Ecobee Aux Heat Runtime Alert

Ecobee's Aux Heat Runtime Alert notifies you when your heat pump's auxiliary (backup) heat has run continuously for a set number of hours. The default threshold is 3 hours. For a heat pump in southern New Hampshire, hitting that threshold during a cold snap is often completely normal. But if the alert fires on a mild 45°F day, when the heat pump alone should be carrying the load, it may be pointing at a real problem worth investigating.

Here is what the alert means, when to ignore it, and when to call us.

What auxiliary heat actually is

Auxiliary (or backup) heat is the secondary heat source that takes over when the heat pump alone cannot keep up. On NH installations it is typically:

• Electric resistance strips built into the air handler (most common with all-electric heat pump installs)
• A gas, propane, or oil furnace in a dual-fuel configuration
• The existing boiler in homes where a mini split heat pump is paired with hydronic heat

Aux heat is much more expensive to operate than the heat pump itself. Electric resistance in particular costs roughly 3 times what the heat pump costs to deliver the same heat, which is why a runtime alert exists in the first place.

When the alert is normal

The alert fires when aux heat runs longer than the threshold (default 3 hours). This is expected behavior on many NH winter days:

• The outdoor temperature is below the heat pump's effective range
• You are recovering from a setback in extreme cold
• The home is in a long cold-snap stretch where the heat pump cannot keep up alone

For homes with cold-climate heat pumps and well-tuned controls, the compressor lockout is usually set somewhere between 15°F and 30°F outdoor temperature, depending on the heat pump's capacity and the home's heat loss. Below the compressor lockout temperature, only the aux heat runs, and the alert fires often.

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.

How to adjust the alert threshold on an Ecobee

To change the Aux Heat Runtime Alert threshold:

1. Open the hamburger menu (3 horizontal lines) at the bottom left of your Ecobee thermostat or in the Ecobee app.
2. Go to Reminders & Alerts.
3. Select Preferences.
4. Select Aux Heat Runtime Alert.
5. Choose a longer threshold (5 hours, 8 hours, etc.) or select Disable.

For most NH homes, increasing the threshold to 5 to 8 hours reduces nuisance alerts during normal cold-weather operation while still flagging genuinely abnormal aux runtime.

Why your auxiliary heat runs (the three drivers)

1. Compressor lockout temperature

If the outdoor temperature is below the configured compressor lockout temperature, the Ecobee disables compressor (heat pump) operation and runs aux heat only. We typically set the compressor lockout between 15°F and 30°F, depending on the heat pump's rated low-temperature capacity and the home's insulation level.

2. Time-based algorithm

Ecobee uses an algorithm that watches how long the heat pump has been running and whether indoor temperature is making progress. If the heat pump runs for an extended period without recovering setpoint, the thermostat will call for aux heat to help.

3. Temperature delta

If you raise the setpoint by a large amount (say from 65°F to 72°F), Ecobee may bring on aux heat to recover quickly rather than waiting for the heat pump alone to make up the gap. Heat pumps run most efficiently at a steady setpoint; large changes are what trigger aux heat unnecessarily.

How to minimize aux heat use

• Keep the thermostat at a steady setpoint rather than large setbacks. Heat pumps love steady; they pay an efficiency penalty for big recoveries.
• Set the compressor lockout temperature appropriately for your heat pump model. A unit rated to -13°F should not be locked out at 30°F.
• Confirm the thermostat is configured correctly for your equipment type (heat pump, dual-fuel, with auxiliary heat strip or external furnace).
• Make sure the heat pump itself is properly maintained: clean coils, correct refrigerant charge, clear of snow buildup.

Schedule a heat pump tune-up

If your Aux Heat Runtime Alert is firing under conditions where it should not, or you want a professional to confirm your thermostat is configured optimally for your heat pump, contact A.J. LeBlanc Heating. Serving New Hampshire families since 1928.

Frequently Asked Questions

How do I disable the Ecobee Aux Heat Runtime Alert?

Open the hamburger menu, go to Reminders & Alerts > Preferences > Aux Heat Runtime Alert, and select Disable. Increasing the threshold to 5 or 8 hours is usually a better choice than fully disabling it.

Is it normal for aux heat to run in New Hampshire winter?

Yes, especially below the heat pump's compressor lockout temperature (typically 15 to 30°F) or during long cold snaps. The alert is informational, not necessarily a problem.

What is a good compressor lockout temperature for my heat pump?

Depends on the heat pump's low-temperature capacity and the home's heat loss. Cold-climate heat pumps with strong sub-zero capacity can have the compressor lockout set as low as 5 to 15°F. Standard heat pumps may need a compressor lockout closer to 30°F.

Why does aux heat cost so much more?

Electric resistance heat delivers exactly 1 unit of heat per 1 unit of electricity. A heat pump delivers 2 to 3 units of heat per 1 unit of electricity at typical NH winter conditions. So aux heat costs roughly 2 to 3 times what the heat pump costs for the same heat output.

Should I keep my thermostat at a steady temperature with a heat pump?

Yes, usually. Heat pumps work best at steady setpoints. Large setbacks force the system into aux heat for recovery, which often erases the savings the setback was supposed to produce. Modern smart thermostats configured for heat pumps handle modest setbacks intelligently.