A makeup air unit is an essential component of heating, ventilation, and air conditioning (HVAC) systems. It plays a critical role in providing fresh air to replace the indoor air that is exhausted by various mechanical systems in a building. Did you know that without a makeup air unit, buildings can experience negative pressure, leading to poor indoor air quality and discomfort for occupants? Makeup air units are designed to supply a controlled amount of fresh outside air into the building, ensuring proper ventilation and maintaining a comfortable and healthy environment.

Makeup air units have a long history and have evolved significantly over time. In the past, buildings relied on natural infiltration for makeup air, but as buildings became more energy-efficient, this method was no longer sufficient. Today, makeup air units are designed to be energy-efficient and have advanced features such as heat recovery systems that minimize energy waste. They are an effective solution to combat indoor air pollution, as they help remove contaminants and replenish oxygen levels. In fact, studies have shown that proper ventilation, provided by makeup air units, can significantly improve indoor air quality and reduce the risk of respiratory illnesses among occupants.

what is a makeup air unit

Understanding Makeup Air Units

A makeup air unit is an essential component in HVAC systems that helps maintain a balanced indoor air quality by supplying fresh outdoor air to replace the air removed from the building. It is commonly used in commercial and industrial settings where exhaust systems, such as kitchen hoods or manufacturing processes, create negative pressure within the building. This negative pressure can cause a range of issues, including inefficient exhaust, backdrafting of combustion appliances, and uncomfortable indoor environments.

By introducing makeup air into the building, the makeup air unit helps equalize the pressure and ensure proper ventilation. It is typically installed in conjunction with exhaust systems to provide a continuous flow of fresh air, improving air quality and creating a comfortable and safe environment for occupants.

In the following sections, we will delve deeper into the workings of makeup air units, their benefits, and how they contribute to maintaining a healthy indoor environment.

Why Do You Need a Makeup Air Unit?

Before we explore the details of makeup air units, let’s understand why they are necessary in certain environments. Here are a few key reasons why you may need a makeup air unit:

  • To prevent negative pressure in the building: When exhaust systems remove air from a space, it creates a vacuum effect that can lead to issues like backdrafting and poor ventilation. A makeup air unit helps counteract this negative pressure by supplying fresh air.
  • To maintain indoor air quality: Without proper ventilation, pollutants and contaminants can accumulate indoors, leading to health issues. A makeup air unit ensures a continuous flow of fresh outdoor air, improving air quality and creating a healthier environment.
  • To enhance energy efficiency: Makeup air units can be equipped with energy recovery systems that transfer heat or coolness from the outgoing exhaust air to the incoming fresh air. This process helps reduce the energy required to condition the makeup air, resulting in improved energy efficiency.
  • To comply with building codes and regulations: Many building codes and regulations require the proper installation of makeup air units in commercial and industrial settings to ensure the health, safety, and comfort of building occupants.

Components of a Makeup Air Unit

A makeup air unit consists of several components that work together to supply fresh air and maintain proper ventilation. These components include:

  • Air Intake: The air intake is the opening through which fresh outdoor air enters the unit. It can be equipped with filters to remove dust, pollen, and other airborne particles.
  • Supply Fan: The supply fan is responsible for drawing outdoor air into the unit and distributing it throughout the building. It ensures a continuous flow of fresh air.
  • Heating or Cooling Coils: Makeup air units often include heating or cooling coils to condition the incoming air, ensuring it reaches the desired temperature.
  • Energy Recovery System: Some makeup air units feature an energy recovery system that transfers heat or coolness from the outgoing exhaust air to the incoming fresh air, improving energy efficiency.
  • Controls: Controls are used to monitor and adjust the operation of the makeup air unit, including fan speed, temperature, and air quality sensors.

Benefits of Using a Makeup Air Unit

Using a makeup air unit in your HVAC system can provide several benefits. Here are some key advantages:

  • Improved Indoor Air Quality: By supplying fresh outdoor air and removing stale air, a makeup air unit helps improve the overall indoor air quality, reducing the presence of pollutants and contaminants.
  • Prevents Negative Pressure: Makeup air units counteract the negative pressure created by exhaust systems, preventing issues like backdrafting, inefficient exhaust, and uncomfortable indoor conditions.
  • Enhanced Energy Efficiency: Makeup air units can be equipped with energy recovery systems, allowing for heat or coolness transfer between incoming and outgoing air. This feature helps reduce energy consumption and enhances overall energy efficiency.
  • Compliance with Building Codes: Installing a makeup air unit ensures compliance with building codes and regulations that require proper ventilation and air quality standards in commercial and industrial settings.

Maintenance and Considerations for Makeup Air Units

Proper maintenance of makeup air units is crucial to ensure their efficient and effective operation. Here are some maintenance considerations:

  • Regular Filter Replacement: The filters in the air intake need to be inspected and replaced periodically to ensure optimal air quality and prevent dust build-up.
  • Cleaning Coils: Dirt and debris can accumulate on the heating or cooling coils, reducing their efficiency. Regular cleaning is necessary to maintain proper airflow and energy efficiency.
  • Inspecting Fans and Belts: Regularly inspecting and lubricating fans and belts can help prevent any mechanical issues and extend the lifespan of the makeup air unit.
  • Ensuring Proper Ventilation: It’s important to ensure that the makeup air unit is supplying adequate fresh air to the building. Periodic inspections and adjustments may be necessary to maintain proper ventilation rates based on occupancy and usage.
  • Monitoring Controls: Regularly check the controls and sensors to ensure they are functioning correctly and adjust settings as needed to maintain optimal performance.


