Ecobee Aux Heat Runtime Alert: What It Means & Fixes

An ecobee auxiliary-heat runtime alert means the thermostat recorded more backup-heat operation than the configured alert setting allows. That can be expected in some cold-weather or recovery conditions, but a new pattern of auxiliary-heat use can also point to a control, airflow, capacity, defrost, or equipment problem. A.J. LeBlanc Heating can compare the alert with actual system operation before changing settings.

What auxiliary heat actually is

Auxiliary heat is the backup stage controlled with the heat-pump system, often electric resistance heat or a fuel-burning furnace in a compatible dual-fuel design. A separate boiler or unrelated mini split is not automatically ecobee-controlled auxiliary heat.

When the alert may be expected

Auxiliary heat may run during cold weather, thermostat recovery, defrost, or another condition allowed by the system design. Alert menus and defaults vary by thermostat and software version. A new pattern, poor comfort, unusual noise, icing, or frequent backup operation in mild weather deserves diagnosis.

When the alert points at a real problem

Investigate (or call us) when the alert fires under conditions where the heat pump alone should be handling the load:

• Mild outdoor temperatures (40°F+): the heat pump should easily cover the home. Aux running often means a refrigerant issue, a defrost cycle problem, or an incorrect changeover setting.
• Aux running constantly even after a long warm-up period: may indicate the heat pump is undersized, has a refrigerant leak, or has a failed reversing valve.
• Aux running every time the system calls for heat: often a thermostat configuration issue where the system is treating the aux heat as primary.
• Sudden change in behavior: aux suddenly running far more than it used to with similar outdoor temperatures usually indicates the heat pump has degraded.

Review the alert and system settings

Alert menus and defaults can change by thermostat and software version. Use ecobee's current instructions for the installed model. Do not change compressor or auxiliary lockouts from the thermostat's advertised minimum operating temperature alone. The correct setting depends on the matched equipment's capacity and efficiency data, the home's load, backup capacity, rates, and manufacturer limits.

Why auxiliary heat may run

Backup operation can be influenced by outdoor conditions, thermostat recovery, equipment capacity, defrost, airflow, controls, and the configured changeover strategy. Electric resistance backup uses more electricity per unit of delivered heat than the heat pump under many operating conditions. The cost difference is not a fixed multiple because heat-pump performance changes with temperature and system operation.

Use settings designed for the system

Use thermostat settings that match the heat pump, backup equipment, controls, and household schedule. Do not select a compressor lockout from the advertised minimum operating temperature alone. Keep filters and outdoor-unit airflow maintained according to the equipment instructions.

Schedule heat-pump service

If the alert is new, frequent in mild weather, or paired with poor comfort, unusual noise, or icing, A.J. LeBlanc Heating can diagnose the equipment and review the thermostat configuration. Call 603-623-0412 to schedule heat-pump service.

Frequently Asked Questions

Should I disable the ecobee auxiliary-heat alert?

Review the alert and actual system operation before disabling it. Menus and defaults change, so use ecobee's current instructions for the installed model.

Is auxiliary heat normal in a New Hampshire winter?

It can be. Backup may run during cold weather, recovery, defrost, or another condition allowed by the system design. A new pattern or frequent use in mild weather deserves service.

What is the correct compressor lockout temperature?

It depends on the matched equipment's capacity and efficiency data, the home's load, backup capacity, energy rates, and manufacturer limits. There is no universal setting.

Why can electric resistance backup cost more to run?

Electric resistance backup uses more electricity per unit of delivered heat than the heat pump under many operating conditions. The cost difference is not a fixed multiple because heat-pump performance changes with temperature and system operation.