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What Is Makeup-Air Fan?

Make-up fan is designed to “make up” the air in your interior space that has been removed due to process exhaust fans. This type of HVAC solution pulls in fresh, tempered air from outside your building to replace existing air that cannot be recirculated.


A make-up air solution is recommended for buildings where environmental conditions requires a greater need for ventilation not only to improve the quality of air within the building, but also protect the health of those inside.

What Problems Can Makeup-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 the space in a home or building is ventilated and not replenished from another air source, the result is depressurization. Consequently, air from the outside will seep through drafty homes and buildings, or if the space is sealed tight ventilation systems will have difficulty exhausting the air.


Reaching high Indoor Air Quality (IAQ) is the main driver behind the need for make-up air units. Whether it is the removal of contaminants in the air or providing a comfortable temperature, there are many ways to improve IAQ. In most industrial and commercial applications, a make-up air solution is a much more effective method compared to typical ventilation fans at reaching an IAQ that greatly improves the safety and comfort of those inside while also not affecting energy efficiency.

Differences Between Makeup-Air And Standard Ventilation


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.


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.


Here at Stable Temp HVAC we know everything about Make-Up Fans, and happy to provide commercial building owners and business owners with information on how to improve indoor air quality and comfort of people occupying the building.

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