Makeup Air and Kitchen Exhaust

Every home needs kitchen exhaust to eliminate cooking odors and smoke, promoting a healthier indoor environment by replacing stale air.

As this happens, outdoor air enters through cracks or openings in the home's envelope, a process known as makeup air.

Exhaust Fan

The fan exhausts the amount of air equal to the makeup air.


Sound attenuation silencer for circular ducts. The silencer effectively reduces noise in the duct.

Duct Heater (Optional)

The Makeup Air Heater automatically varies its heat output to deliver air at the temperature set point.

Makeup Air System (MUAS)

The MUAS is a powered, fresh air supply system that’s ideal to balance the outgoing vented air from a 400+ CFM range hood required by the IRC. 

Makeup air systems represent a calculated balance that ensures a controlled environment, code compliance, safety, and energy efficiency.

Christina Gomes
Christina Gomes
Project Engineer

Why Do You Need a Makeup Air System?

If the kitchen exhaust system exhausts more than 400 CFM, the International Residential Code (IRC) requires mechanical or passive systems to provide makeup air back into the home. 

Even if the exhaust system is only capable of removing 350 CFM of air, it is a good idea to have a makeup air system in place to keep the household safe from backdrafting and the temperature regulated. 

Regulations and Factors

Important to know
  • UL507 Requires products undergo many performance tests, construction requirements, and marking regulations to help keep electric fans safe. 

  • International Residential Code (IRC) M1503.6 States that where fuel-burning appliances are present and exhaust systems exceed 400 CFM, makeup air must be provided at a rate equivalent to the exhaust air rate.

  • IRC M1503.6.1 States makeup air must be discharged in the same room the exhaust system is located in or into rooms or duct systems connected to the room containing the exhaust system.

  • IRC M1503.6.2 States that makeup air dampers must either be gravity dampers or electrically operated dampers that automatically opens when the exhaust system operates.

  • Compliance and Efficiency Adhering to codes ensures safety and minimizes costs through energy-efficient solutions.

  • Temperature and Humidity Control Integrating a duct heater in the makeup air system helps temper cold air, minimizing condensation.

  • Customizable The MUAS is adaptable for installation according to the application's needs, allowing for linear or flexible snake-like configurations with sufficient ductwork.

  • Quiet When installing a kitchen exhaust system, placing the fan further away from the kitchen will ensure less noise can be heard during operation. 

  • IAQ Kitchen exhaust, combined with a mechanical makeup air system, maintains balanced indoor air pressure during fan operation, ensuring safe removal of smoke and grease, thus enhancing indoor air quality.

For kitchens equipped with cooking appliances, ensuring makeup air enters the home is essential. While older homes typically rely on natural infiltration to prevent backdrafting, newer, more energy-efficient and air-tight constructions necessitate mechanical or passive methods to maintain balanced air and prevent backdrafting. This requirement applies to remodeled kitchens as well.

What to Know?

How to size the unit?

Match the exhaust fan capability with either the MUAS 750 or the MUAS 1200. If the CFM is 750 or less, use the MUAS 750. If it is more than 750, opt for the MUAS 1200 to match that outgoing air. 

What about exhaust?

The rule of thumb for range hood fan size is “for every 12” of stove width, the exhaust fan must be able to move 100 CFM of air.” 

Do I need a silencer?

The LD silencer reduces the "perceived" noise of a kitchen ventilation system by 50–60%. This is particularly important with range hoods where the airflow rate is generally high (300+ cfm). 


Best practices

Installed in an uninsulated environment?

Yes, however, try to avoid installing the makeup air system and the supply air duct work directly above or less than 2 feet to any furnace or its supply plenum, boiler, water tank or any heat producing appliances. Remember to insulate the ductwork to the R value required for your area.  

What if they have a fireplace?

A makeup air system is safe to operate with a fireplace in use and should be installed to prevent backdrafting. 

Discovery Questions

Good to Know

Can I use a Makeup Air System with multiple exhaust fans?

The MUAS will not replace the air exhausted from any other system besides the kitchen exhaust system. The MUAS is interlocked with the kitchen exhaust system.

What is the best location for an interior register to bring the fresh air into the home?

Fantech suggests installing the supply air register as close to the kitchen exhaust range hood as possible.

Should you use a heater with a MUAS?

If you are in an area that experiences cold weather in the winter time, you will want to have an additional MUAH heater to temper the air coming into your home. 

Can you install a MUAS in a vertical position?

Yes. Due to its component-based, field-assembled nature, the Fantech MUAS offers flexibility in the installation process as far as location and point of orientation are concerned. However, Fantech recommends that the installation location be suitable for periodic inspection and maintenance. The MUAS does not require installing the individual system components in a linear (straight line) arrangement. 

Can the components be installed with a 90 degree bend?

Yes, you can split the components into segments to support tight spaces. Be mindful of the location of the heater when altering the air path through the device. Install the components a minimum of 24 inches before and after the heater to ensure linear airflow across the elements. Non-linear air flow can create pockets of low air that can cause the element to overheat and shorten the elements life.

How often should the filter be changed?

At a minimum, Fantech recommends you inspect the filter every 2–3 months. Once you have a better understanding of how the air quality affects the MUAS over a longer period, you may only have to inspect your filter every 6 months.

Modern, loft style community kitchen

Community Kitchen

Community Kitchens are increasingly popular for larger gatherings in multi-family residential projects. They require powerful exhaust systems and makeup air systems that don't disrupt communal gatherings with noise.

Food Prep Area

Using an exhaust fan to remove cooking odors is an effective method for improving IAQ, but in large kitchens with persistent smells, it can be challenging. A simple solution is to install an exhaust duct connected to an inline fan to effectively eliminate these odors.

Learn from Our Pro


Discover the fundamentals of Fantech's Makeup Air Systems with insights from our expert, Mark Wald. This concise video provides essential information in under one minute.

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