Don't Panic! How and When to Use Your Emergency Heat

When to Use Emergency Heat: What Every Homeowner Should Know

Running emergency heat is a backup heating mode on your heat pump system that should only be activated during true emergencies—like when your outdoor unit is damaged, frozen solid, or completely non-functional. It bypasses your heat pump entirely and uses electric resistance heating, which can cost up to 6 times more than normal operation.

Quick Answer: When to Use Emergency Heat

• YES - Use It When: Your heat pump is broken, damaged, or frozen solid and won't heat your home
• YES - Use It When: An HVAC technician tells you to switch to it while awaiting repair
• NO - Don't Use It When: It's just very cold outside (that's what auxiliary heat is for)
• NO - Don't Use It When: You want to heat your home faster (this is a costly myth)
• NO - Don't Use It When: Your system is working normally

If you've ever noticed that red "EM Heat" light glowing on your thermostat and wondered what it means—or worse, if you've already switched to emergency heat and watched your electricity bill skyrocket—you're not alone. Many homeowners in Wakulla, Leon, and Franklin Counties misunderstand this feature, using it when they shouldn't or panicking when they actually need it.

Emergency heat is genuinely useful when your heat pump fails during cold weather, but it's also expensive and meant as a temporary solution only. Understanding the difference between emergency heat, auxiliary heat, and normal heat pump operation can save you hundreds of dollars and unnecessary stress.

Whether you're dealing with a struggling heat pump or just want to be prepared before winter arrives, knowing how and when to use emergency heat is essential for every homeowner. For comprehensive information on heat pump maintenance and service, check out our heat pump repair guide. If you're experiencing heating issues right now, contact us at Keith Key Heating & Air.

What Is Emergency Heat and How Does It Work?

To truly understand emergency heat, we first need to grasp how your heat pump normally works. Think of a heat pump as a smart, energy-efficient device that doesn't create heat but rather moves it. In the colder months, it extracts heat energy from the outside air, even when temperatures are low, and transfers it inside your home. This process is incredibly efficient because it's simply moving existing heat, much like a refrigerator in reverse. In fact, heat pumps can be more than 100% efficient, meaning they deliver more heat energy than the electrical energy they consume. They are especially efficient in milder climates, like ours in Wakulla, Leon, and Franklin Counties, typically performing optimally when temperatures are above 20 degrees Fahrenheit.

Now, let's talk about running emergency heat. Emergency heat is your heat pump system's backup heating source. It’s designed for those rare occasions when your primary heat pump system isn't able to do its job. Mechanically, when you switch your thermostat to "EM Heat," your outdoor heat pump unit is bypassed entirely. Instead, your indoor unit — specifically, electric resistance coils (often called heat strips) — takes over. These coils work much like the heating elements in a toaster or a hairdryer: an electric current runs through them, generating heat directly.

While simple and effective at producing warmth quickly, this method is far less efficient than a heat pump. Electric resistance heaters are considered 100% efficient because every unit of energy consumed equals one unit of heat produced. However, because heat pumps move heat rather than generate it, they are inherently more energy-efficient than electric resistance heating. This difference in efficiency is crucial when we consider the cost of operation, which we'll dive into shortly.

The Key Difference: Auxiliary Heat (AUX) vs. Emergency Heat (EM Heat)

This is where many homeowners get confused, and it’s important to clarify. Your heat pump system actually has two backup heating modes: Auxiliary Heat (AUX) and Emergency Heat (EM Heat). While both use electric resistance heating, their purpose and activation are very different.

• Auxiliary Heat (AUX): The Automatic HelperAuxiliary heat is an automated function designed to supplement your working heat pump. It kicks in automatically under specific circumstances to give your heat pump a boost. This usually happens when:
  • It's very cold outside: When outdoor temperatures drop significantly (often below 30-35 degrees Fahrenheit), your heat pump might struggle to extract enough heat from the air to keep your home comfortable. Auxiliary heat engages to help your heat pump reach the desired temperature.
  • Your thermostat setting is adjusted significantly higher: If you suddenly raise your thermostat by several degrees, your system might engage auxiliary heat to quickly catch up to the new setting.
  • During a defrost cycle: Heat pumps periodically go into a defrost mode to melt ice buildup on the outdoor coils (more on this later!). During this brief cycle, the auxiliary heat will activate to ensure warm air continues to circulate inside your home, preventing a cold draft.
  The key here is that auxiliary heat works with your heat pump. Your thermostat usually displays an "AUX" light when it's active, indicating that your system is working harder to keep you warm.
• Emergency Heat (EM Heat): The Manual OverrideEmergency heat, on the other hand, is a manual override. When you switch your thermostat to "EM Heat," you are telling your system to completely shut down the outdoor heat pump unit and rely solely on the electric resistance coils inside. This mode should only be used in true emergencies when your heat pump is malfunctioning or completely non-functional. The "EM Heat" light on your thermostat is a red flag, indicating that your system is operating in its most expensive mode. If this light is on, your heat pump compressor is not running, and all the heating is coming from those energy-hungry electric strips.

