the current needs.

  5. Temperature Settings:

  6. Set the heating and cooling set points according to your preferences.

  7. Ensure the temperature differential between heating and cooling set points is reasonable (e.g., 2-3°F).

  8. Wiring and Connections:

  9. Double-check all wire connections to ensure they match the system configuration and thermostat requirements.

  10. Fan Settings:

  11. Ensure the fan settings are correct for your system (e.g., gas or oil heat vs. electric heat).

  12. Calibration:

  13. If necessary, calibrate the thermostat to ensure accurate temperature readings and proper system operation.

Why Does the Thermostat Keep Switching to Emergency Heat Mode?

There are several reasons why a Honeywell gas furnace thermostat may keep switching to emergency heat mode:

  1. Incorrect System Type:

  2. If the system type is not set correctly, the thermostat may default to emergency heat mode.

  3. Insufficient Primary Heat Source:

  4. If the primary heat source (heat pump) is unable to maintain the set temperature, the thermostat may switch to backup heat (emergency heat mode).

  5. Faulty Wiring or Connections:

  6. Incorrect or loose wiring connections can cause the thermostat to malfunction and switch to emergency heat mode.

  7. Defrost Mode:

  8. During defrost cycles, the heat pump may temporarily switch to backup heat to maintain indoor temperature.

Troubleshooting Steps:

  1. Verify System Type and Settings:

  2. Ensure the correct system type and backup heat settings are selected.

  3. Check Wiring:

  4. Inspect and verify all wire connections are secure and correct.

  5. Adjust Backup Heat Settings:

  6. Adjust the backup heat droop and upstage timer settings to prevent unnecessary switching to emergency heat mode.

  7. Outdoor Temperature:

  8. If the outdoor temperature is very low, the heat pump may not be efficient enough, causing the thermostat to switch to backup heat. Consider adjusting the changeover settings based on outdoor temperature.

Reference Links

  1. Honeywell Thermostat Instructions, Wire Terminals, Functions, Color Codes:

  2. Honeywell Thermostat Instructions

  3. New Honeywell Thermostat Install:

  4. New Honeywell Thermostat Install

  5. Thermostat Setup for Heat Pump, Electric Furnace or Gas Backup:

  6. Thermostat Setup for Heat Pump

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