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.
A structure that is in a negative state of pressure is dangerous, unhealthy, and expensive to operate.
Make-Up Air 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.
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
- By eliminating drafts, the crew is more comfortable, which leads to increased production.
- Indoor air quality and pressure are completely within your control.
- For some applications, achieve 100% efficiency.
- Negative pressure inside the structure is properly controlled.
- Reduces the cost of energy
- Puts an end to hazardous carbon monoxide and back-drafting
- Brings the building up to code and with local, state & federal compliance
- Obstructs unconditioned outside air from entering
Features
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:
- Blower Fan
- Cooling and/or Heating Components
- Back-Draft Damper
- Vent
- Filters
This is the basic construction, but certainly not the limitation.
- Multi-Stage Filtration
- UV-C Germicidal Irradiation
- Cabinets that are Insulated
- Double wall
- Recirculation Features
- Variable Volume
- Building Pressure Controls
- High Temperature Discharge
Make Up Air Unit Configurations
There several configurations with a variety of heating and cooling solutions including:
Cooled Make Up Air Units
Heated Make Up Air Units
Heated & Cooled Make Up Air Units
Untempered Make Up Air Units
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:
- A commercial space, such as a large office building, utilizes make up air to pressurize the various floors due to the negative pressure produced by elevator shaft effects and exhaust systems.
- Implemented in warehouses to temper and recirculate air.
- Frequently used in the institutional sector to filter and produce high air exchange rates of clean fresh air.
Mounting Options
Industrial MUA units offer a variety of mounting possibilities as well as a much larger operating range.
- Horizontal Mounting
- Vertical Mounting or Side-Wall Mounting
- Roof Mounting
- Suspension Mounting
- Roof Curb Mounting
- Mezzanine Mounting
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.
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.


AbsolutAire Since 1992, AbsolutAire has been the nation’s top maker of total air management systems and heated, cooled, and ambient replacement air. AbsolutAire applies its


Direct Gas-Fired Make-Up Air Unit Direct gas-fired make up air units consist of burners that are nearly 100% efficient (source) and are suited for applications


Heated Make-Up Air Unit A heated make-up air unit is a mechanical device that is used to introduce heated air into a building or space


Moffitt Ventilation Corporation Overview Table of Contents Authorized Moffitt Suppliers We are the authorized distributors for the leading American manufacturer – Moffitt Corporation. We’ll be
Cooled Make-Up Air Units Authorized MUA Dealers We are the authorized distributors for the leading American manufacturers of cooled makeup air units. We’ll be pleased