The emergency heat setting on your thermostat is a backup that runs when your heat pump cannot. It shuts off the heat pump and warms your home with electric backup strips instead. You use it only when the heat pump stops working, not because the weather turned cold.
Seeing that “EM Heat” label can feel alarming. It is not a warning light, and it does not mean something broke. It is simply a tool built into every heat pump system. Let us walk through what it does, when to use it, and when to leave it alone.
What Does Emergency Heat Mean on My Thermostat?
Emergency heat means your system is running on backup heat alone. Normally, your heat pump warms the house by pulling heat from the outside air. When you switch to emergency heat, the thermostat shuts the heat pump off. Then it heats your home with electric strips inside the air handler.
Those strips work like the coils in a toaster. They make heat directly from electricity. They are reliable, and they warm the house well. They just use a lot more power to do it.
One important note. Only homes with a heat pump have this setting. If you heat with a gas furnace or straight electric system, you will not see it. You also do not need it. Most Jacksonville homes run heat pumps, so odds are you have it.
Emergency Heat vs Auxiliary Heat: What Is the Difference?
These two get mixed up all the time, though they work very differently. The names sound alike, yet one is automatic and one is manual.
Auxiliary heat, or aux heat, is the automatic helper. On a cold day, your heat pump keeps running while the backup strips kick on to help. The two work as a team. You never push a button, since your system does it on its own.
Emergency heat is the manual override. When you switch to it, the heat pump shuts off completely. Only the backup strips run. You choose this setting yourself, and you should only choose it in a true emergency.
When Should I Use Emergency Heat?
Use emergency heat only when your heat pump has stopped working. That is the one real reason to flip it on. If your outdoor unit is frozen, dead, or blowing cold air, emergency heat keeps you warm until help comes.
Here is the mistake people make. They flip it on during a cold snap, thinking it warms the house faster or better. It does neither. It only raises your bill. Your heat pump handles our Jacksonville cold just fine on its own.
That matters even more here. Our cold snaps are short, often a night or two. Your heat pump is built to ride them out. To see how well these systems hold up, read whether heat pumps can handle Jacksonville freezes. For everyday winter chill, leave the thermostat on regular heat.
Does Running Emergency Heat Cost More?
Yes, and the difference can be steep. Emergency heat runs on electric resistance strips, which are far less efficient than the heat pump. The U.S. Department of Energy calls those backup elements inefficient and says to use them as little as possible.
In plain terms, your heat pump moves heat, while the strips make heat from scratch. Making heat takes far more electricity than moving it. Run emergency heat for days, and you will feel it on the bill.
So treat it as a short-term bridge. Flip it on to stay warm, then switch back to regular heat once your system is fixed. Leaving it on longer than you need is money out the window.
What If My Backup Heat Runs a Lot?
If your backup heat runs often, that can point to a problem. A healthy heat pump does most of the heating on its own in our mild winters. Heavy backup use can mean low refrigerant, a dirty coil, or a pump that is wearing out.
Watch for a few signs. The air from the vents feels cool, the system runs nonstop, or the bill jumps for no clear reason. Any of those is worth a look. A quick tune-up often finds the cause and gets your heat pump back to the heavy lifting.
My Heat Pump Stopped Heating. What Should I Do?
First, run a few quick checks before you assume the worst. A small fix can save you a service call.
- Make sure the thermostat is set to heat and a few degrees above the room.
- Check the breaker for the system and reset it if it tripped.
- Look at the air filter and replace it if it is clogged.
- Step outside and clear any ice or debris off the outdoor unit.
If none of that brings the heat back, switch to emergency heat to stay warm. Then call for repair. On a cold night, our 24/7 emergency service means you can reach a real person right away. Our Jacksonville heating team can find the problem and get your heat pump running again.
If your heat pump fails often or leans on backup heat a lot, it may be aging out. In that case, heat pump installation can save you more than repair after repair. A tune-up before winter also catches many of these problems early.
Common Questions About Emergency Heat
Why Did My Emergency Heat Turn On by Itself?
True emergency heat does not turn on by itself, since it is a manual setting you choose. If you see a backup-heat light, you are likely seeing auxiliary heat, which is normal on cold days. But if the thermostat truly sits on EM heat and no one touched it, something is off. That points to a thermostat fault or a wiring issue. It can also mean the heat pump already failed and the system fell back on backup. Either way, it is worth a quick look from a tech.
Will Running Emergency Heat Hurt My System?
No, running emergency heat will not damage your system. It is a built-in safety mode, designed for exactly this. The only real downside is the higher bill from the electric strips. So use it without worry when you need it, then switch back once the heat pump is fixed.
How Long Can I Run Emergency Heat?
Run it as long as you need to stay warm, but think in days, not weeks. It is a short bridge to get you through until a repair. Because the cost climbs each day, call for service quickly rather than riding it out. The sooner your heat pump is back, the sooner your bill drops.
We Are Here When Your Heat Pump Needs Help
A heat pump that quits on a cold night is stressful, especially with family at home. You should not have to guess your way through it. That worry is exactly what we are here for.
Our team lives and works right here in Northeast Florida. We fix heat pumps, explain your options in plain words, and get your home warm again. You will deal with real neighbors who treat your home like their own.
Call or text us anytime at (904) 982-9731, or reach out through our contact page. Tell us what your system is doing, and we will help you sort it out.