WHAT IS MAKE-UP AIR?

Make-up air is outdoor air supplied to a building to replace air removed by exhaust fans, industrial processes, and other ventilation systems. A make-up air unit (MUA) draws in outdoor air and can heat, filter, or otherwise condition it before delivering it into the building.

Make-up air systems are commonly used in commercial and industrial buildings where exhaust equipment removes significant amounts of indoor air. By supplying replacement air, these systems help manage building pressure, support effective ventilation, and maintain more comfortable indoor temperatures.

How Does a Make-Up Air Unit Work?

A make-up air unit brings outdoor air into a building to replace air removed by exhaust systems. In a typical MUA HVAC application, the process works as follows:
1. Outdoor air enters the unit. The make-up air unit draws outdoor air through an inlet or rain hood.
2. The air is filtered or conditioned. Depending on the configuration, the MUA system can include filtration and other air-treatment options.
3. The air is heated or cooled. The Cambridge M-Series can provide tempered make-up air for applications requiring heating, with optional cooling configurations available.
4. Conditioned air enters the building. The unit delivers the conditioned outdoor air through the selected discharge configuration.
5. The incoming air replaces exhausted air. This helps compensate for air removed by building exhaust systems.

WHAT PROBLEMS CAN MAKE-UP AIR SOLVE?

Standard make-up air units are designed to provide a building with tempered fresh air, both heated and cooled, to offset air that is exhausted by other mechanical means. When exhaust fans or industrial processes remove air from a building without an adequate supply of replacement air, the building can become negatively pressurized. This pressure imbalance may cause outdoor air to enter through doors, cracks, and other openings, creating drafts and temperature fluctuations.

Insufficient make-up air can also make it harder for exhaust systems to operate as intended. In some buildings, it may contribute to doors that are difficult to open, uneven airflow, or discomfort for employees.

A properly designed make-up air system can help address several common building challenges:
• Negative building pressure: Supplies replacement air to help balance the air removed by exhaust systems.
• Uncomfortable indoor temperatures: Tempers incoming outdoor air to reduce the impact of extreme outdoor temperatures.
• Ventilation challenges: Supports planned outdoor-air delivery in facilities with substantial exhaust requirements.
• Indoor air quality (IAQ): Helps support a broader ventilation strategy by supplying outdoor air to replace exhausted air. IAQ also depends on effective contaminant removal, air distribution, filtration where appropriate, and other building-specific factors.
• Excessive drafts and uncontrolled infiltration: Can reduce reliance on outdoor air entering through unintended openings when the system is properly designed and balanced.

Think a Make-Up Air System Makes Sense for your Facility?

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COMMERCIAL & INDUSTRIAL MAKE-UP AIR APPLICATIONS

VENTILATING WAREHOUSES AND DISTRIBUTION CENTERS

High-bay buildings are some of the easiest types of structures to work with when implementing a make-up air solution. For a high-bay warehouse or distribution center to meet the ASHRAE 62.1 standard and local building codes, the natural infiltration rate of the building is often enough to satisfy the fresh-air requirements during occupied hours. As building envelopes become tighter and more efficient, these buildings may need mechanical ventilation to meet local codes.

But the ventilation considerations do not end there.

Regardless of whether your building relies on natural infiltration or mechanical ventilation, both methods require you to address the temperature of the outdoor air entering the building.

While simple ventilation fans can help provide fresh, comfortable IAQ in buildings in more temperate climates, using unconditioned outdoor air to ventilate a building located in a region with cold winters or hot summers can create uncomfortable temperatures for the workforce. Make-up air systems are ideal for tempering the outside air to improve the comfort and safety of those inside.

Make-up air may be especially important in facilities with:
• Industrial process exhaust
• Large exhaust fans
• Manufacturing equipment
• Welding or fabrication processes
• Commercial kitchens
• Warehouses and distribution facilities
• Production facilities
• Large industrial spaces with ventilation requirements

Industrial & Commercial Make-Up Air - Cambridge Air Solutions

SPECIAL CONSIDERATION FOR INDUSTRIAL FACILITIES

Ventilation factors move to an entirely different level when considering industrial facilities. From pharmaceutical manufacturing plants to auto assembly plants to even wastewater and sewage treatment facilities, industrial environments of all sorts have different processes happening inside. These factors dictate the type and amount of mechanical ventilation needed to meet IAQ standards.

Even though these structures experience infiltration of outside air just like a warehouse, the amount of incoming air will not match the amount of mechanical exhaust that an industrial plant has in place to ventilate the facility.

Industrial facilities require an in-depth study on the amount of exhaust cubic feet per minute (CFM) and the location of the exhaust fans to understand the make-up air options for replenishing the air, while maintaining a neutral pressurization, high IAQ and comfortable working temperatures.

DIFFERENCES BETWEEN MAKE-UP AIR AND STANDARD VENTILATION

A make-up air unit is specifically designed to introduce and condition outdoor air to replace air exhausted from a building. Standard ventilation fans bring in the outside air “as is” without heating or tempering. If the outside temperature is 100° F with 85% relative humidity, then a standard ventilation fan is bringing in 100° F with 85% relative humidity air. Likewise, if the outside air temperature is -10° F, then the ventilation fan is bringing in -10° F air.

With a make-up air unit, that same -10° F air can be tempered to 50° F. This means the heating system wouldn’t be required to work any harder than is necessary nor would it waste energy.

LEARN ABOUT THE CAMBRIDGE® M-SERIES MAKE-UP AIR SOLUTION

Cambridge Air Solutions provides commercial and industrial make-up air solutions designed for demanding applications. The Cambridge M-Series make-up air units are designed to deliver tempered make-up air for a wide range of commercial and industrial facilities.

M-Series' products features include patented Low-Fire Start Technology, proprietary stainless-steel burners, and multiple configuration options to suit different facility requirements. Depending on the application, options can include variable frequency drive (VFD) control, filtration, different discharge arrangements, and cooling configurations.

The M-Series can be incorporated into new construction, plant expansions, renovations, HVAC upgrades, and industrial retrofit projects.

Contact us today to speak with one of our experts to learn more and discuss your project in detail.

Cambridge Air Solutions M-Series - Make-Up Air Unit

Air Solutions Tour

Cambridge's Air Solutions Tours are customized to answer your questions regarding how our make-up air technology can help you address your facility's air quality and ventilation challenges. Your knowledgeable Cambridge guide will walk you and your team through our facility and answer any specific questions you may have regarding make-up air solutions such as the M-Series for industrial and commercial applications. If you have questions about our Air Solutions Tours, get in touch with our Sales Development Representative by phone or chat. Schedule an in-person or virtual tour today!

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