Emergency heat is a backup heating setting on heat pump systems. It forces your system to bypass the outdoor compressor and rely entirely on supplemental heating sources—like electric heat strips or a gas furnace—to warm your home.
Be careful not to activate EMERGENCY HEAT mode inadvertently, a very easy mistake to make. Using EMERGENCY HEAT or AUX mode can significantly increase your electric bill compared to regular HEAT mode. Only use these settings in true emergencies when you need immediate warmth.
Use the Emergency Heat (EM Heat) setting only when outdoor temperatures drop below 15°F to 25°F and your heat pump cannot keep the house warm, or if your outdoor unit breaks down.
Regular heat relies on your outdoor heat pump to extract warmth from the outside air, making it highly energy-efficient. Emergency heat bypasses the heat pump entirely and activates your system’s backup heating source (like electric strip heaters), which consumes significantly more energy.
You can run emergency heat continuously for days or even weeks if necessary, but it should only be used as a temporary safeguard. It bypasses your heat pump and relies completely on backup heat (usually electric heat strips), which will drastically increase your energy bills.
Yes, emergency heat uses significantly more electricity than your standard heat pump. It can consume up to 2 to 3 times more energy, which can cause your utility bill to skyrocket.
Effects on System Efficiency and Longevity
Emergency heat components aren't designed to run as the primary heat source for extended periods. Over time, prolonged use can lead to: Increased wear on electric resistance coils. Higher risk of element burnout.
It takes time for your home to warm up and cool down. If you're not sure how long it takes, try turning the heating on about 30 minutes before you need it. You should turn it off 30 minutes before you'll stop needing it.
Understanding the Costs
According to an article from Jones-Onslow Electric Membership Corporation (JOEMC), when your HVAC unit is operating in emergency heat mode, the cost of your heating bill goes up approximately $1.30 per hour.
Key Tips for Heat Pumps in Ice Storms Use Emergency Heat only in emergencies: If the unit is heavily iced, switch to "Emergency Heat" or "Auxiliary Heat" on your thermostat. This stops the outdoor fan from striking built-up ice and breaking.
Best winter thermostat settings for comfort and savings
Is Emergency Heat more expensive to run? If you have an all-electric heat pump, then the answer is a definite Yes! It is much more expensive to run your heat pump on Emergency Heat. And as the name implies, should only be run in an emergency until your heat pump can be repaired.
Conditions Where Your Heat Pump Ices Over: It's possible for the heat pump to ice over when it's really cold outside. If this happens and it does not defrost itself as usual, you should turn off the regular heat right away and use emergency heat until the ice melts or you can call an HVAC technician.
Auxiliary heat comes on automatically to assist your heat pump when it struggles to keep up with freezing temperatures. However, Emergency Heat must be turned on manually using your thermostat.
Heat pumps are meant to circulate comfort, not allergens, dust, or mold spores. Yet when they're dirty, they can turn your cozy home into a hotspot for headaches, congestion, and constant fatigue.
Heating and cooling (HVAC) systems are the biggest energy consumers in a typical house, accounting for roughly 45−50% of your total electricity usage. Water heaters, refrigerators, and lighting round out the rest of the major draws.
For most customers, we recommend turning on your furnace when the weather is consistently below 18° Celsius, which usually happens to be around the end of September, or early October. Some homeowners try to put off turning on their furnace as long as they can to save money, which is okay if you're healthy adults.
As easy as it is to turn on the emergency heat, most heating experts don't recommend using emergency heat unless you absolutely must, since it's much less efficient and can strain your heating system.
You can run emergency heat continuously for days or even weeks if necessary, but it should only be used as a temporary safeguard. It bypasses your heat pump and relies completely on backup heat (usually electric heat strips), which will drastically increase your energy bills.
Propane lanterns and candles also work well. Propane powered camping equipment, such as stoves and water heaters, are also convenient substitutes.
In most homes, Heating and Cooling (HVAC) systems drive the highest energy costs, accounting for nearly 40% to 50% of your total electricity bill. Following these, the appliances that run up your bill the most include water heaters, refrigerators, and laundry machines.
However, when temperatures plummet—typically between 30°F and 35°F—there is less ambient heat available to harvest. This is when your system's "brain" recognizes a need for help and engages the auxiliary heat to maintain consistent comfort.
Traditional and Fuel-Based Alternative Heat Sources