When Should You Use Emergency Heat on a Heat Pump?

Many homeowners feel unsure when they see the emergency heat setting on their thermostat. A heat pump normally works by transferring heat from outdoor air into your home, even during cold weather. However, emergency heat mode often creates confusion because people assume it should be used whenever temperatures drop. In reality, it serves a specific purpose. This article explains when to use emergency heat correctly, helping you maintain comfort, avoid high energy costs, and protect your heating system.

How a Heat Pump Normally Works

A heat pump heats your home by moving heat rather than creating it. First, the outdoor unit absorbs heat from the air using refrigerant, then the system transfers that heat indoors through the compressor cycle. Even in cold weather, this process remains efficient. Occasionally, frost may form on the outdoor coil, so the system enters defrost mode to remove ice. Meanwhile, auxiliary heat automatically activates only when extra warmth is needed, ensuring steady indoor comfort without manual intervention.

What Emergency Heat Mode Actually Means

Emergency heat mode is a backup heating setting designed for situations when the main heat pump cannot operate properly. When activated, it shuts off the outdoor unit and relies entirely on a secondary heat source to warm your home. Unlike auxiliary heat, which turns on automatically to assist the system, emergency heat is a manual choice used only during system problems or damage. Typically, this backup comes from electric resistance coils or a furnace, providing reliable heat during temporary equipment failures.

When to Use the Emergency Heat on a Heat Pump

• Outdoor Unit Failure: Switch to emergency heat if the outdoor heat pump stops working, shuts down, or shows signs of a malfunctioning heat pump. This setting bypasses the heat pump and keeps your home warm using the backup heating source, which may be electric resistance heat or a gas furnace in dual-fuel systems.
  
• Ice Damage or Mechanical Issues: If heavy ice covers the outdoor unit or the heat pump is damaged, the system may not extract enough heat from outside air. In this case, activating EM heat protects the equipment until heat pump repair is completed.
  
• Severe Weather Conditions: During extreme cold, a heat pump may run longer to maintain indoor comfort, but it should still operate normally. Emergency heat should only be used if the system is malfunctioning, damaged, or unable to produce warm air, not simply because outdoor temperatures are low.
  
• Temporary Safety Situations: If you hear unusual noises, notice poor heating performance, or suspect system failure, switching to emergency heat mode ensures proper heat while waiting for professional service.
  

When You Should NOT Use Emergency Heat

You should not activate emergency heat during normal cold weather or mild freezing temperatures because a regular heat pump is designed to draw heat from the outside air efficiently. In most cases, auxiliary heat (aux heat) automatically supports the system when extra warmth is needed, so using emergency heat mode is unnecessary. Misusing emergency heat disables the heat pump and relies on electric heat strips, which are less efficient than your heat pump. Therefore, avoid prolonged use unless your heat pump isn’t functioning or a true heating emergency occurs.

Signs Your System May Need Emergency Heat

• Strange Noises: Grinding, buzzing, or rattling sounds from the outdoor unit may indicate mechanical damage or compressor problems. In such cases, switching to emergency heat can prevent further strain.
  
• No Warm Air: If your vents blow cool or lukewarm air while the thermostat is set to heat, the heat pump may not be generating enough warmth, signaling a possible system issue.
  
• Outdoor Unit Not Running: When the outdoor unit remains completely off during a heating call, the system may have an electrical or component failure requiring backup heat.
  
• Error Codes or System Shutdown: Modern thermostats may display warnings or shut down the system for protection. Activating emergency heat temporarily helps maintain indoor comfort until professional repair.
  

Energy Efficiency and Cost Impacts

Emergency heat uses more electricity because the system bypasses the heat pump and generates heat directly instead of transferring it. A regular heat pump operates efficiently by moving heat, while EM heat relies on energy-intensive backup heating elements. Therefore, turning on your emergency heat significantly increases energy consumption compared to normal heat pump operation. Utility bills may rise quickly with prolonged use, especially during frequent heating cycles. For this reason, emergency heat should remain a short-term solution only when the heat pump needs repair or cannot function properly.

How to Turn On Emergency Heat Safely

To activate emergency heat, switch your thermostat from normal heat mode to the “EM Heat” or emergency setting. This step disables the outdoor unit and starts the backup heating source. However, ensure there are no visible electrical issues or unusual odors before turning it on. After activation, monitor indoor temperature and airflow closely. If heating performance seems abnormal, contact a qualified technician promptly to prevent further system damage.

Professional Maintenance and Prevention Tips

Regular maintenance keeps your HVAC system reliable and reduces the need for emergency heat activation. Schedule seasonal inspections so your heat pump functions efficiently during cold weather. In addition, replace filters regularly to maintain airflow and proper heat transfer. Keep the outdoor unit clean and free from debris or ice buildup to prevent heat pump failure. Professional service from Maine Energy Experts helps ensure accurate diagnostics, safe operation, and long-term system performance, reducing the risk of unexpected heating problems.

Conclusion

In conclusion, understanding how emergency heat works helps you use your heat pump systems more efficiently and avoid unnecessary costs. The emergency heat function is not the same thing as auxiliary heat, and it should only be used when your heat pump can’t function or during system failure. Knowing when to switch your thermostat to emergency heat keeps your heat pump running safely, ensures proper comfort, and protects your equipment during extreme cold or unexpected heating problems.