What Does EM Heat Mean?

You walk to your thermostat on a cold winter morning and notice an orange button. The button says EM HEAT or EMH and you have never pressed it before. You are not sure what it does or if you should be worried. This guide will explain exactly what that button means in plain language.

How A Heat Pump Heats Your Home

Pulling Heat From Outside Air

A heat pump works in a very clever way to warm your house. It does not burn gas or create heat the way a furnace does. It pulls heat energy from the cold outside air and moves it indoors. This process works well even when the temperature outside is quite cold. The Energy.gov Heat Pump Guide explains that modern heat pumps can pull heat from air as cold as zero degrees Fahrenheit. The outdoor metal unit runs constantly in cold weather to keep your home warm.

When The Outdoor Unit Struggles

The outdoor unit has limits on how well it can work in extreme cold. When temperatures drop very low, the unit cannot pull enough heat from the outside air on its own. The machine has to work harder and harder to keep your home at the right temperature. This is exactly why your thermostat has a backup heating option built into it. That backup option is what the EM or EMH button controls. Understanding this process helps you know when and why to use that orange button.

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What The EM Heat Button Actually Does

Electric Backup Heating Strips

The EM HEAT setting turns off your outdoor heat pump unit completely. It switches your heating system over to a set of electric resistance coils called heat strips. These metal coils sit inside the air handler unit in your attic or closet. They work the same way that the coils inside a toaster oven work. Electricity runs through the metal strips and the strips get extremely hot. Your indoor fan blows air across the hot strips and pushes warm air through your house. This system heats your home reliably no matter how cold it gets outside.

What EM Heat Means On Your Thermostat

What does em heat mean when you see it displayed on the screen? It means your system has switched from the efficient heat pump mode to the backup electric heat mode. The outdoor unit shuts down entirely when this setting is active. Only the indoor air handler and the electric strips are doing any work. Some thermostats use the label EMH instead of EM HEAT but both labels mean the same thing. The button is short for emergency heat and it was designed for specific situations only.

The Difference Between EM Heat And Regular Heat

The heat vs em heat question confuses many homeowners every winter. Regular heat mode uses the outdoor heat pump unit as the primary source of warmth. The heat pump is very efficient and uses less electricity than the backup strips. EM heat mode bypasses the outdoor unit entirely and runs only the indoor electric strips. The strips are much less efficient than the heat pump and they use a lot more electricity. Your electric bill will climb noticeably if you leave em heat mode running for many days in a row.

Heat Pump Repair And Replacement Costs

System Component	Main Purpose	Expected Lifespan	Estimated Part Cost	Estimated Labor Cost
Electric Heat Strips	Provides EM Heat backup warmth	Ten to fifteen years	$100 to $250	$200 to $350
Reversing Valve	Switches heat pump between modes	Ten to twenty years	$200 to $400	$300 to $500
Defrost Control Board	Manages ice removal on outdoor unit	Eight to twelve years	$100 to $200	$150 to $250
Dual Run Capacitor	Starts compressor and outdoor fan	Five to ten years	$20 to $40	$150 to $200
Thermostat Replacement	Controls all heating and cooling modes	Ten to fifteen years	$50 to $250	$100 to $200

You can review current labor rates in your area on HomeAdvisor Heat Pump Repair Costs before calling a technician. Knowing the fair price range helps you make a confident decision when getting a quote.

When To Switch To EM Heat

Your Outdoor Unit Is Broken

The right time to use em heat on a heat pump is when your outdoor unit has stopped working. If the outdoor fan is not spinning at all, the unit has a mechanical problem. If you hear a loud grinding or banging noise coming from the outdoor box, something is wrong inside it. Switching to em heat keeps your home warm while you wait for a repair technician to arrive. You should not leave the broken outdoor unit running because it can cause more damage. Pressing the em heat button protects the machine while it waits for service.

Your Outdoor Unit Is Frozen Solid

A heat pump can freeze up during very cold and wet weather. A small amount of frost on the outdoor fins is completely normal and the machine defrosts itself automatically. A thick coating of ice covering the entire unit is a serious problem. The machine cannot pull heat from the air when it is buried under a solid layer of ice. You should switch to em heat if the outdoor unit looks completely frozen and the ice does not melt away within an hour or two. A thermostat clicks but no heat situation often happens when the outdoor unit has frozen and the system cannot complete a full heating cycle.

