EM Heat On Honeywell Thermostat: How and When To Use?

EM Heat On Honeywell Thermostat: How and When To Use?

When the winter weather starts to take a toll, homeowners rely on their heating systems to keep their homes warm and comfortable. One commonly used system is the electric heating system, also known as EM heat. This type of heating is controlled by a thermostat, and for Honeywell thermostats, understanding how and when to use EM heat is essential. In this article, we will discuss what EM heat is, why it is beneficial, and how to use it effectively on your Honeywell thermostat. By the end, you will have a better understanding of EM heat and be able to use it confidently during the colder months.

Modes of Your Heat Pump

Modes of Your Heat Pump

A heat pump is a mechanical device that is used for transferring heat from one location to another. It can be used for both heating and cooling purposes and is an energy-efficient alternative to traditional heating and cooling systems. The modes of a heat pump refer to the different ways in which it operates and is controlled. In this article, we will discuss the different modes of a heat pump and their functionalities.

1. Heating Mode:
The heating mode is the primary mode of a heat pump, and it is used to heat a space. In this mode, the heat pump extracts heat from the outside air, even in cold weather, and transfers it to the interior of a building. The heat pump’s compressor compresses the refrigerant, which increases its temperature and sends it to the indoor unit. The indoor unit contains a fan that circulates the warm air throughout the space.

2. Cooling Mode:
The cooling mode of a heat pump is used to cool a space during hot weather. In this mode, the heat pump removes heat from the room and transfers it outside. The heat pump’s refrigerant flows in the opposite direction as it does in the heating mode. The outdoor unit acts as the evaporator, while the indoor unit functions as the condenser. The cool air is then distributed throughout the space by the indoor fan.

3. Auto Mode:
Some modern heat pumps have an auto mode, which is a combination of the heating and cooling modes. In this mode, the heat pump senses the temperature inside the space and automatically switches between heating and cooling, depending on the desired temperature set by the user. This mode is convenient for users as it eliminates the need to manually switch between heating and cooling modes.

4. Fan Only Mode:
The fan only mode allows the heat pump to operate as a fan, without heating or cooling the space. This mode is useful during mild weather when you need air circulation but not heating or cooling. It is also useful for circulating fresh air into the space.

5. Emergency Heat Mode:
Emergency heat mode is used when the outdoor condenser is not working correctly. In this mode, the heat pump switches to a backup heating source, such as an electric resistance heater. This mode is only for temporary use until the outdoor unit is repaired.

6. Defrost Mode:
The defrost cycle is activated during the heating mode in cold weather when the outdoor unit is covered with ice or frost. The heat pump uses a reversing valve to circulate warm refrigerant through the outdoor unit, melting the ice or frost and allowing the unit to operate efficiently.

In conclusion, heat pumps have various modes to operate in, providing the user with flexibility and control over their heating and cooling needs. With technological advancements, heat pumps are becoming more efficient and offer more diverse modes to cater to different weather conditions and user requirements.

What is EM Heat?

What is EM Heat?

EM heat, also known as Emergency Heat, is a backup heating option in a heating and cooling system. It is typically found in heat pumps, which are devices that transfer heat from one location to another. Heat pumps are primarily used for cooling in the summer and heating in the winter. However, in extremely cold weather conditions, they may struggle to extract enough heat from the outside air to keep the interior of a building warm. This is where EM heat comes into play.

EM heat is a supplemental heating system that is automatically activated when the outside temperature drops too low for the heat pump to operate efficiently. It is usually powered by electricity and can provide a significant amount of additional heat to maintain a comfortable temperature inside the building.

When the EM heat option is activated, the heat pump shuts off, and the auxiliary heating elements in the system turn on. These elements generate heat through electrical resistance, much like a traditional electric heater. EM heat is capable of producing more heat in a shorter amount of time compared to the heat pump, making it an effective backup for extremely cold weather conditions.

One of the primary benefits of EM heat is that it allows the heat pump to rest and prevents it from working too hard in harsh weather conditions, which can lead to wear and tear on the system. This can, in turn, increase the lifespan of the heat pump and prevent frequent repairs or replacement.

