Knowing when should you use emergency heat is essential for every homeowner aiming to keep their home comfortable and energy efficient. With fluctuating outdoor temperatures and the risk of a malfunctioning heat pump, understanding the role of emergency heat can help you avoid unnecessary expenses and maintain a reliable heating system.

This guide explains the ins and outs of your heat pump, how emergency heat functions, and when you should rely on it—highlighting the benefits of regular professional HVAC maintenance for long-term comfort and efficiency.

Understanding Heat Pumps and Emergency Heat

Outdoor heat pump units covered in snow, illustrating winter conditions where emergency heat may be necessary.
Snow-covered heat pump units like these may struggle to extract heat efficiently in freezing conditions. When the system can’t pull enough warmth from the outdoor air, auxiliary or emergency heat may activate to keep the home comfortable.

Heat pumps are remarkable devices that extract heat from outdoor air and transfer it indoors, making them highly energy efficient—often 2-4 times more efficient than traditional electric resistance heat. However, when temperatures drop too low, your heat pump might struggle to pull in enough heat, and that’s when the emergency heat setting becomes essential.

  • What is Emergency Heat?
    Emergency heat is a backup heating system activated when your primary heat pump fails or is insufficient due to extremely cold weather. It typically uses an electric heat strip (or sometimes runs on natural gas or oil) to warm your home.
  • Efficiency Comparison:
    While a heat pump can be 200% to 400% efficient in mild weather, auxiliary heat—typically used to supplement the system in colder conditions—and emergency heat, activated during true emergency situations, operate at around 100% efficiency. This means they use one unit of electricity to produce one unit of heat, making them far less efficient than the heat pump itself and significantly more expensive to run over time.

How Emergency Heat Works

When your thermostat detects that your home isn’t reaching the desired temperature and the outdoor air is too cold, it may activate emergency heat mode. Here’s how it works:

  • Activation Process:
    The thermostat shuts off the outdoor heat pump and switches to a backup heating source. This backup system, often an electric heat strip on the air handler, provides the needed warmth until your primary system is repaired.
  • Operation Details:
    The emergency heat setting runs continuously until it’s manually turned off, ensuring your home remains warm during a heating emergency. It also prevents potential damage to the heat pump compressor by avoiding overstraining in harsh conditions.

When is Emergency Heat Necessary?

Emergency heat should be used exclusively during critical situations:

  • Heat Pump Malfunctions:
    If your heat pump stops heating your home due to damage, ice buildup, or mechanical failure, switching to emergency heat becomes essential.
  • Extreme Cold Conditions:
    In freezing temperatures or during an ice storm, when the heat pump is frozen or unable to extract sufficient warmth from the outdoor air, emergency heat is a necessary safeguard.

Avoiding Unnecessary Use

It’s important not to activate emergency heat simply because it’s cold outside.
Most modern heat pumps are efficient enough to handle outdoor temperatures above 30°F to 35°F without switching to emergency mode. Using emergency heat unnecessarily can lead to a significant increase in your energy bill.

The Cost of Running Emergency Heat

Running your heating system in emergency heat mode is considerably more expensive than operating your regular heat pump:

  • Energy Consumption:
    Emergency heat relies on a less efficient backup system, such as an electric heat strip, which can increase energy usage.
  • Monetary Impact:
    Homeowners may see an increase of up to $20 per day on their energy bills when emergency heat is in use. This added cost is why it is best to limit the use of emergency heat to true emergencies.

Energy Efficiency Tips

Modern digital thermostat set to 70 degrees, used to control HVAC and emergency heat settings in a home.
Setting your thermostat between 68°F and 70°F helps your heat pump operate efficiently and avoids triggering auxiliary or emergency heat unnecessarily, keeping your energy bills in check.

