Thermostat shows "Aux Heat" or emergency heat running too often on a heat pump system

Safety first: Turn off power to the HVAC system at the breaker before adjusting wiring.

Steps to troubleshoot:

• 1. Review setpoints: Avoid large temperature setbacks (more than 3–4°F) which can trigger Aux heat to recover quickly.
• 2. Check configuration: In installer setup, ensure the system is configured as a heat pump with auxiliary heat and that Aux/E is correctly assigned.
• 3. Adjust Aux lockout (if available): Set an outdoor temperature lockout or balance point so Aux heat only runs when necessary.
• 4. Verify Aux wiring: Confirm the Aux/E wire is connected to the correct terminal at both the thermostat and air handler.
• 5. Monitor operation: After changes, observe several days of operation to see if Aux usage decreases.

When to call a professional: If Aux heat still runs excessively, an HVAC technician should verify heat pump performance and thermostat configuration.