You rarely need to switch your heat pump to auxiliary heat manually. Modern thermostats handle this automatically. However, the auxiliary (or secondary) heat will trigger automatically when:
Auxiliary (aux) heat should generally come on automatically when outdoor temperatures drop below 𝟑𝟓 ∘𝐅 to 𝟒𝟎 ∘𝐅. This threshold—known as the "balance point"—is when your heat pump struggles to extract enough warmth from the outside air and requires supplemental backup heat to maintain your indoor temperature.
Double-check the thermostat, ensuring it's set to "heat" and the desired temperature. Check for a power switch near the heat pump system. Not every system has one, but if you do, make sure it's turned on. Check the heating elements in the auxiliary heater.
When should auxiliary heat come on? Your auxiliary heat, or secondary heat source, should come on when your heat pump is struggling to heat your home effectively. The thermostat will trigger auxiliary heat when: The outside temperature is below 40 degrees or a set aux heat trigger temperature.
How often should auxiliary heat come on? Auxiliary heat should come on only occasionally, such as during extremely cold temperatures or when the system is trying to raise the temperature quickly.
No, you should not leave auxiliary (aux) heat on all the time. Aux heat (like electric resistance strips) is significantly more expensive to run than a standard heat pump. Leaving it on constantly will cause a massive spike in your utility bills.
The "30-minute heating rule" is a highly efficient, money-saving thermostat strategy that involves turning your heating system on 30 minutes before you need a space warmed up, and turning it off 30 minutes before you no longer need it.
Aux heat and the heat pump should run simultaneously if the aux heat is electric resistance (heat strips). If aux heat is a furnace, the aux and heat pump should NOT run simultaneously.
Under normal conditions, auxiliary heat (the backup heat source for a heat pump) should only run for 15 to 30 minutes at a time. It is meant to provide a quick boost to warm your home when it is too cold outside for the heat pump to work efficiently on its own.
Is it bad if auxiliary heat comes on? No, it's normal during very cold weather or rapid temperature recovery. Frequent use in mild weather, however, may indicate a system issue.
In mild winter weather, a heat pump should typically run for 2 to 3 hours a day, cycling on and off in short intervals. However, in freezing temperatures (below 30°F), it is perfectly normal for the system to run constantly or nearly 24/7 to maintain a steady temperature.
The "20-degree rule" for heat pumps and air conditioners refers to the recommended limit on the temperature difference between the outside air and the indoor air. During summer, experts advise that you do not set your thermostat more than 20 degrees cooler than the outdoor temperature.
This can cause concern, as auxiliary heat typically is not supposed to run all the time. While it's normal for auxiliary heat to kick in during exceedingly cold temperatures, running it too long may indicate an issue with the heat pump.
Emergency heat has to be manually switched on and should only be used in temperatures below 30 degrees. In contrast, auxiliary heat turns on automatically to help heat your home more quickly if there is a sudden drop in temperature.
Is it bad if auxiliary heat comes on? No. It simply means your HVAC system is changing how it heats your home. However, if aux heat comes on and stays on even when outdoor temperatures are above your aux heat trigger temperature, you should call for HVAC service.
No, it is not bad. Auxiliary (or "backup") heat turning on during winter is a normal, designed feature of a heat pump. It operates like a safety net, kicking in when it is too cold outside for your heat pump to warm your home efficiently on its own.
Yes, auxiliary heat significantly increases your electric bill. It acts as an electric resistance heater (like a giant hair dryer) and consumes about 2× to 3× more electricity than your heat pump's normal operation.
When the weather outside gets colder than your lockout temperature, your thermostat will start using AUX heat. If you have a heat pump with AUX heat, your Nest thermostat will use Heat Pump Balance to determine your lockout or breakpoint temperature automatically.
Auxiliary heat kicks on automatically when your heat pump struggles to warm your home efficiently on its own. This backup system usually activates in three specific scenarios:
A properly functioning heat pump should cycle on and off 2 to 3 times per hour, with each cycle lasting between 10 and 15 minutes. Unlike traditional furnaces, heat pumps are designed to run for longer periods at lower speeds to maintain a steady, comfortable temperature.
Think of the emergency heat setting as a backup plan for a malfunctioning heat pump—not something to use just because it's cold outside. Turning on your emergency heat unnecessarily can increase energy costs by two to three times, making it one of the most expensive heating mistakes homeowners make.
Known for his practical tips, Lewis introduced the '4pm rule' which involves using curtains strategically to retain heat. He suggests opening curtains when the sun rises at around 8:30am to let in natural warmth, and closing them by 4pm to keep the heat inside.
In most homes, heating and cooling (HVAC) runs up your electric bill the most, accounting for about 40% to 50% of your total energy use.
No, October is generally not too early. HVAC professionals and energy experts usually recommend turning the heat on when your indoor temperature drops consistently below 65∘𝐹, or when it's just plain uncomfortable.