Why Is My Ecobee Running Auxiliary Heat So Much and How Do I Fix It?
- Aux heat threshold too low
- Heat pump undersized
- Outdoor temperature too cold
Problem Description
Ecobee running auxiliary heat too often means expensive electric resistance heating activates when heat pump should handle heating. This dramatically increases energy bills.
Symptoms
- Aux Heat running constantly
- High electricity bills
- Aux Heat icon always on
- Heat pump not keeping up
- Emergency heat being used
- Ecobee shows AUX in heating
Recognize these? Here's what usually causes it.
Common Causes
- Aux heat threshold too low
- Heat pump undersized
- Outdoor temperature too cold
- Heat pump low on refrigerant
- Defrost cycle confusion
- Compressor lockout temp setting
Most fixes happen in the first 3 steps.
If heat pump refrigerant is low, aux heat will run excessively. Have HVAC tech check refrigerant levels and for leaks.
Step-by-Step Solution
Adjust Aux Heat Max Temp
Go to Settings > Installation Settings > Thresholds. Increase Aux Heat Max Outdoor Temperature. Lower setting means aux heat only kicks in when very cold outside.
Check Temp Differential
In Thresholds, set Aux Heat to come on only when temp is more than 2-3F below setpoint. Default is often too sensitive at 1F.
Lower Compressor Lockout
Heat pumps work down to about 25-30F. Set Compressor Min Outdoor Temp to 25F or lower to maximize heat pump use before aux heat.
Check Heat Pump Performance
Go outside when heating. Listen for compressor running. Feel lines - should be warm. No heat from outdoor unit means heat pump needs service.
Enable Aux Runtime Alert
In ecobee app, enable alert for aux heat running too long. This notifies you of potential heat pump problems or settings issues.
Quick Solutions
Still having issues? This is usually the deeper cause below.
If this comes back after following these steps, check whether a recent app or firmware update reset a default setting — the fix works, but the setting gets reverted silently.
Some aux heat use is normal in very cold weather. Concern is when aux runs above 40F outdoor temp or for many hours.
This issue almost always looks more complex than it is — the majority of cases trace back to a single setting, a stale credential, or a default that shipped wrong.
- Aux heat threshold too low
- Heat pump undersized
- Outdoor temperature too cold
- Heat pump low on refrigerant
- Defrost cycle confusion
Before you go — try one of these (they fix most cases).
Most popular upgrades chosen by Ecobee Thermostat owners.
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Official Manufacturer Manual
Ecobee provides official product documentation through their online manual rather than downloadable PDF. Access setup guides, troubleshooting steps, and product specifications for your Ecobee Thermostat.
Source: ecobee.com
Need More Help? Ecobee Support
Note: The contact information below connects you directly to Ecobee's official customer support team, not Trunetto. They can help with warranty claims, device replacements, and advanced technical issues.
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