Richard Trethewey does it again with a wonderful explanation of make-up air and why controlling it is so important in your home. In his signature style, he breaks down a concept that’s often overlooked—but crucial for maintaining safe and healthy indoor air.
Modern homes are built to be airtight for energy efficiency—but this can create unexpected ventilation problems. One of the most important solutions is make-up air. If you’ve ever wondered why your range hood or bathroom fan isn’t working as well as it should, the lack of fresh replacement air could be the culprit. In this article, we’ll break down what it is, how it works, and why it’s essential for your home’s air quality.
What Is Make-Up Air?
Make-up air is fresh, outside air that is brought into your home to replace the air being removed by exhaust fans, range hoods, dryers, or furnaces. Without this balance, negative air pressure can develop, making it difficult for your home’s ventilation systems to function properly and potentially pulling in unwanted air from attics, garages, or crawl spaces.
Why It Matters
When a powerful kitchen range hood or multiple exhaust fans are in use, they can remove large volumes of indoor air. If this air isn’t replaced with a controlled source, it creates a vacuum-like effect. This imbalance in air pressure can result in:
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Backdrafting of combustion appliances (a safety hazard)
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Inefficient or underperforming exhaust systems
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Drafts and cold spots throughout the home
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Poor indoor air quality
A properly designed ventilation system ensures these issues don’t occur—keeping your home comfortable, healthy, and safe.
How a Make-Up Air System Works
A make-up air is usually connected to your HVAC system or installed independently. When your exhaust fan or range hood activates, the system detects the pressure change and draws in filtered, and sometimes pre-conditioned, air from outside. This helps maintain balanced air pressure inside the home, especially during cooking or showering when exhaust rates are higher.
When Is Make-Up Air It Required?
In many municipalities, building codes require make-up air systems for kitchen range hoods with airflow rates of 400 CFM or more. Even if not required by local code, it is highly recommended for larger homes, tightly sealed homes, or those with multiple exhaust systems operating simultaneously.
Conclusion
It’s not just a technical detail—it’s a key component of your home’s air quality and safety. Whether you’re building new or upgrading your ventilation system, it’s worth discussing your options with a qualified HVAC professional. The right system can dramatically improve how your home functions and feels.
Let’s Talk About Your Project
If you have a project in mind and would like to discuss ventilation or energy efficiency, don’t hesitate to get in touch. We’re happy to answer your questions and help you make informed choices for your home.
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