How a Makeup Air Unit (MAU) Works

A Makeup Air Unit (MAU) operates by drawing in outside air, conditioning it (heating or cooling as needed), and then distributing it throughout a building. This process replaces air that has been exhausted by fans or other ventilation systems, helping to maintain proper airflow and prevent negative pressure.

Components and Operation of an MAU

1. Air Intake

The MAU begins by drawing in fresh outside air through an intake. A backdraft damper is often included to prevent reverse airflow when the unit is not operating.

2. Filtration

The incoming air passes through filters that remove dust, pollen, and other contaminants, ensuring that only clean air is introduced into the indoor environment.

3. Conditioning

The filtered air is heated or cooled as needed, depending on the season and the specific requirements of the building. This is achieved using heating coils, cooling coils, or other conditioning elements.

4. Distribution

Once conditioned, the air is distributed throughout the building via ductwork and registers, effectively replacing the exhausted air and maintaining balanced pressure.

Why Are MAUs Important?

• Prevents Negative Pressure
  • Replaces exhausted air to equalize indoor pressure
  • Prevents issues like drafts, door slamming, and infiltration
• Improves Indoor Air Quality
  • Supplies fresh, filtered air
  • Helps dilute indoor pollutants and allergens
• Controls Odors
  • Maintains balanced airflow
  • Prevents odors from migrating between building areas
• Maintains Building Envelope Integrity
  • Offsets air loss to prevent uncontrolled air infiltration
  • Supports energy efficiency by stabilizing indoor conditions
• Supports Proper Combustion
  • Provides combustion air for fuel-burning appliances
  • Ensures safe and efficient operation of equipment