If you’ve ever glanced at your thermostat and seen “EM Heat,” you’ve probably wondered what it actually means. At C&R Services, we get that question a lot—especially when the weather suddenly turns cold. So, what is EM heat in the first place? In simple terms, it’s your system’s backup heating mode—something that kicks in when your heat pump can’t pull enough warmth from the air outside.
Now, that backup feature can be a lifesaver on a freezing morning, but it also uses more electricity than normal heating. Let’s go over how it works, when to use it, and how to keep it from driving up your energy bill.
What Is EM Heat on a Thermostat?
The term EM heat stands for emergency heat. It’s a backup heating mode on a heat pump system. When outdoor temperatures get too low or the main heat pump can’t operate efficiently, your thermostat can switch to emergency heat—usually powered by electric resistance coils or a gas furnace backup.
So, what is emergency heat exactly? It’s the system’s way of saying, “Your heat pump needs help right now.” Instead of transferring warmth from outside air, emergency heat generates its own heat. That’s why it uses more energy and runs up higher electric bills.
(Quick tip from the field—many homeowners accidentally turn on emergency heat manually, thinking it’ll heat their home faster. It will, but you’ll pay for it later when the power bill arrives.)
How Emergency Heat Works
When your heat pump can’t pull enough warmth from the air, the backup heating source steps in automatically. For most systems, this is electric resistance heating inside the air handler.
Step 1: Heat Pump Struggles in Extreme Cold
Heat pumps are efficient, but they rely on outdoor air for warmth. Once the air gets too cold, the system needs help.
Step 2: EM Heat Activates
At this point, emergency heat turns on to keep your indoor temperature stable. Your thermostat might display “AUX” or “EM Heat” to indicate the switch.
If you’ve ever wondered how your system transitions between cooling and heating in the first place, check out our related article on how to switch your AC to heat. It’s a quick, step-by-step guide that explains thermostat modes and helps you avoid common seasonal mix-ups.
Step 3: Higher Power Consumption
Because resistance heating doesn’t transfer heat—it creates it—it’s much less efficient. During normal operation, your heat pump moves heat from outdoors into your home, which the U.S. Department of Energy notes is far more energy-efficient than generating heat directly. When EM heat turns on, however, the system switches to that less efficient electric resistance mode, which is why energy use climbs quickly.
When Should You Use EM Heat?
There are two main scenarios when it’s appropriate to switch to EM heat manually:
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Your outdoor unit isn’t working.
If the heat pump freezes over, trips a breaker, or stops running altogether, emergency heat will keep your home warm until repairs are made. -
Your system can’t defrost itself.
Sometimes, the outdoor coil ices up in extreme conditions. Switching to emergency heat can prevent further freezing while you call for service.
Otherwise, let your thermostat handle it automatically. Most modern systems will engage auxiliary or emergency heat on their own when needed.
(From experience—if your emergency heat runs constantly for days, something’s off. It might be a sensor, refrigerant charge, or airflow issue.)
Why EM Heat Shouldn’t Run All the Time
It’s tempting to think “more heat = better comfort,” but EM heat is only meant for short-term use. It’s like driving your car in first gear all week—technically possible, but inefficient and stressful on the system.
If you find emergency heat staying on for long stretches, have your system checked. At C&R Services, we often find simple causes: a dirty filter, blocked outdoor coil, or faulty thermostat setting. Fixing these can save hundreds of dollars in wasted energy.
For added protection, the U.S. Department of Energy recommends scheduling seasonal maintenance to keep your heat pump and backup systems balanced and efficient.
Troubleshooting: What To Do If EM Heat Turns On Unexpectedly
Step 1: Check Thermostat Settings
Make sure it’s not accidentally set to emergency heat manually.
Step 2: Inspect Airflow
Replace dirty filters and clear vents. Restricted airflow makes your system work harder than necessary.
Step 3: Call a Technician
If EM heat keeps coming on without extreme weather, something inside the system needs attention. That’s where we come in.
At C&R Services, our licensed technicians can test sensors, defrost cycles, and backup heating elements to ensure your system operates safely and efficiently.
When to Call for Help
If your heat pump is stuck in EM heat mode, or you’re unsure when to use it, don’t wait until the next cold front. Proper troubleshooting keeps your home comfortable and prevents costly wear on your system.
Reach out to C&R Services—we handle heat pump services such as diagnostics, repair, and maintenance with precision and honesty.
Final Thoughts
So, what is EM heat? It’s your heat pump’s emergency backup for extreme conditions or system failures. While it’s there for safety and comfort, it’s not meant for everyday heating. Use it sparingly, and schedule regular maintenance to avoid relying on it too often.
If you think your system is running on emergency heat more than it should, contact C&R Services today for expert inspection and support. We’re proud to serve homeowners across East Texas—keeping comfort steady through every season.
Call us today at (903) 204-7571 to schedule your heat pump service or maintenance.
FAQs
Here are a few quick answers to the most common questions we get about EM heat and how to use it properly.
EM Heat stands for Emergency Heat, the backup mode your system uses when the heat pump can’t keep up. It’s typically powered by electric or gas heat.
Yes. EM Heat should only run when necessary. If it stays on constantly, it’s a sign your heat pump needs maintenance or repair.
Absolutely. EM Heat uses far more electricity than standard heat pump operation. Limiting its use saves energy and reduces utility bills. What Does EM Heat Mean on My Thermostat?
Is It Bad If EM Heat Is Always On?
Does EM Heat Cost More to Run?
