If you’ve ever glanced at your thermostat during a freezing winter night and seen a mysterious button labeled “EM heat,” you’re not alone. Many homeowners are left wondering, “What is EM heat?” “What does EM heat mean?” or “What is EM heat on my thermostat?“
Short for Emergency Heat, EM heat, or auxiliary heat, is a backup heating option used in homes that rely on a heat pump system. When the heat pump can’t keep up with demand—either due to extremely cold temperatures or mechanical failure—your thermostat can switch to EM heat to activate a secondary heat source (usually electric resistance heating or a gas furnace).
But here’s the catch: while EM heat can save the day in a pinch, it’s not designed for long-term use. It’s more expensive and less efficient than your regular heat pump setup, and knowing when and how to use it can save you hundreds on your energy bill.
What Is EM Heat on My Thermostat?
EM heat, or emergency heat, is a backup heat setting on your thermostat. It is most commonly found in homes that use a heat pump system. Instead of pulling heat from the outdoor air like your normal heat pump does, EM heat uses a secondary heat source to warm your home.
That backup heat source may be electric heat strips, a gas furnace, an oil burner, or another form of emergency heating. The main thing to know is that EM heat is not meant to be your everyday heating setting. It is there to help when your regular heat pump is having trouble keeping your home warm.
EM Heat vs Heat: The Important Difference
So how exactly does EM heat vs heat break down? Let’s explore both heating systems so you can make the best decision for your home.
1. The Basics
- Heat (Standard Mode): In a heat pump system, “Heat” uses the pump to extract warmth from the outside air—even in colder weather—and deliver it indoors. It’s efficient and cost-effective, using electricity in a smart, energy-saving way.
- EM Heat (Emergency Heat): Bypasses the heat pump entirely and turns on a backup heat source. This could be an electric heat strip, oil burner, or gas furnace. It’s designed to be used when your main heat pump isn’t functioning properly or when outside temperatures are too cold for the pump to work efficiently.
2. Which One Is Better?
It depends on the situation.
- Standard Heat Mode is almost always the better choice for daily heating needs. It’s cheaper and designed for regular use.
- EM Heat is ideal only when your heat pump has failed or during freezing weather when the pump can’t keep up. If your thermostat automatically switches to EM Heat without manual input, you should consider calling a technician.
3. Pros and Cons of EM Heat on Thermostat
| Feature | Standard Heat | EM Heat |
| Cost Efficiency | Highly efficient | Expensive to operate |
| Usage Frequency | Daily use | Emergency/backup only |
| Temperature Range | Works well above 30°F | Effective in extreme cold |
| Automatic Switch | Normal function | May need manual activation |
How to Know If You Need EM Heat
Use this quick checklist to know when EM Heat might be appropriate:
- The outdoor temperature is below 30°F and your home is still cold.
- Your heat pump is making unusual noises or not blowing warm air.
- A technician has advised using EM Heat while awaiting repairs.
If none of these apply, stick with your standard heat mode for better efficiency and lower bills.
When Should You Use EM Heat?
You should only use EM heat when your heat pump is not working correctly or when a technician tells you to turn it on while you wait for repairs. EM heat can also be helpful during very cold weather if your heat pump cannot keep up and your home is still cold.
You may need EM heat if:
- Your heat pump is not blowing warm air.
- Your home feels cold even though the heat is on.
- Your outdoor unit is frozen or not running.
- Your thermostat switches to EM heat on its own.
- An HVAC technician has told you to use it temporarily.
If your system is working normally, standard heat is usually the better choice. It is more efficient and is designed for everyday use.
When Should You Turn EM Heat Off?
EM heat should be turned off once your heat pump is working normally again. Leaving it on for too long can increase your energy bill because backup heat often uses more power than the regular heat pump setting.
You should turn EM heat off if:
- Your heat pump has been repaired.
- Your home is warming normally again.
- The outdoor temperature is no longer extremely low.
- You turned it on by mistake.
- You are using it as your main heat source every day.
If your thermostat keeps switching to EM heat or your home still feels cold, it may be time to have your system checked. A technician can inspect the heat pump, thermostat, and backup heat source to make sure everything is working the way it should.
Common FAQs: Answered
Q: Should I leave EM Heat on thermostat all winter?
A: No. EM Heat is a temporary fix and is much more expensive to operate than your regular heat pump. If your system keeps switching to EM Heat, it’s likely a sign something’s wrong.
Q: Why is my EM Heat on, but the house is still cold?
A: Your backup heating system might not be working correctly. Check the thermostat settings and call a professional to inspect the unit.
Q: Does EM Heat mean my heat pump is broken?
A: Not necessarily. Some systems may switch to EM Heat during extremely low outdoor temperatures. However, if it switches often or without a clear temperature drop, get it checked out.
Q: Can I manually turn on EM Heat?
A: Yes, most thermostats let you manually activate EM Heat. Only do this if your heat pump isn’t working or your technician has recommended it.
Triad Mechanical Has the Resources You Need
At Triad Mechanical, we understand that heating your home is about more than comfort—it’s about safety, efficiency, and peace of mind. Whether you’re trying to figure out what EM heat means on your thermostat or experiencing a sudden heating failure, our team is equipped to help.
From diagnosing tricky heat pump issues to installing energy-efficient backup systems, we provide expert heating services tailored to your home’s needs. Don’t let winter catch you off guard—our 24/7 emergency services and expert technicians are ready when you need us most. Need help? Call Triad Mechanical, your local experts in all things EM heat on the thermostat.