Facts You Must Know About Heat Pumps & Emergency Heat

Dennis Howard
by Dennis Howard

Heat pumps are amazingly efficient for heating your home under most normal conditions. However, when conditions aren’t right, your heat pump depends on its emergency heating capability to keep the temperature in your house comfortable and stable. If you own a heat pump, there are some facts about emergency heating you should know.

Heat pumps extract warmth from the air outside your home and transfer it inside. When the temperature outside goes below 30 degrees Fahrenheit, the heat transfer no longer works efficiently, and your heat pump engages its emergency heating system. This emergency heat uses electric coils, which can be expensive to operate,

Understanding the facts behind your heat pumps emergency heat system and how to use it can save you hundreds of dollars over a heating system. There are some issues with heat pup emergency heat that may occur. Knowing the facts about heat pumps and emergency heating is in your best interest.

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How Does a Heat Pump Work?

A heat pump works by capturing heat in the outside air and transferring it to the air inside your home. This is a rather complicated process that operates almost like a reverse air conditioning system.

The heat pump transfers the heat from outside using the refrigeration coolant in the heat pump system. As the coolant in your HVAC system circulates into your house, it enters a set of coils. Your HVAC system fan circulates air in your house over the coil. The captured heat is transferred to your inside air warming your home.

Heat pumps work very efficiently when the outside temperature stays over 30 degrees. At temperatures below 30 degrees, the heat pump’s ability to capture warmth is degraded. As the temperature drops, the heat pump will not capture enough heat to keep your home warm. This is when your emergency heat system comes into play.

What is Emergency Heat on a Heat Pump?

If your heat pump is properly installed and the right size, it should have no problem keeping your home warm. Heat pumps work by capturing heat from the outside and bringing it inside to your home. This can be quite efficient under most circumstances. This makes heat pumps popular where temperatures don’t normally stay below thirty degrees Fahrenheit for very long outside.

However, in those times when the outside temperature falls below 30 degrees for an extended time, your heat pump may need help keeping your home at a reasonable temperature. A backup electric heat coil is installed for these times.

The emergency heat system in the heat pump can also provide heat if the heat pump fails. Since the emergency heating coils are separate from the heat pump unit, you can keep your family warm in an emergency.

How Does the Emergency Heat Usually Work on My Heat Pump?

Under normal operating conditions, your heat pump will only engage the emergency heating system when needed. If your heat pump cannot gather enough heat units from the outside air to heat your home, it will automatically start the emergency heat system.

Typically, this occurs when the temperature outside falls below thirty degrees Fahrenheit. At this temperature, the heat pump cannot effectively heat your home using the heat transfer method. The heat pump control system will start the electric heating coils to add the necessary warmth to the air in your home.

We Had a Long Cold Spell, and My Electric Bill Went Up Significantly. What’s Up?

Your heat pump depends on an electric heating array to provide emergency heat to your HVAC system. If you have a long cold snap that keeps the temperatures below thirty degrees, your heat pump relies on the emergency heat system. Running the emergency heat system can be incredibly expensive.

As the outside temperature gets colder, your HVAC system must rely on the emergency heating system more. For example, look at this chart that compares the normal operation cost for a heat pump to the cost of using the emergency heat system.

Typical Operational Cost FactorsNormal Heat Pump Operations at 30 degrees for 7 daysEmergency Heat Operations at 10 degrees for 7 days
Watts Per Hour3000 Watts3000 Watts + 15000 Watts
Hours Per Day of Operation12 Hours24 Hours + 12 Hours
Number of Days of Operation7 days7 days
Total Electricity Used in kWh252 kWh252 kWh + 1260 kWh
Average cost per kWh$0.13$0.13
Total Cost for 7 days of operation$32.75$196.56

It is easy to see why you should avoid running your emergency heating system with your heat pump. The cost of operating the electric heat system can increase your heating costs by more than 6 times.

Is Auxiliary Heat the Same as Emergency Heat?

The thermostat on some heat pump systems doesn’t indicate emergency heat but uses the term auxiliary heat. These are just different words for the same system. You may also hear the emergency heat system on your heat pump referred to as heat strips.

These are all the same sort of systems and are operated in the same way. The terminology may be slightly different, but the concept and the use are the same. The cost to operate these systems is also much the same, no matter what it is called.

Some manufacturers use both terms in their user manuals. They may refer to auxiliary heat for the electric heating automatically controlled by the thermostat or HVAC controller. The thermostat may have a setting that allows you to turn on the electric heating coils manually. Some manufacturers refer to this setting as emergency heat.

Can I Use a Programmable Thermostat with My Heat Pump?

Many people are familiar with programmable or setback thermostats. These devices allow a schedule to be created in the thermostat that will automatically lower the temperature in your home when no one is normally there. The thermostat can be programmed to bring your home back to a comfortable temperature just before you normally arrive home.

Having a setback schedule can save you money over the long term. If your family is normally out of the house for long periods during the day, reducing the temperature in the home during that time means less energy is consumed.

However, there is a problem with setback thermostats and heat pumps unless a special setback thermostat is installed. Many heat pump systems will switch on the emergency heat system if the thermostat is raised by more than two or three degrees at one time. This can quickly eliminate any savings you gained by using the setback thermostat features.

There are programmable thermostats designed for heat pump systems. Your best option is to consult with your HVAC technician to ensure that any thermostat you install is compatible with your heat pump.