Understanding this distinction is vital. Auxiliary heat is a normal, automated part of your heat pump's operation in cold weather, designed to maintain comfort and efficiency. Emergency heat is a manual, last-resort option for when your heat pump is broken.

When Should You Be Running Emergency Heat?

Let's get straight to the point: running emergency heat should be a rare occurrence. It's not a convenience feature, nor is it meant for everyday use during a cold snap. It is a temporary solution, a bridge to keep your home warm when your primary heating system has failed, buying you time until professional repairs can be made.

The ONLY Times for Running Emergency Heat

We strongly advise activating emergency heat only in these specific, urgent situations:

• Heat Pump Malfunction or Failure: This is the most common and appropriate reason to use emergency heat. If your heat pump is damaged, blowing cold air, making unusual loud grinding noises, or simply not turning on, it's time to switch to EM Heat. Examples include:
  • Your outdoor unit was physically damaged (e.g., a fallen tree branch, an accident).
  • Your heat pump is running continuously but not warming your home.
  • The unit is completely frozen over and not responding to its normal defrost cycle (more on this below).
  • You notice a strong electrical burning smell coming from your unit, which indicates a serious problem (turn it off immediately and then consider EM heat if safe).
  • You hear strange, loud noises from the outdoor unit that are not part of a normal defrost cycle.
• Severe Icing of the Outdoor Unit: While heat pumps have a normal defrost cycle, sometimes extreme conditions or a system malfunction can lead to your outdoor unit becoming a literal block of ice. If your heat pump is caked in ice that doesn't melt after a few hours or during normal defrost cycles, and it's severely impacting performance, you might need to use emergency heat. In some rare cases, during freezing rain, manually switching to emergency heat can even protect the compressor fan from damage by stopping its rotation.
• Professional Advice: An HVAC technician has diagnosed a problem with your heat pump and instructs you to use emergency heat while you await a repair or replacement part. We will always guide you on the best course of action for your specific situation.

Signs Your Heat Pump May Be Malfunctioning and Requires Emergency Heat:

• Your heat pump is running, but only blowing cold or lukewarm air.
• The outdoor unit is completely iced over and doesn't defrost naturally.
• Your heat pump isn't turning on at all.
• You hear loud, unfamiliar noises (grinding, banging, screeching) coming from the unit.
• The "EM Heat" light is on, but you didn't manually activate it (this is a clear indicator of a fault).
• Your home won't reach the set temperature, even when outdoor temperatures are mild.

Common Misconceptions: When NOT to Use It

Unfortunately, many homeowners use emergency heat for the wrong reasons, leading to shockingly high utility bills. Let's clear up some common myths:

• Myth 1: "It's just too cold for my heat pump."We hear this often, especially during a severe cold snap in Wakulla, Leon, and Franklin Counties. Many assume that when temperatures drop, their heat pump simply "can't keep up," and they should switch to emergency heat. This is incorrect! Your system is designed to handle cold weather. When it's very cold, your heat pump will automatically engage its auxiliary heat to supplement its operation. That's what auxiliary heat is for – to help your heat pump perform efficiently in colder conditions, without completely shutting down the heat pump. Using emergency heat in this scenario is an unnecessary and expensive manual override.
• Myth 2: "Emergency heat warms the house faster."While electric resistance heating provides immediate, direct heat, the idea that it warms your house significantly faster than a properly functioning heat pump with auxiliary heat is often a costly myth. The sheer energy consumption doesn't necessarily translate to dramatically quicker heating, especially not enough to justify the exponential increase in your electricity bill.
• Myth 3: "It's my primary heat source in winter."Absolutely not. Emergency heat is an expensive, temporary backup. It is not designed to be a long-term or primary heating solution. Relying on it continuously will lead to financial strain and potentially unnecessary wear on the electric heating elements.