However, using the EM heat feature can result in higher energy bills as it consumes more electricity than the heat pump. Therefore, it is essential to only activate EM heat when necessary and switch back to the heat pump as soon as the temperature rises.

EM heat is a crucial feature in areas with harsh winters, where heat pumps alone may not be enough to keep a building warm. It provides a reliable and efficient backup heating option, ensuring comfort and safety during extreme weather conditions.

Warning Against Switching to EM Heat Manually

Warning Against Switching to EM Heat Manually

As a civil engineer, I would like to warn about the potential risks and drawbacks of manually switching to EM (Emergency) Heat. While it may seem like an immediate solution in case of a heating system malfunction, it is essential to understand the potential consequences and drawbacks of this action.

First and foremost, EM heat should only be used as a temporary measure, as it is designed to provide heat in an emergency situation. Using it as a long-term solution can result in higher energy bills and can put undue strain on your heating system. This is because EM heat consumes significantly more energy than regular heating, making it an expensive option.

Moreover, manually switching to EM heat can also lead to a sudden spike in temperature, causing discomfort and potentially damaging the heating system. This is particularly concerning for older systems that may not be equipped to handle such a sudden change in temperature. Constantly switching between regular heating and EM heat can also put unnecessary strain on the system, leading to potential breakdowns and costly repairs.

Additionally, EM heat may not be able to adequately heat your entire home or building. It is typically only designed to provide heat for a limited area or for a short period, making it unsuitable for prolonged use. This can result in uneven heating, making some areas of your home uncomfortably warm while others remain cold.

In some cases, manually switching to EM heat may also void the warranty of your heating system. This is because using EM heat for extended periods and at high temperatures can cause damage to the system, which may not be covered by the manufacturer’s warranty.

It is also crucial to note that EM heat is not as energy-efficient as regular heating and can have a significant impact on your utility bills. In the long run, using EM heat as a substitute for regular heating can be financially burdensome.

In conclusion, while EM heat can be a useful solution in emergency situations, it should only be used as a temporary measure. As a civil engineer, I would strongly advise against manually switching to EM heat as a long-term solution for heating issues. It is essential to consult a qualified HVAC technician to properly diagnose and fix any heating system malfunctions to avoid potential risks and costs associated with using EM heat.

When to Use EM Heat

When to Use EM Heat

EM heat, or emergency heat, is a supplemental heating option in a HVAC system that is designed to be used in very cold temperatures. It is typically controlled by a switch on the thermostat and activates electric resistance heating elements in the heat pump system. As a civil engineer, it is important to understand when to use EM heat in order to properly design and maintain HVAC systems in buildings.

The use of EM heat may be necessary in situations where the temperature is too cold for the heat pump to efficiently provide heat. Heat pumps are most effective when the outdoor temperature is above freezing, as they use the air outside to warm the air inside a building. However, when the temperature drops below freezing, the heat pump may struggle to extract enough heat from the outdoor air to sufficiently warm the indoor space. This is where EM heat comes in.

EM heat is most commonly used in situations where the outdoor temperature is consistently below freezing for an extended period of time, such as in colder climates or during extreme weather events. In these situations, the heat pump alone may not be able to keep the indoor space at a comfortable temperature, so EM heat can be used to provide additional heat.

Another situation where EM heat may be necessary is if the heat pump system is not functioning properly. In the event of a malfunction or maintenance issue, the heat pump may not be able to provide heat at all. In this case, EM heat can be used as a backup until the issue with the heat pump is resolved.

In addition, EM heat may be used to defrost the outdoor unit of a heat pump. Heat pumps use a refrigerant cycle to transfer heat, and in colder temperatures, frost and ice can build up on the outdoor unit, hindering its ability to function. EM heat can be activated to briefly warm up the outdoor unit and melt any accumulated ice, allowing the heat pump to resume normal functioning.

However, it is important to note that EM heat should not be used as the primary heating source, as it can be more expensive to operate than the heat pump. It is meant to be used as a temporary solution in very cold temperatures or in emergency situations.

In conclusion, EM heat can be a useful tool in maintaining a comfortable indoor temperature in cold climates or during extreme weather conditions. As a civil engineer, it is important to consider and design for the use of EM heat in HVAC systems, taking into account the specific climate and weather conditions of the building’s location. Proper use of EM heat can help ensure the efficient and effective operation of HVAC systems for buildings.

