What Is Makeup Air? Do I Need It?

Do I Need a Makeup Air Unit?

Makeup air units are typically used to achieve high indoor air quality. They are commonly used in industrial and commercial settings to improve indoor air quality and maintain energy efficiency. However, some situations warrant the use of makeup air units in a residential space.

There are a few scenarios that may require the use of a makeup air unit:

✦ Small kitchens

✦ Poorly ventilated kitchens

✦ Building codes requirements

✦ Long durations of range hood use

Small Kitchens

Makeup air units are beneficial in small kitchens because there is little cubic feet of air present. If you run your range hoods in a small space or don’t have a well-performing range hood, you may begin to notice problems with negative air pressure.

Basically, negative air pressure means that the air pressure inside your home is lower than the air outside. This difference in pressure can cause exterior air to seep into your home. Your range hood or exhaust fan needs positive air pressure to work properly. If your pressure is negative, it will be difficult for the range hood to extract air and perform at its optimal state.

If you’re noticing inward-facing doors opening quickly or your doors are hard to open, you may have negative air pressure. You may also hear whistling or crackling sounds. Also, keep a lookout for rising energy bills, a taxed HAV system, and air drafts. These are all signs that your kitchen could benefit from a makeup air unit.

Poor ventilation

Generally, makeup air units are best for homes that need more ventilation to improve air quality and prevent depressurization.

When using a range hood or exhaust fan, you always want to circulate clean air back into your home. If you have an issue with ventilation and don’t have a makeup unit, the air will be pulled from other sources such as your HVAC system, water heater, or chimney. These sources won’t provide proper circulation and aren’t designed for this purpose.

If you have negative pressure, your kitchen range hood will not work at its optimal state. When the exterior pressure is greater than the interior pressure, the interior air pushes back as the exterior air is trying to go in. As a result, the range hood needs more power to extract the air. But as the amount of pressure between the interior and exterior widens, the range hood can no longer move air out.

You may notice that your air feels musty or heavy. You may also experience negative air pressure and changing temperatures throughout your home. A makeup air unit can help address these issues.

Building Codes

Local building codes may require the use of a makeup air unit based on the CFM of your range hood. Be sure to check into local requirements if you’re planning to purchase a new range hood. They may require a makeup air unit for range hoods with CFM above 500. These codes are most likely to apply to townhouses, apartments, and condos.

In this instance, there isn’t really an alternative if you want to meet code requirements. The only other option would be to select a range hood with CFM under the maximum amount stated by code.

Long Durations of Range Hood Use

Broadly speaking, the longer you run your range hood, the more air will be removed from your kitchen. You may run it for long periods of time if you’re cooking a great deal or at high temperatures. No matter the reason, when the range hood is run for a long time, the air inside the kitchen will be removed and not replaced.

Regardless of the CFM of your range hood, you’ll likely need a makeup air unit if you want to keep your range hood on for hours at a time.

Alternatives to Makeup Air Units

There are some alternative options if you want to improve the air pressure in your kitchen but don’t want to use a makeup air unit. Depending on your kitchen, one of the following solutions may work.

Kitchen expansion

If your kitchen is small (under 70 square feet), expanding it can help to improve airflow. Smaller kitchens have less air in them. If you can increase the footprint of your kitchen, you can increase the amount of air and potentially avoid issues with negative air pressure.

Install a better-performing range hood

As an alternative to installing a makeup air unit, you can select a better-performing range hood and run it on a higher setting for a shorter period of time. Learn more about selecting the right range hood for your kitchen in our range hood buyer’s guide.

Open a window

To quickly and easily depressurize your kitchen, open a window or two near the range hood. By doing so, you’ll equalize the air pressure between the interior and exterior spaces. You can also consider installing additional fans and an air filter.

For more tips on how to keep your home comfortable, stay tuned to the Hauslane blog.