Signs Your Heat Pump Needs A Technician

You need professional help if you notice any of the following warning signs on your system.

• Your outdoor unit is completely silent and the fan blades are not moving at all.
• The outdoor unit is encased in a thick layer of ice that has not melted after two hours.
• Your home feels much colder than your thermostat setting even after running for an hour.
• You hear loud banging, grinding, or screeching noises coming from the outdoor metal box.
• Your indoor AC fan not turning on means the air handler may have lost power.

Keeping Your Heat Pump Working Well

Changing Your Filter Every Month

A clean filter helps your heat pump work efficiently in cold weather. A dirty and clogged filter forces the indoor fan to work much harder than it should. This puts extra stress on the motor and the electric strips inside the air handler. You should check and replace your indoor paper filter at least once a month during the heating season. Reviewing the EPA Indoor Air Quality guidance shows that clean filters also protect the air your family breathes every day. A clean system is less likely to fail and force you into em heat mode unexpectedly.

Keeping The Outdoor Unit Clear

You should check the area around your outdoor unit every week during winter storms. Remove any snow that has piled up on top of the flat metal lid of the unit. Knock off any large ice chunks that have formed on the sides of the machine. Make sure nothing is blocking the sides of the unit where air flows in and out. The machine needs clear space all around it to pull heat from the outside air. A blocked unit will freeze up faster and may fail completely on the coldest nights of the year.

FAQ

What does em heat mean on my thermostat?

EM heat stands for emergency heat and it is a backup heating mode built into every heat pump system. When you press the EM HEAT button, your thermostat turns off the outdoor heat pump unit and switches all heating over to the electric resistance strips inside your indoor air handler. These strips create heat by running electricity through metal coils, similar to how a space heater works. This mode was designed as a temporary solution for when the outdoor unit breaks down or freezes over in winter. It keeps your home warm while the outdoor unit is repaired or while a technician is on the way.

What is the difference between heat and em heat on a heat pump?

Regular heat mode uses the outdoor heat pump as the primary source of warmth, which is very energy efficient. Em heat mode shuts down the outdoor unit completely and relies only on the indoor electric resistance strips. Heat pumps are efficient because they move heat rather than create it, making them two to three times less expensive to run than electric strips. The em heat mode creates heat directly from electricity, which consumes significantly more power. Most homeowners notice a higher electric bill within just a few days of running em heat continuously.

Does em heat cost more money to run than regular heat?

Yes, em heat costs noticeably more to run than the standard heat pump mode. Electric resistance heating strips are much less efficient than the heat pump process of moving heat from outside air. A heat pump can produce two to three units of heat energy for every one unit of electricity it uses. An electric resistance strip produces only one unit of heat for every one unit of electricity it uses. The difference in your monthly electric bill can be significant if em heat runs for many days in a row. You should switch back to regular heat mode as soon as your outdoor unit is repaired and working again.

When should I switch to emergency heat on my heat pump?

You should switch to emergency heat only when your outdoor unit has stopped working or is frozen solid with a thick coat of ice. The em heat setting is not meant to be used as a regular heating mode during cold weather. If your outdoor unit is running normally, you should leave the thermostat set to regular heat mode and let the efficient heat pump do its job. The only other time to consider em heat is if a technician instructs you to use it while waiting for a specific part to arrive. Running em heat unnecessarily will increase your electric bill without providing any benefit to your system.

Will leaving em heat on damage my heat pump over time?

Leaving em heat on will not directly damage the indoor electric strips because they are designed to handle continuous operation. However, leaving the outdoor unit off for a long period when it actually works fine means you are missing the most efficient way to heat your home. The outdoor unit itself will not suffer from being switched off, and it will be ready to run again as soon as you turn em heat off. The real risk is simply the extra cost of running the less efficient electric strips for days or weeks at a time. Our HVAC Services team can inspect your system and tell you if your outdoor unit is safe to run or if it needs repair before you turn it back on.

Conclusion

The EM HEAT button on your thermostat is a helpful tool for a very specific situation. You should use it only when your outdoor heat pump unit has broken down or frozen over completely. Switch back to regular heat mode as soon as the outdoor unit is working again to keep your electric bills reasonable. Call our expert team right now if your heat pump is struggling to keep your home warm this winter. Visit our Contact Us page to schedule a fast inspection today.