Keeping your HVAC system energy efficient starts with smart daily use. While heat pumps are designed to perform well, small decisions can have a big impact on your electric bill and comfort level. Here are some practical ways to reduce energy use and avoid unnecessary heating costs:

  • Set your thermostat between 68°F and 70°F: This range helps your main heat pump maintain indoor comfort efficiently without frequently switching to aux heat or EM heat.
  • Avoid frequent temperature changes: Rapid adjustments can confuse your HVAC system and trigger supplemental heating, leading to higher energy bills.
  • Use a programmable or smart thermostat: It maintains a consistent actual indoor temperature and prevents unnecessary activation of the EM heat setting.
  • Let your heat pump do the work: Most heat pumps can pull heat from the outside air efficiently down to 30°F–35°F. Don’t assume you need to switch to backup heat just because it’s cold outside.
  • Monitor outdoor temperature and system behavior: If your home isn’t staying warm and the outside temperature is above freezing, it could be a sign of an issue with your main heat pump.

Using these strategies helps reduce reliance on auxiliary or EM heat, lowers your electric bill, and ensures your HVAC system delivers enough warmth to keep your family comfortable.

Common Mistakes to Avoid

Many homeowners unintentionally misuse their heating systems, leading to higher heating bills and lower system efficiency. Here are some of the most common mistakes:

  • Activating EM heat without a true emergency: The EM heat setting shuts off your main heat pump and forces your system to rely on backup heat, which is far less efficient and raises your heating bill significantly.
  • Cranking the thermostat to heat faster: Doing this often triggers supplemental heating or backup heating elements, which increases your electric bill without making your home warm any faster.
  • Confusing system types: Many homeowners don’t realize that different systems behave differently. For example, all electric systems are more prone to engaging emergency heat, while homes with a gas furnace or backup gas furnace may not need to rely on electric strips.
  • Overreacting to a temporary cold: Some homeowners turn on EM heat just to keep their family warm quickly, not realizing the HVAC system can manage the load if given time to work as designed.

Avoiding these errors will help keep your heating system efficient, protect your wallet, and prevent unnecessary use of EM heat.

HVAC Maintenance Matters

Preventive maintenance is the most effective way to avoid relying on emergency heat and to ensure your HVAC unit performs efficiently in freezing temperatures. A professional HVAC inspection should include the following:

  • Inspecting the indoor unit: This includes cleaning filters, checking the air handler, testing thermostat accuracy, and ensuring proper communication between components.
  • Checking the outdoor unit: A frozen or blocked outdoor unit can cause the heat pump to fail. If the heat pump freezes, your system may switch to EM heat automatically, increasing energy usage.
  • Testing the backup heating element and secondary heating source: These include electric furnaces or a backup gas furnace. A technician should verify that they are functioning correctly in case they need to take over when the main system fails.
  • Full system performance testing: An HVAC professional should assess how the entire HVAC system operates under winter conditions to ensure it provides enough warmth without defaulting to emergency heat.

Staying on top of HVAC maintenance helps you avoid emergency heat cost spikes, keeps your heating equipment working properly, and prepares your system for whatever the winter brings.

Best Practices for Using Emergency Heat

For optimal home comfort and energy efficiency, follow these guidelines:

  • Use Only in Emergencies:
    Activate emergency heat only when your primary heat pump is damaged, frozen, or unable to maintain the desired temperature.
  • Switch Back Promptly:
    Once repairs are complete or the outdoor temperature improves, turn off emergency heat to prevent unnecessary energy consumption.
  • Regular HVAC Maintenance:
    Regular inspections by trusted experts can preempt many common issues, keeping your system running efficiently and reducing the need for backup heating.
  • Understand Your System:
    Familiarize yourself with your heat pump thermostat and backup heating system settings so you know exactly when and how to switch modes during a heating emergency.

Keep Your Home Warm and Your Energy Bills in Check

Staying informed about when you use emergency heat is key to managing your home’s heating system effectively. By understanding the mechanics behind your heat pump, recognizing the signs of a malfunction, and relying on professional maintenance like that from Bob’s Repair, you can ensure a warm home without incurring excessive energy costs.

Ready to optimize your home’s heating efficiency?
For professional HVAC maintenance, repairs, and expert advice, contact Bob’s Repair today and experience the comfort and peace of mind that comes from trusted service.

Stay warm, save energy, and let the experts handle your heating emergencies!