Make-Up Air Units

Imbalanced pressure in a structure has numerous consequences from employee health to equipment damage. A make-up air unit or MUA, prevent these key issues and many more from occurring.

This article covers the basics of make-up air units, the main configurations, mounting options and manufacturers.

Commercial make up air unit

A structure that is in a negative state of pressure is dangerous, unhealthy, and expensive to operate.

Table of Contents

Make-Up Air Diagram

direct gas-fired make-up air unit diagram

The diagram above demonstrates how 100% outside air enters the MUA through the hood and is filtered before passing through motorized damper.

Once through the damper the burner heats the air directly. The heated air is then drawn into the centrifugal fan where it is pushed into the structure.

Authorized MUA Suppliers

We are the authorized distributors for the leading American manufacturers of makeup air units. We’ll be pleased to provide the ideal make up air unit for your application as authorized representatives.

For a fast quote or if you have inquiries about commercial or industrial MUA, get in touch with us.

What Does a Make-up Air Unit Do?

A make-up air unit’s job is to replaces the air in the space.

MUA replaces the air that has been expelled from a space due to general ventilation, process equipment, heaters, and other HVAC equipment. The building is brought to a neutral or pre-determined building pressure by replacing the air.

This balanced building pressure enables the facility to function as planned with maximum efficiency.

As a result, the facility has a healthy indoor air quality (IAQ), a healthy workforce, protect equipment, and decreased energy waste.

The cost of a makeup air unit is frequently recouped through energy savings resulting from fewer HVAC demands, lower exhaust demands, higher production levels, enhanced production, reduced personnel sick leave, and other comparable variables.

Advantages of a Make-Up Air Unit


To best understand a traditional makeup air system we should first start with its construction. In its most basic form, a make up air unit is a blower fan within a metal box.

These fan boxes are often modular and can be built to accommodate many requirements.

A traditional makeup air unit typically includes:

This is the basic construction, but certainly not the limitation.

Make Up Air Unit Configurations

There several configurations with a variety of heating and cooling solutions including:


Make-up air systems are utilized in commercial, institutional and industrial applications. As each segment is different they often serve a variety of functions.

Commercial Make-Up Air Systems

Commercial units include a range of customization options. Filters are typically comprised of power coated steel and heavy gauge galvanized steel.

The majority of configurations have belt-drive blower fans that are encased in weather-resistant cabinets for year-round protection.

Fresh MUA units are available with a variety of hood sizes with air flow rates reaching 100,000 cfm.

Industrial Applications

Industrial grade make-up air units are made of heavy duty galvanized steel or a corrosive duty casing.

Additional features for industrial units are wall seams & roof panels that are interlocked, weather proofed, and casing insulation.

Below are typical examples of industrial make up air units:

Mounting Options

Industrial MUA units offer a variety of mounting possibilities as well as a much larger operating range.

An Industrial Make-Up Air Unit on a rooftop. DX cooling module is attached

Make-Up Air Manufactures

We are authorized distributors for the top-rated make-up air unit manufacturers in the United States. As authorized representatives, we will gladly assist you in determining the best make-up air unit for your application.

Please contact us if you need a quote or have any questions about industrial and commercial MUA.

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Our Mission

We Sell Make Up Air’s goal is to continually supply and distribute industrial & commercial ventilation equipment with fast turn around time and great service.

From product selection to providing installation solutions, we are here for your industrial ventilation needs.

Please take the time and learn more about us.


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