Auxiliary (Aux) heat, also referred to as second-stage heating, serves as a supplementary or backup heating system. It activates when your primary heating system fails to achieve your set temperature (based on runtime & temperature difference) due to extreme weather conditions.
The secondary system can be electric strips or a furnace/boiler (fossil-fuel-based systems). Since these systems use significantly more energy than the primary heating source (heat pump), it’s best to limit their runtime and adjust the thermostat threshold settings to minimize auxiliary heat usage.
Temperature Thresholds
Temperature Difference Heat Pump to Aux
It refers to the temperature difference between your setpoint and the home temperature. If this difference is greater than your set value, your thermostat will switch to auxiliary heating. This helps in achieving your preferred temperature by turning on the aux when the heat pump alone can’t efficiently close the gap.
Example:
- Set point: 68°F
- Current home temperature: 58°F
- Temperature difference: 10°F
If your Heat Pump to Aux threshold is set to 9°F:
- Since the temperature difference of 10°F exceeds the 9°F threshold, auxiliary heating will be used until the gap is narrowed.
- Once the temperature rises to 59°F (within the 9°F threshold), the auxiliary heat will shut off.
- From that point onward, the heat pump will continue to bring the temperature up to the 68°F set point.
The larger the threshold value you set, the longer it will take for your auxiliary heat to kick in. We recommend setting it to 9°F for maximum savings.
Temperature Difference Stage 2
This is the temperature difference between the indoor temperature and the setpoint before stage 2 is activated, helping stage 1 achieve the setpoint. Setting a higher number will result in savings because stage 1 may not be activated frequently. We recommend setting it to 10°F.
📢 Important
- The Temperature Difference Heat Pump to Aux & Temperature Difference Stage 2 are interconnected. Modifying one value will impact the other.
- If you have disabled simultaneous operation of the heat pump and aux, the heat pump will turn off, and only aux will run.
Maximum Outdoor Temperature
It is the maximum outdoor temperature above which the auxiliary heat will not operate, and a heat pump will be used to achieve your set point.
📢 Important
- The thermostat installation address is required to fetch outdoor weather data.
- The thermostat requires a working internet connection to receive updated weather information.
Operational Timers
Maximum Runtime Heat Pump to Aux
It is the amount of time your heat pump runs before switching to Aux heat. It’s best to set this time to 50 minutes for reduced aux usage.
Note: If you have enabled Aux to Heat Pump, this option will not be applicable. You can disable it in the Equipment Stage Control section.
Maximum Runtime Stage 1
It is the maximum runtime of stage 1 heating before it switches to stage 2 of the compressor. Set it to 60 minutes for savings.
Note: If you have engaged the Aux Control, this option will not be applicable. You can disable it in the Equipment Stage Control Section.
Minimum On Time
This is the minimum time the auxiliary heating will run. We recommend using the default settings.
Adjusting Threshold Settings On Cielo Smart Thermostat
Here are some adjustments you can make on your Cielo Smart Thermostat to minimize the use of Aux heat:
Step 1: Go to 'Menu' and select 'HVAC Settings'.
Step 2: Select ‘Threshold Settings’.
Step 3: Tap ‘Advanced’.
Step 4: Tap ‘ Auxiliary Heat’.You will find a list of settings that you can adjust to reduce Aux usage and save on your energy bills.
Adjusting Threshold Settings On Cielo Home App
Step 1: On the Control Screen, tap on the ‘Settings’ icon at the top right corner.
Step 2: Tap on ‘HVAC Settings’.
Step 3: Tap on ‘Threshold Settings’.
Step 4: Then tap on ‘Change Settings’ in the Advanced option.
Step 5: Tap on ‘Auxiliary Heat’. You will find a list of settings that you can adjust to reduce Aux usage and save on your energy bills.
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