My Heat Pump Thermostat Doesn’t Have an Emergency Setting

Depending on where you live, this may not be unusual. Many HVAC systems are installed without emergency heat in moderate climates and rarely see temperatures below thirty degrees. In Florida, Arizona and along the Gulf Coast, the climate makes emergency heating unnecessary. It just doesn’t get cold enough often enough to warrant the extra cost of installing the emergency heating systems.

If you want the added backup of emergency heat, you should consult with your HVAC technician about installing emergency heat on your heat pump. It is almost always possible to retrofit emergency heating to an existing heat pump system.

When Should I Turn on Emergency Heat?

Under normal circumstances, you should never have to manually engage the emergency heat settings on your heat pump thermostat. The controller and thermostat work together to manage the heating system for the most efficient operation possible.

If the heat pump controller senses that it isn’t getting enough heat from the outdoor air, it will automatically engage the emergency heat system. The heat pump controller will only use the emergency heat system as much as necessary to keep your home at the proper temperature. This is the most efficient way to operate the system.

However, if your heat pump unit suffers damage or fails, it may be necessary for you to manually switch on the emergency heating system. This should only be done in extreme situations where your heat pump unit is not working. If you face this situation, call your HVAC technician as soon as possible.

When I raise the Thermostat Setting the Red Emergency Heat Light Come On

This is not unusual on most heat pump systems. If you raise the thermostat setting manually more than a few degrees, the heat pump controller tries to comply immediately. The heat pump controller will fall back on the emergency heat system to help raise the temperature quickly.

It is best to avoid making thermostat changes of more than a few degrees at a time. If you see the emergency heat icon light up on your thermostat after raising the temperature setting, back the thermostat down a few degrees. Making small incremental changes to the thermostat will prevent the emergency heat system from operating.

Is Electricity the Only Option for Emergency Heat?

Electricity is the most common form of emergency heating used with heat pump systems. However, it is not uncommon to find emergency heat systems fueled by propane or natural gas in some areas. These systems are commonly referred to as dual fuel heat pumps.

There are advantages and disadvantages to using propane or natural gas rather than electricity.

  • Electrical systems are typically cheaper and easier to install.
  • Natural gas and propane are usually cheaper to operate from a fuel cost standpoint
  • There can be more maintenance involved with natural gas or propane systems
  • Gas systems require venting, pipe runs, and special valving and controls that add to the cost.

Most people opt for an electrically operated emergency heating system for their heat pumps. However, under certain circumstances, propane or natural gas make more sense. In areas with high electricity prices or rural areas where the electrical delivery is prone to outages, propane, or natural gas benefits.

The Red Emergency Light on My Thermostat is Lit, but There is No Heat

If you are experiencing an extreme cold spell, you should expect the emergency heating system to kick in. However, if the red indicator light on your thermostat is lit and there is no warm air coming from the vents, you may have a serious problem.

Main Control Board Problems

The most common cause of a failure in the emergency heating system on a heat pump is on the controller. The system on the controller that manages the emergency heating system is called a sequencer. These small electronic circuits manage how power is provided to each part of the heating system. If the sequencer fails, the emergency heat system may not work.

You should call an HVAC technician if you suspect a problem with the main control board of your heat pump. Trained technicians can diagnose and repair these kinds of problems quickly.

Heating Element Failures

The heating element in your emergency heat system is a series of wire coils that get hot when electricity flows through them. This constant heating and cooling of the wire coils often create problems. The wires can crack and break over time. Any debris on the wires can cause a hotspot that will lead to failure.

Any break in the wire coils means no heat from that portion of the emergency heating system. A call to your HVAC technician is your best option. Replacing a heating element is often a chore because of the location of the heating system. Some heating coils are delicate and getting a new one in place without damage takes some experience.

Thermostat Failures

It is rare for a heat pump thermostat to fail so that it prevents the emergency heating system from operating. However, nothing is impossible when it comes to electronics. In most instances, if your thermostat is bad, the only solution is to install a new thermostat. The cost of repairing a thermostat usually exceeds the cost of a new unit. Consult with your HVAC technician if you suspect that your thermostat is not operating properly.

The Red Emergency Light on my Thermostat is Blinking

If the red emergency light on your thermostat is blinking, you should take notice. A blinking red light indicates a problem with your heat pump that should be immediately addressed. In most cases, your heat pump has shut itself down for some reason.

You should check your heat pump for ice build-up or snow accumulations. If too much ice or snow accumulates on the heat pump, air cannot flow around the coils, and the system may shut down. Clean any snow or ice away from the top and sides of your heat pump, and then reset the system.

Power issues may also cause the system to go into lock-out mode. If you have suffered a black-out or brown-out power situation, your heat pump may shut itself down. Sometimes simply turning the HVAC system off and then back on will solve the problem. Be sure and check the breakers to ensure that the system has the power it needs to operate.

If you cannot get the system to reset, you should immediately call a service technician. A qualified service technician can read the error codes on your unit and quickly diagnose the problems.

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Keeping Warm at the Worst of Times

The emergency heat system on your heat pump is there to ensure that you have heat for your home and your family. If your heat pump fails in extreme weather conditions, the emergency heat system will keep you warm. Understanding how this system works and when you should use it is knowledge any heat pump owner should have.

Dennis Howard
Dennis Howard

Dennis is a retired firefighter with an extensive background in construction, home improvement, and remodeling. He worked in the trades part-time while serving as an active firefighter. On his retirement, he started a remodeling and home repair business, which he ran for several years.

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