The Consequences of Improper Use

The most significant consequence of running emergency heat incorrectly is the severe impact on your energy consumption and, subsequently, your utility bills. This is not a minor increase; it's a dramatic jump that catches many homeowners by surprise.

• Astronomical Energy Consumption: As we discussed, emergency heat relies on electric resistance heating. These heat strips consume massive amounts of electricity to generate heat. Unlike a heat pump that efficiently moves heat, these strips convert every watt of electricity into heat directly. While 100% efficient in conversion, the sheer volume of electricity required is immense.
• Skyrocketing Costs: The numbers speak for themselves. Emergency heat can dramatically lift your electricity bill, costing up to 6 times more than normal heat pump operation. Consider this statistic: a normal heat pump running at 30 degrees Fahrenheit for one week might use around 252 kilowatt-hours (kWH). If you switch to emergency heat when it's 10 degrees Fahrenheit, that same week could see an additional 1260 kWH, resulting in a bill that's nearly six times higher! For homeowners in Wakulla, Leon, and Franklin Counties, this can mean hundreds of extra dollars on a single month's bill. We've seen the shocked faces when those bills arrive, and we want to help you avoid that unpleasant surprise.
• Potential Equipment Strain: While the auxiliary heating elements are robust, continuous, unnecessary use of emergency heat can put additional, unwarranted strain on these components. While it might not cause immediate damage, it certainly doesn't contribute to the longevity or optimal performance of your overall HVAC system.

Using emergency heat should be a last resort, a temporary measure to maintain warmth and prevent frozen pipes until your heat pump can be repaired. It's a lifesaver in a true emergency, but a budget-buster if misused.

Safety, Maintenance, and Preparedness

Being prepared for winter means more than just having a working heating system; it means understanding how to use all its features safely and efficiently. Proactive measures and system checks can save you from unexpected discomfort and expense.

How to Test Your Emergency Heat Setting

It's a good idea to know if your emergency heat is functioning before you actually need it. We recommend testing it as part of your annual HVAC maintenance or before the coldest parts of winter arrive.

Here’s how to perform a simple test:

1. Set your thermostat to a temperature above your current indoor temperature. This ensures your system calls for heat.
2. Manually switch your thermostat to the "EM Heat" setting. You should see the "EM Heat" indicator light illuminate.
3. Listen for your outdoor unit. It should not be running.
4. Feel the air coming from your vents. Within a few minutes, you should feel warm air. This confirms your electric resistance coils are working.
5. After a few minutes, switch your thermostat back to "Heat" or "Off." Do not leave it on emergency heat for extended periods during a test.

If you don't feel warm air or if your outdoor unit is still running in "EM Heat" mode, contact us. We can inspect your system and ensure your emergency heat is ready when you need it.

Safety Considerations for Emergency Heating

While your central emergency heat system is generally safe when functioning correctly, it's crucial to understand its limitations and consider overall home heating safety, especially during power outages.

• Emergency Heat Requires Electricity: Unlike some gas furnaces, your electric emergency heat strips require a significant amount of electricity to operate. If you experience a power outage in Wakulla, Leon, or Franklin Counties, your emergency heat will not work. This highlights the importance of having an alternative plan for heating during extended blackouts.
• Generators and Central Electric Heat Strips: Most portable generators are not powerful enough to run your home's central electric heat strips. These strips draw a very high amperage. While a generator might power a few space heaters or essential appliances, it's unlikely to handle your entire HVAC system's emergency heat. If you plan to use a generator for heating, ensure it's properly sized and consult with an electrician for safe installation.
• Alternative Heating Safety During Power Outages: If you find yourself without power, and thus without your central emergency heat, remember these critical safety guidelines:
  • Never use your oven or gas range to heat your home. This is extremely dangerous, producing carbon monoxide and posing a fire risk.
  • Space Heater Safety: If using portable electric space heaters (and you have generator power), ensure they are UL-certified. Keep them at least three feet away from anything flammable (curtains, furniture, bedding). Place them on a hard, non-flammable surface, and plug them directly into a wall outlet – avoid extension cords, as space heaters draw a lot of power and can overheat cords. Turn them off when you leave the room or go to sleep.
  • Fireplace Safety: If you have a fireplace, ensure the flue is open, use a screen to prevent embers from escaping, and never leave a fire unattended.
  • Carbon Monoxide Alarms: If using any fuel-burning devices (like a generator outdoors), ensure you have working carbon monoxide detectors on every level of your home and outside sleeping areas. Carbon monoxide is an odorless, colorless, deadly gas.
  • Conserve Heat: Isolate one room, close doors, block drafts with towels, and close curtains to retain heat. For more comprehensive tips on keeping your home warm safely, especially during emergencies, we recommend checking out resources like the Heat Your Home Safely guide from the American Red Cross.

