The Benefits of
Make-Up Air Systems for Kitchens
A well-ventilated kitchen is essential for safety, comfort, and air quality. Whether in a commercial setting or a high-powered residential kitchen, ventilation systems work tirelessly to remove smoke, odors, and heat. But have you ever considered what happens to the air that gets exhausted? That’s where a make-up air system (MUA) comes in.
A well-ventilated kitchen is essential for safety, comfort, and air quality. Whether in a commercial setting or a high-powered residential kitchen, ventilation systems work tirelessly to remove smoke, odors, and heat. But have you ever considered what happens to the air that gets exhausted? That’s where a make-up air system (MUA) comes in.
What Is a Make-Up Air System?
A make-up air system is designed to replace the air removed by kitchen exhaust hoods. When a powerful range hood pulls out large volumes of air, it creates negative pressure in the kitchen and surrounding spaces. If there’s no adequate source of replacement air, this pressure imbalance can cause problems, such as:
- Difficulty in opening doors due to suction
- Backdrafting of combustion appliances, which can cause the production of carbon monoxide in the home
- Reduced efficiency and performance of the exhaust system
- Poor indoor air quality, and uneven heating or cooling
Make-up air systems introduce fresh, sometimes conditioned air to balance the loss caused by exhaust fans, preventing these issues and ensuring proper ventilation. While small residential kitchens with low-CFM range hoods (under 400 CFM) may not require make-up air, many situations demand it.
For instance, building codes require a make-up air system in high-powered residential kitchens with range hoods that exceed 400 CFM. Also many modern, energy-efficient homes are more airtight, making it harder for air to naturally replace what’s exhausted.
How Does a Make-Up Air System Work?
A make-up air system consists of an air intake unit that brings in outdoor air and can be filtered and temperature conditioned. The purpose of this induced outside air is to maintain balanced building pressure. Here’s a step-by-step look at how it works:
- Exhaust System Activates – When the range hood is turned on, it begins pulling air out of the kitchen and depressurizes the building.
- Negative Pressure Develops – Any air that is sucked out of the house must be replaced with outside air. This is true for bathroom exhaust, cloth dryers, fireplaces and kitchen exhaust. If the building is too tight the exhaust or vent will not function properly. Think of sucking on a straw with your finger on the end, no hole, no air. Typically, the source of outside air (make air) comes in through leaks in the building such as recessed lights, doors/windows, fireplaces or combustion equipment flues for water heaters or furnaces. None of these places are ideal and some are dangerous.
- Make-Up Air System Engages – New homes are built too tight for large kitchen hoods to get their make up air through natural ventilation (building leaks). The makeup air strategy we like the best is a system Fantech offers. It works like this, when the kitchen exhaust is turned on, a current sensing relay engages the make-up system. The relay sends a signal back to the makeup air control that opens an electronic outside air damper, starts a variable speed inline fan and turns an inline optional heater on if needed. The control also varies the speed of the inline fan based on the speed of the exhaust fan and modulates the heater based on the outside air temperature. We typically introduce this air into the return of an HVAC system so that it can help condition and filter the air. The last touch is to use a whole house dehumidifier. In the summer you are pumping raw outside air and you want to have the ability to recover after the cooking is done.
Key Benefits of a Make-Up Air System
- Prevents Back Drafting – Protects against dangerous fumes from gas appliances or fireplaces from being drawn back into the home.
- Improves Indoor Air Quality – Ensures a constant supply of fresh filtered air and ensures the exhaust hood performs as designed.
- Meets Building Codes – Many jurisdictions require make-up air systems for high-CFM exhaust hoods.
A make-up air system is an essential but often overlooked component of kitchen ventilation. Whether you’re designing a new kitchen or upgrading an existing one, ensuring proper air balance will enhance performance, comfort, and safety.