Code 109 — Low Indoor Temperature Alert: Zone 7 Allowing Aux Heat

What does 109 mean?

This alert indicates that Zone 7 is experiencing low indoor temperatures and the system is allowing auxiliary heating to engage to try and reach the setpoint. This could mean the primary heat source isn't keeping up.

• Outdoor temperatures are extremely low
• Thermostat setting in Zone 7 is too high for the primary heating capacity
• Poor insulation or air leaks in Zone 7
• Malfunction of the primary heating system (e.g., heat pump)

Click steps to track your progress.

1. 1

   Check the thermostat settings for Zone 7 to ensure it's not set excessively high.

2. 2

   Verify that all air vents in Zone 7 are open and unobstructed.

3. 3

   Ensure that the primary heating system (furnace or heat pump) is operating correctly.

4. 4

   If this happens frequently, consider improving insulation or sealing air leaks in Zone 7, or contact a technician to assess heating capacity.