Frequently Asked Questions about Running Emergency Heat

We often get questions from homeowners in our service areas about their heat pump and emergency heat settings. Here are some of the most common ones:

Why is my "EM Heat" light on if I didn't turn it on?

This is a critical signal! If your "EM Heat" light is illuminated on your thermostat and you didn't manually switch it to that setting, it almost always indicates a problem with your heat pump. Your system has likely detected a malfunction or failure in the heat pump's operation and has automatically engaged the emergency heat as a fail-safe to prevent your home from getting too cold. This is your system's way of telling you, "Houston, we have a problem!" It's a clear sign that you need to contact us for professional heat pump service immediately.

How long can I run my emergency heat?

You should only run your emergency heat for the shortest time possible. It is designed to be a temporary bridge, keeping your home warm and preventing issues like frozen pipes until your primary heat pump can be inspected and repaired by a professional technician. As we've discussed, its high energy consumption makes it an unsustainable and costly long-term solution. Our goal is always to get your efficient heat pump back up and running as quickly as possible.

What is the heat pump defrost cycle? Is that emergency heat?

No, the heat pump defrost cycle is not the same as running emergency heat, although it can sometimes cause confusion. The defrost cycle is a normal, automatic function of your heat pump, especially when outdoor temperatures are near or below freezing (around 28-35 degrees Fahrenheit).

Here's how it works: When your heat pump extracts heat from cold outdoor air, moisture in the air can condense and freeze on the outdoor coils, forming frost or ice. If too much ice builds up, it reduces the system's efficiency. To clear this, your heat pump periodically goes into a "defrost mode." During this cycle:

• The outdoor fan temporarily stops.
• The system briefly reverses its refrigerant flow, essentially acting like an air conditioner for a few minutes to send warm refrigerant through the outdoor coils, melting the ice.
• You might see steam rising from the outdoor unit or hear a "whooshing" sound, which is completely normal.
• While the outdoor unit is defrosting, your thermostat will typically engage the auxiliary (AUX) heat strips to ensure that only warm air continues to circulate inside your home, preventing a cold draft.

Defrost cycles usually last for a few minutes (often 5-15 minutes) and occur every 30, 60, 90, or 120 minutes, depending on the system and conditions. It's a sign that your heat pump is working correctly to maintain its efficiency in cold weather, not that it's broken.

Conclusion: Stay Warm and Smart This Winter

We understand that keeping your home warm and comfortable is a top priority, especially during the colder months here in Wakulla, Leon, and Franklin Counties. As we've explored, running emergency heat is a powerful tool, but one that comes with significant costs if misused.

To recap, emergency heat is for true emergencies only—when your heat pump is genuinely broken or severely compromised. It's not for simply cold days, nor is it a magic button to heat your home faster. Misusing it can lead to electricity bills that are up to six times higher than normal, causing unnecessary financial strain.

Your heat pump is an incredibly efficient heating system, designed to keep you warm even when temperatures drop, often with the help of its automatic auxiliary heat. If you suspect your heat pump isn't working correctly, or if that "EM Heat" light comes on unexpectedly, don't hesitate. A malfunctioning heat pump needs an expert's touch to diagnose and repair the issue promptly and efficiently.

Since 1991, our family-owned and operated business has been dedicated to delivering honest, reliable, and compassionate HVAC service. We take pride in exceeding customer expectations with strong work ethics and expert care, ensuring comfort, quality, and trust in every job we do.

For expert heat pump service in Wakulla, Leon, and Franklin Counties, contact us today! We're here to help you stay warm and smart this winter. Learn more about our heat pump services and how we can assist you.