Features of EM Heat

Features of EM Heat

The abbreviation EM in EM Heat stands for “emergency heat,” which refers to an auxiliary heating system typically used in HVAC (heating, ventilation, and air conditioning) systems. EM Heat serves as a backup heating system that operates when the primary heat source is not functioning or when outdoor temperatures drop below a certain point.

Here are some of the key features of EM Heat:

1. Provides Supplemental Heat: EM Heat serves as a backup heating system, providing additional heat when the primary heating system is not working. This is particularly useful during extreme weather conditions when the primary heat source may not be able to adequately heat the building.

2. Uses Electric Resistance Heating: EM Heat uses electric resistance heating to generate heat, making it independent of any other fuel source. This means it can operate even if the gas supply is disrupted.

3. Efficient Heat Source: Electric resistance heating is highly efficient, with almost 100% of the energy used being converted into heat. This makes EM Heat an energy-efficient option for backup heating.

4. Quick Heat Output: EM Heat can provide heat much quicker than a primary heat source, as there is no need for a warm-up period. This is particularly helpful during cold weather when immediate heat is needed.

5. Automatic Activation: In most HVAC systems, EM Heat is automatically activated when the primary heat source is not sufficient. This ensures that the building remains warm and comfortable despite any malfunction in the primary heating system.

6. Cost-effective: EM Heat uses electricity, which is often cheaper than other fuel sources. This makes it a cost-effective option for backup heating, especially in areas where electricity is relatively inexpensive.

7. Easy to Maintain: Since EM Heat is an electric system, it requires minimal maintenance compared to other heating systems. This makes it a popular choice among homeowners and building managers.

8. Long Lifespan: EM Heat has a longer lifespan than other heating systems, as it doesn’t have any moving parts that can wear out. This makes it a reliable backup heating source, which can last for many years without needing to be replaced.

In conclusion, EM Heat serves as an efficient and cost-effective backup heating system, ensuring that a building remains warm and comfortable during emergency situations. Its automatic activation, low maintenance, and long lifespan make it a popular option for homeowners and building managers alike.

In Case of Emergency

In Case of Emergency

In case of an emergency, it is important to have a plan in place to ensure safety and minimize damage. As a civil engineer, I understand the vital role that emergency planning plays in disaster management and response. Proper emergency planning can save lives, protect infrastructure, and aid in recovery efforts.

One of the first steps in emergency planning is to identify potential risks and hazards in an area. This can include natural disasters such as earthquakes, hurricanes, and floods, as well as man-made hazards like fires, chemical spills, and explosions. Through risk assessment and analysis, civil engineers can determine the potential impact of these hazards and develop mitigation measures to minimize their effects.

Designing structures and infrastructure that are resilient and able to withstand potential hazards is another crucial aspect of emergency preparedness. This includes incorporating features such as earthquake-resistant building techniques, flood-proofing, and fire-resistant materials. Civil engineers also play a key role in designing emergency exits, evacuation routes, and emergency systems such as fire alarms and sprinklers in buildings.

In the event of an emergency, quick and efficient responses are critical. Civil engineers work closely with emergency response teams to assess damage to infrastructure and determine the safety of buildings and roads. They use their expertise to inspect and assess the safety of structures, bridges, and roads before and after an emergency, ensuring that they are safe to use.

Communication and coordination are also essential in emergency situations. As a civil engineer, I am trained to work in conjunction with other professionals such as first responders, city planners, and government agencies to effectively manage emergencies. We also often serve as liaisons between government agencies and the public, providing critical information and updates during an emergency.

Aside from immediate response, civil engineers also play a role in the long-term recovery and rehabilitation of affected areas. This may include rebuilding damaged structures, repairing infrastructure and utilities such as roads and water systems, and implementing disaster-proof designs to prevent or minimize future damages.

In conclusion, in an emergency, civil engineers play a vital role in keeping communities safe and minimizing damage to infrastructure. Through risk assessment, design, response, and recovery efforts, we are committed to ensuring the safety and well-being of the public.



