If you own a heat pump in Melbourne, Palm Bay, or anywhere in Brevard County, you may have noticed the emergency heat setting on your thermostat and wondered what it does. Understanding heat pump emergency heat mode is especially important for Florida homeowners because our mild winters mean the feature works differently here than in colder climates. Knowing when and how to use emergency heat can prevent equipment damage, keep your family comfortable, and avoid unnecessarily high electric bills. Inlet Mechanical’s licensed HVAC technicians help homeowners understand their heating systems and make smart decisions year-round.
How a Heat Pump Normally Heats Your Home
Before diving into emergency heat, it helps to understand how your heat pump works in standard heating mode. A heat pump is essentially an air conditioner that can run in reverse. During winter, it absorbs heat energy from the outdoor air and transfers it inside. Even when outdoor temperatures drop to 40 or 50 degrees in Florida, there is still enough heat energy in the air for the system to work efficiently.
In normal heating mode, the heat pump uses the compressor and outdoor coil to extract heat, then the reversing valve directs the warm refrigerant to the indoor coil where a fan distributes the heated air through your ductwork. This process is remarkably efficient, typically producing two to three times more heat energy than the electricity it consumes. That efficiency is measured as the Coefficient of Performance (COP), and a well-maintained heat pump in Florida’s mild climate usually achieves a COP of 2.5 to 3.5.
What Emergency Heat Mode Actually Does
Emergency heat, sometimes labeled “EM Heat” or “Aux Heat” on your thermostat, bypasses the heat pump’s normal cycle entirely. When you switch to emergency heat, the system shuts down the outdoor unit (compressor and fan) and relies solely on the backup heating element inside the indoor air handler. In most Florida homes, this backup element is an electric resistance heat strip.
Electric resistance heat is straightforward: electricity flows through a metal element that gets hot, and the blower pushes air across it. While it does produce heat, it is dramatically less efficient than the heat pump cycle. Electric resistance heat has a COP of 1.0, meaning it produces exactly one unit of heat for every unit of electricity consumed. Compare that to the heat pump’s COP of 2.5 to 3.5, and you can see why emergency heat costs two to three times more to operate.
Some Florida homes have heat pumps paired with gas furnaces as the backup heat source, known as a dual-fuel system. If you have this setup, emergency heat activates the gas furnace instead of the heat pump. Dual-fuel systems are less common in Brevard County but are found in some newer construction.
When to Use Emergency Heat in Florida
In Florida, there are only a few situations where activating emergency heat makes sense:
The outdoor unit is damaged or not functioning. If a storm knocks debris into your outdoor unit, a tree limb falls on it, or the compressor fails, switching to emergency heat keeps your home warm while you wait for repairs. This is the primary purpose of the emergency heat setting. It is a backup mode for when the main system cannot operate. If your outdoor unit needs attention, schedule AC repair in Melbourne, FL as soon as possible to restore normal, efficient operation.
The outdoor unit is icing over and the defrost cycle is not working. Heat pumps have an automatic defrost cycle that melts ice buildup on the outdoor coil. On rare cold and humid Florida nights (typically below 35 degrees), the coil can frost over. If the defrost cycle fails and ice keeps building, switching to emergency heat prevents compressor damage until a technician can diagnose the defrost issue.
Extreme cold snap below 30 degrees. This is rare in Brevard County, happening maybe a few nights per decade. At these temperatures, the heat pump struggles to extract sufficient heat from the outdoor air. Emergency heat supplements or replaces the heat pump cycle to maintain indoor comfort.
When NOT to Use Emergency Heat
Many homeowners in Florida switch to emergency heat when they should not, driving up their electricity bills unnecessarily. Avoid using emergency heat in these situations:
- It is a normal cool morning (40 to 55 degrees): Your heat pump is designed to handle these temperatures efficiently. Let it work.
- The house is heating slowly: Heat pumps produce lower-temperature air than furnaces (about 90 to 100 degrees versus 130 to 140 degrees from a furnace), so they feel different even when working correctly. Be patient. The system will reach your set temperature.
- You want faster heating: While emergency heat may warm the house slightly faster in some cases, the energy cost is two to three times higher. The tradeoff is almost never worth it in Florida’s mild climate.
- As a regular heating mode: Emergency heat is for emergencies only. Running it as your primary heat source can cost an additional $100 to $200 or more per month in electricity during winter.
Inlet Mechanical offers comprehensive residential HVAC services including heat pump diagnostics, defrost cycle repair, and seasonal maintenance that keeps your system running efficiently all winter.
Frequently Asked Questions
Is it normal for my emergency heat light to come on briefly during cold mornings?
Yes. Most heat pump thermostats automatically activate the auxiliary heat strips temporarily when there is a large gap between the current temperature and your set temperature, or during the defrost cycle. This is normal operation controlled by the thermostat and is different from you manually switching to emergency heat mode. The “Aux Heat” indicator lighting up briefly is expected. If it stays on constantly, that could indicate a problem with the heat pump that needs professional attention.
How much more does emergency heat cost compared to normal heat pump operation?
Electric resistance emergency heat costs roughly two to three times more than normal heat pump operation per hour of run time. According to the U.S. Department of Energy, a heat pump delivers 1.5 to 3 times more heat energy to a home than the electrical energy it consumes, while resistance heat delivers a 1-to-1 ratio. For a typical Brevard County home, running emergency heat for a full 24-hour period instead of the heat pump could add $15 to $30 to your electricity bill for that single day.
My heat pump is blowing cool air in heating mode. Should I switch to emergency heat?
First, check your thermostat settings to make sure it is set to “Heat” and not “Cool” or “Auto.” If the setting is correct and the air coming from the vents feels noticeably cool (below room temperature), there may be a refrigerant issue, a stuck reversing valve, or a compressor problem. Switching to emergency heat will keep you warm temporarily, but you should call a licensed HVAC technician (License CMC1250858) promptly to diagnose and repair the underlying issue.
Understanding heat pump emergency heat mode helps Florida homeowners avoid wasting energy and identify real problems with their heating system. If you are unsure whether your heat pump is operating correctly, Inlet Mechanical’s licensed technicians provide expert diagnostics and repair throughout Melbourne, Palm Bay, and Brevard County. Call (321) 723-0858 or contact us online to schedule a heat pump inspection today.
Written & Reviewed By
Inlet Mechanical Team
The Inlet Mechanical team brings over 85 years of combined experience in HVAC, plumbing, and mechanical construction across Florida. Our licensed professionals hold Florida Mechanical HVAC License (CMC1250858) and Florida Plumbing License (CFC1433105), along with EPA Section 608 certifications. Based in Brevard County, we serve residential, commercial, and industrial clients with expert knowledge of Florida building codes, climate-specific HVAC solutions, and local plumbing requirements. Every article is reviewed by our licensed technicians to ensure accuracy and practical value for Melbourne-area homeowners and businesses.
Last Updated: February 18, 2026