Emergency heat (often shown as "EM Heat" on your thermostat) turns off your heat pump's outdoor unit and heats your home with backup heat only, usually electric heat strips in the indoor air handler. It's meant for true emergencies, like an outdoor unit that's broken, buried in ice, or damaged. For everyday cold nights in Atlanta, leave your thermostat on regular "Heat" and let the system decide when it needs help. If you think your heat pump needs emergency heat to keep up, call The Air Company of GA 24 hours a day at 404-583-7788.
Emergency Heat vs. Auxiliary Heat: What's the Difference?
Most heat pump thermostats show two backup-heat messages, and they mean different things.
- Auxiliary heat ("Aux Heat") comes on automatically. Your heat pump keeps running, and the backup heat adds a boost when it's very cold outside, when you raise the thermostat several degrees at once, or while the outdoor unit runs a defrost cycle. It shuts off on its own once the house catches up.
- Emergency heat ("EM Heat") is something you switch on by hand. It locks out the heat pump completely and runs only the backup heat until you switch it back.
Seeing "Aux Heat" now and then on a cold Atlanta morning is normal. Seeing it constantly, or needing "EM Heat" to stay warm, usually means something is wrong with the heat pump.
When Should You Use Emergency Heat?
Use emergency heat only as a short-term fix while you wait for a repair. Good reasons include:
- The outdoor unit is completely iced over and stays that way after a defrost cycle.
- A tree limb, storm, or vehicle has damaged the outdoor unit.
- The outdoor fan isn't spinning, or the unit is making grinding or banging noises.
- The heat pump runs but blows cool air in heat mode and the house keeps getting colder.
If none of these apply, emergency heat isn't needed. Our winters in Atlanta, Sandy Springs, Marietta and Roswell are mild enough that a healthy heat pump handles most of the season by itself, with auxiliary heat covering the occasional hard freeze.
Why Emergency Heat Raises Your Power Bill
A heat pump moves heat from outside into your home, which takes far less electricity than making heat from scratch. Electric heat strips make heat directly, so running on emergency heat for days can cost noticeably more than normal heat pump operation, often two to three times as much for the same comfort. That's why emergency heat should be a bridge to a repair, not a way to get through winter.
If your home has a dual-fuel system (a heat pump paired with a gas furnace), emergency heat runs the furnace instead of heat strips. That costs less than heat strips, but the heat pump still isn't doing its job, so it's worth having it checked.
How to Switch Emergency Heat On and Off
- Set your thermostat's mode to "EM Heat" or "Emergency Heat." On many thermostats it's in the mode menu, next to Heat, Cool and Off.
- Set your temperature as usual. Raise it a couple of degrees at a time so the house doesn't overshoot.
- Call for service so the heat pump can be repaired.
- Once the repair is done, switch the mode back to regular "Heat."
If your thermostat screen is blank or won't change modes, see our guide on why a thermostat screen goes blank.
Signs Your Heat Pump Needs a Repair, Not Emergency Heat
- "Aux Heat" stays on for hours even in mild weather.
- Your electric bill jumps without a cold snap to explain it.
- The outdoor unit runs constantly or turns on and off too often.
- Ice builds up on the outdoor coil and doesn't clear.
- Some rooms stay cold while the system runs nonstop.
Common causes include low refrigerant, a failed defrost control, a bad outdoor fan motor, a dirty filter or coil, or thermostat wiring problems. Our NATE-certified technicians diagnose these on residential and commercial systems every day. Learn more about our heat pump service in Atlanta.
Keep Your Heat Pump Out of Emergency Mode
Most heat pump breakdowns start small. A yearly tune-up catches weak parts, dirty coils and low refrigerant before a cold night does. Our service plan is $159 per year for your first system and $60 for each additional unit, with priority scheduling for members. It's one of the best values in the city.
The Air Company of GA is a family-owned Bryant dealer at 10 Glenlake Parkway, Suite 130, Atlanta, GA 30328, open 24 hours. We serve Atlanta (including Buckhead, Midtown and Virginia Highland), Sandy Springs, Marietta, East Cobb, Smyrna, Vinings, Roswell, Alpharetta, Johns Creek, Duluth, Norcross, Peachtree Corners, Brookhaven, Dunwoody, Chamblee, Doraville, Tucker and Decatur. See our full service area, or call 404-583-7788 any time.
Emergency Heat FAQs
Is it bad to run emergency heat all the time?
It won't hurt the equipment, but it costs much more to run than your heat pump and it hides a problem that needs a repair. Use it only until a technician can fix the heat pump.
Why does my thermostat say "Aux Heat" on cold mornings?
Auxiliary heat comes on automatically when it's very cold outside, when you raise the temperature several degrees at once, or during a defrost cycle. Short periods of "Aux Heat" are normal. If it stays on for hours in mild weather, have the heat pump checked.
Should I switch to emergency heat when it's below freezing in Atlanta?
No. Leave the thermostat on regular "Heat." The system brings on auxiliary heat by itself when it needs help. Switching to emergency heat during a cold snap just shuts off the more efficient heat pump.
Why is my heat pump blowing cold air?
During a defrost cycle, a heat pump can briefly blow cooler air, which is normal. If it keeps blowing cool air in heat mode, it may be low on refrigerant or have a failed reversing valve or defrost control. Switch to emergency heat if the house is getting cold, and call for service.
Does a gas furnace have emergency heat?
No. Emergency heat is a heat pump setting. In a dual-fuel system, emergency heat runs the gas furnace instead of the heat pump.
Who can repair my heat pump at night or on the weekend?
The Air Company of GA is open 24 hours for residential and commercial heat pump repair across our service area. Call 404-583-7788.