Cost is a fundamental concept in the field of civil engineering as it plays a crucial role in all stages of a project’s lifecycle. It refers to the expenses incurred to build, maintain, and operate any infrastructural project. As a civil engineer, estimating and managing project costs is a critical aspect of our job as it directly affects the feasibility, profitability, and success of a project.

The cost of a civil engineering project typically includes material costs, labour costs, equipment costs, and other indirect expenses such as permits, design fees, and insurance. It is essential to determine these costs accurately during the planning and design phase to ensure the project’s financial viability and avoid any delays or setbacks.

One of the primary factors that affect cost in civil engineering projects is the complexity of the design. The more complex the design, the higher the costs involved. This is because complex designs require more effort, time, and resources to construct and maintain.

Another crucial factor that affects cost is the site conditions. The site’s topography, soil type, and accessibility all play a role in determining the cost of a project. If the site is challenging to access or has poor soil conditions, it can drive up the costs of construction significantly.

Construction methods and techniques also greatly impact the project’s cost. Some construction methods may require more labour, while others may need expensive specialized equipment, both of which can increase the cost of the project.

Moreover, changes and unforeseen circumstances during the construction phase can also significantly impact the project’s cost. This is why it is crucial to have a contingency plan in place to handle any potential changes or issues that may arise.

As a civil engineer, it is our responsibility to utilize cost-effective design and construction techniques to ensure that a project is completed within the allocated budget. This involves continuously monitoring and updating cost estimates, managing resources efficiently, and effectively evaluating and controlling expenses.

In conclusion, cost management is a critical aspect of civil engineering, and it requires a comprehensive understanding of various factors that can influence a project’s cost. As professionals, it is our duty to strike a balance between quality and cost to deliver sustainable and successful projects.

How to Know if EM Heat is Active

How to Know if EM Heat is Active

In many HVAC systems, there is an option to use emergency heat or EM heat during extremely cold weather. This function provides extra heat to the house when the primary heating system is unable to keep up with the demand. It is important to know if EM heat is active so that you can adjust the temperature accordingly and avoid potential damage to your heating system.

Here are some ways to determine if EM heat is active in your HVAC system:

Check the Thermostat Display: The quickest way to know if EM heat is active is to check the display on your thermostat. In most cases, the word “EM Heat” or “Emergency Heat” will appear on the screen when the function is active. Some thermostats also have a light or indicator specifically for EM heat.

Feel the Air Coming from the Vents: When EM heat is active, you should be able to feel a significant increase in the temperature of the air coming from your vents. EM heat uses a backup heating source, usually electric resistance coils, to heat the air, so it will be warmer than the air from your primary heating system.

Listen for Changes in the Heating System: If you have a heat pump, the outdoor unit should make a different noise when EM heat is active. This is because the heat pump is not in use and only the backup heating source is running. If you have a furnace, you may also notice a change in the sound of the blower motor when EM heat is active.

Observe the Outdoor Unit: For heat pumps, the outdoor unit will need to defrost when EM heat is active. This is because the heat pump is not in use and the ice that has accumulated on the unit needs to melt. If you notice the outdoor unit defrosting, it is a good indication that EM heat is active.

Check the Energy Usage: Since EM heat uses electric resistance coils as the heating source, it consumes more energy compared to a heat pump or furnace. If you notice a significant increase in your energy usage during extremely cold weather, it could be a sign that EM heat is active.

In conclusion, it is important to know if EM heat is active in your HVAC system so that you can monitor the temperature and energy usage, as well as avoid potential damage to your heating system. If you are unsure whether your system has EM heat or how to activate it, it is best to consult an HVAC professional for assistance.


In conclusion, EM heat on a Honeywell thermostat can be a useful heat source in certain situations, such as during extreme cold or when the heat pump is not functioning properly. It is important to understand when and how to use EM heat to avoid excessive energy consumption and potential damage to your thermostat. By following the guidelines provided in this article, you can effectively utilize the EM heat setting on your Honeywell thermostat to ensure comfortable and efficient heating in your home. Remember to always consult your thermostat manual or a professional for further guidance, and make sure to properly maintain your system for optimal performance. With the right knowledge and proper usage, EM heat on your Honeywell thermostat can be a valuable tool in keeping your home warm and cozy.

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