Your heat pump's auxiliary lockout and staging thresholds are likely set too aggressively. The system is defaulting to auxiliary heat before giving the heat pump a proper chance to work.
- Go to MAIN MENU > SETTINGS > INSTALLATION SETTINGS > THRESHOLDS > COMPRESSOR MIN OUTDOOR TEMP. The default is Disabled, which maximizes heat pump use. If it's set to a specific temperature, the heat pump won't run below that. Set it to Disabled or a lower temperature appropriate for your unit.
- Next, go to MAIN MENU > SETTINGS > INSTALLATION SETTINGS > THRESHOLDS > CONFIGURE STAGING MANUALLY > COMP TO AUX DELTA. This setting determines how many degrees the indoor temperature can drop below your setpoint before auxiliary heat engages. Increase this value. A higher number gives the heat pump more time to recover before aux kicks in.
IF THAT DIDN'T WORK: The heat pump itself might be short-cycling, which triggers auxiliary. Go to MAIN MENU > SETTINGS > INSTALLATION SETTINGS > THRESHOLDS > HEAT DIFFERENTIAL TEMP. Increase this value. This makes the system wait for a larger temperature drop before turning on, improving efficiency and reducing short cycles.
HEADS UP: Tweak one setting at a time and test for a day. Drastic changes can lead to comfort issues.