A makeup air unit plays a vital role in maintaining proper ventilation, air quality, and pressure balance in commercial and industrial environments. By supplying fresh outdoor air while removing stale air, these units enhance indoor air quality, prevent negative pressure, and improve energy efficiency. Regular maintenance is necessary to ensure the efficient operation of makeup air units and compliance with building codes and regulations. If you have an exhaust system in your building, consider installing a makeup air unit to improve the comfort and health of occupants while ensuring compliance with ventilation standards.

Table: Comparison of Different Types of Makeup Air Units

Makeup Air Unit Type Advantages Disadvantages
Direct-Fired Makeup Air Unit – Provides efficient heating for outdoor air
– Lower initial cost compared to some other types
– Suitable for cold climates
– Combustion byproducts may require additional ventilation
– Not suitable for areas with strict air quality regulations
Indirect-Fired Makeup Air Unit – Ideal for spaces with strict ventilation requirements
– Does not introduce combustion byproducts into the building
– Can be used for heating and cooling
– Higher initial cost compared to direct-fired units
– Requires separate energy source for heating or cooling
Recirculating Makeup Air Unit – Energy efficient as it recirculates part of the indoor air
– Lower initial cost compared to direct or indirect-fired units
– Suitable for spaces with limited outdoor air requirements
– May not provide enough outdoor air for certain environments
– Requires additional outdoor air supply for proper ventilation

Key Takeaways: What is a Makeup Air Unit?

  • A makeup air unit is a ventilation system that replaces stale air with fresh outdoor air in commercial buildings and homes.
  • It helps maintain proper indoor air quality by removing pollutants and odors and providing fresh air for occupants.
  • A makeup air unit is typically installed in areas where exhaust fans, such as in kitchens or bathrooms, create negative pressure.
  • It can be beneficial in reducing energy costs by improving HVAC system efficiency and preventing drafts.
  • Makeup air units come in various sizes and configurations to suit different building requirements.

Frequently Asked Questions

In this section, we will answer some commonly asked questions about makeup air units.

1. How does a makeup air unit work?

A makeup air unit is designed to provide fresh, outdoor air to a building or space to replace the air that is exhausted. It works by pulling in fresh air from outside, filtering it, and then distributing it evenly throughout the building using a system of ducts. This helps maintain proper air balance and ventilation, preventing negative air pressure and improving indoor air quality.

Additionally, makeup air units can be equipped with heating, cooling, and dehumidification capabilities to ensure that the supplied air is at the desired temperature and humidity level. They are often used in commercial kitchens, industrial facilities, and other spaces where significant exhaust occurs, such as from range hoods or process equipment.

2. What are the benefits of using a makeup air unit?

There are several benefits to using a makeup air unit:

First, it helps maintain a balanced airflow in the building, preventing negative air pressure. This is important for the efficient operation of exhaust systems and for the comfort and well-being of occupants.

Second, a makeup air unit can improve indoor air quality by supplying fresh, filtered air to replace the air that is exhausted. This can reduce the buildup of pollutants, odors, and moisture in the building.

Lastly, makeup air units with heating, cooling, and dehumidification capabilities can provide conditioned air, ensuring a comfortable and controlled indoor environment regardless of the outdoor conditions.

3. When is a makeup air unit necessary?

A makeup air unit is necessary in spaces where significant exhaust occurs, and the replacement air needs to be provided to maintain proper air balance and ventilation. This includes commercial kitchens, industrial facilities, laboratories, and manufacturing plants.

It is also commonly used in buildings that are tightly sealed or have high energy efficiency standards, as these can create negative air pressure and lead to issues with the performance of exhaust systems and the overall comfort of occupants.

4. Is there any maintenance required for a makeup air unit?

Yes, like any HVAC system, a makeup air unit requires regular maintenance to ensure optimal performance and longevity. This can include changing filters, cleaning coils, inspecting and lubricating fans and motors, and checking for any leaks or damage in the ductwork.

It’s also important to schedule regular professional inspections to identify and address any potential issues before they become major problems. Proper maintenance ensures that the makeup air unit functions effectively and efficiently, providing the desired indoor air quality and comfort.

5. Can a makeup air unit be customized for specific needs?

Yes, makeup air units can be customized to meet specific requirements and needs. They can be designed with different capacities, filtration options, heating and cooling capabilities, and control systems to ensure they are suitable for the particular application.

Working with a professional HVAC contractor, the makeup air unit can be tailored to the size and layout of the building, the airflow requirements, and any specific environmental conditions that need to be addressed.

what is a makeup air unit 2

A makeup air unit is a device that brings in fresh outside air to replace the stale air in a building. It helps maintain proper ventilation and air quality.

These units are commonly used in commercial buildings, restaurants, and industrial spaces to supply fresh air and balance the pressure created by exhaust systems. They ensure a healthier and more comfortable environment for occupants.


  • Maria J. Morrison

    Maria is a professional Beautician and his hobby is beauty & Personal care. she has been for the last 5 years and he loves makeup while on outings as well. Based on his experience with the different types of makeup. She is sharing his opinion about various makeup so that a beginner can get started the right way. Find him onTwitter here. Happy reading.