Knowing when to use emergency heat on heat pump can prevent costly damage and keep your home comfortable when your main heating source isn’t working. Many homeowners aren’t sure when this option is necessary or how it affects their system. Understanding how and when to activate this setting can protect your HVAC equipment and help you avoid sky-high energy bills.
In this blog you’ll learn:
- What emergency heat actually does
- When it’s okay to use it (and when it’s not)
- What to do if your system keeps defaulting to it
We’re proud to serve homeowners in Forest Acres, SC, and surrounding areas with full-service HVAC repairs, heat pump diagnostics, and more.
What Is Emergency Heat on a Heat Pump?
Emergency heat is a secondary heating option that bypasses your heat pump’s outdoor unit and relies solely on your backup heating source, usually electric resistance coils or a gas furnace. It’s designed for short-term use when your main heat pump system fails or needs servicing.
Unlike auxiliary heat, which activates automatically when extra heating is needed, emergency heat must be manually turned on at the thermostat. This setting prevents the heat pump from running entirely, signaling that you’re intentionally relying on the backup system.
5 Times to Use Emergency Heat on Heat Pump Systems
While it may sound like a convenient fix, emergency heat is expensive to run and shouldn’t be used unless absolutely necessary. Here are five situations where it’s appropriate:
1. Your outdoor unit is damaged or not running
If your outdoor heat pump isn’t functioning due to damage, ice buildup, or a mechanical issue, it won’t be able to extract heat from the air. Switching to emergency heat ensures your home stays warm while you wait for service.
- Common causes: Frozen coils, compressor failure, or blown fuses
- First step: Visually inspect the outdoor unit for damage or obstruction
- Call a pro: Don’t run the system in this condition without expert help
2. You’ve scheduled a heat pump repair
If your technician has diagnosed an issue with your heat pump and ordered parts, you may be advised to use emergency heat temporarily until repairs are complete.
- Follow instructions: Use this mode only as directed
- Monitor closely: Keep an eye on energy usage during this time
- Keep vents clear: Ensure airflow remains unobstructed for electric or gas backup
3. Extremely cold temperatures hit your area
Heat pumps are most efficient in moderate climates. When outdoor temperatures drop below 30°F, some systems struggle to extract enough warmth from the air.
- Temporary use: Activate emergency heat only during the coldest days
- Energy tip: Switch back once temperatures rise above freezing
- Upgrade option: Newer cold-climate heat pumps may reduce the need for this
4. The system enters emergency heat on its own
Some thermostats automatically activate emergency mode if they detect that the heat pump has failed or isn’t responding.
- Don’t ignore it: This likely means there’s a fault in your main system
- Check settings: Verify it wasn’t switched manually
- Schedule service: A technician should inspect the system before resuming normal operation
5. You need heat immediately and can’t wait for repair
In rare cases, such as a system failure during extreme cold or while waiting for an emergency HVAC visit, you may need to use emergency heat just to keep your home safe.
- Use sparingly: Try to limit usage to a few hours
- Safety first: Protect family members from freezing temperatures
- Plan a fix: Use this time to arrange professional service ASAP
Emergency Heat vs. Auxiliary Heat
Auxiliary heat turns on automatically when extra warmth is needed. Emergency heat is manually activated and should only be used when your heat pump can’t operate.
How to Tell If Emergency Heat Is Running
Depending on your system and thermostat, emergency heat may be labeled “EM HEAT,” “EMER,” or similar. Here’s how to confirm whether it’s active:
- The thermostat screen will show “EM HEAT” or a red indicator
- You won’t hear the outdoor unit running
- Your electricity usage may spike noticeably
- Vents may blow warmer air than usual, but recovery times can be slower
If you’re unsure, check your system manual or contact your HVAC technician for guidance.
Is It Bad to Leave Emergency Heat On?
Yes, emergency heat is not meant for long-term use. It uses significantly more energy than your heat pump and can lead to extremely high utility bills if left on for days at a time.
Emergency mode also bypasses your system’s normal safety and efficiency controls, which can lead to overheating or wear on internal parts if misused.
How to Fix a System Stuck on Emergency Heat
If your system keeps defaulting to emergency heat or won’t switch back to standard heating, here are some steps to take:
Check the thermostat settings
Sometimes, the setting was changed manually and just needs to be turned off.
- Action: Switch from “EM HEAT” back to “HEAT”
- Note: Wait 5–10 minutes to see if the outdoor unit turns on
Inspect the outdoor unit
If it’s covered in ice, debris, or appears inactive, there could be a system fault preventing normal operation.
- Look for: Icy coils, fan not spinning, loud humming
- Try this: Turn off the system for 10 minutes and restart
Call a professional HVAC technician
If nothing changes or emergency heat reactivates shortly after, it’s time for a full inspection.
- Testing required: Professionals check refrigerant levels, reversing valves, defrost cycles, and more
- Avoid delays: The longer the system runs in emergency mode, the higher your energy bills
Palmetto Air Conditioning Fixes Emergency Heat Problems Fast
If your system is stuck in emergency mode or you’re unsure when to use emergency heat on heat pump equipment, Palmetto Air Conditioning is here to help. We work with homeowners in Forest Acres, SC, to diagnose heat pump issues, restore efficient heating, and prevent unnecessary energy use. From frozen coils to faulty thermostats, our trained technicians can pinpoint the issue and get your system back to normal. Contact us today for reliable repair, expert guidance, and fast response when your system needs it most.
