Ever wondered what happens to the air that your kitchen range hood pulls out? When you run a powerful exhaust system, it removes smoke, steam, heat, and odors from your kitchen. But what many homeowners don’t realize is that the air being exhausted needs to be replaced to keep your home comfortable and safe.
That replacement air is called makeup air. As the name implies, makeup air is the fresh, filtered air brought back into your home to “make up” for the air that was removed. Without it, your home can experience negative air pressure, drafts, and even backdrafting from gas appliances.
This leads to an important question: Do you need a makeup air unit for your kitchen range hood? And if so, what are your options? In this article, we’ll break down what makeup air is, why it’s essential for high-performance ventilation, and how to determine if your kitchen setup requires it.
What Is Makeup Air?
Makeup air refers to fresh air brought into a building to "make up" for air that has been exhausted by mechanical systems such as kitchen range hoods, bathroom fans, dryers, or HVAC systems. In simple terms, when your kitchen range hood removes smoky, greasy, or hot air from your cooking area, something needs to replace that air. That "something" is makeup air.
Without a proper makeup air system, your home may experience negative air pressure, leading to unpleasant consequences like backdrafting, poor indoor air quality, and inefficient appliance operation.
When Do You Actually Need a Makeup Air Unit?
Determining whether you need a makeup air unit depends on kitchen size, ventilation quality, regulatory mandates, and usage patterns. Below are four key scenarios to consider:
Compact Kitchens
In small kitchens with limited air volume, even moderate exhaust can quickly drop indoor pressure. Running a high‑capacity range hood (often above 500 CFM) without makeup air may result in drafty conditions, poor hood performance, or discomfort. Installing a make up air system, particularly a make up air unit for kitchen hood, helps maintain stable pressure and ensures the hood operates efficiently.
Homes with Weak Ventilation
Newer homes designed for energy efficiency tend to be tightly sealed and lack natural air exchange. When the range hood exhausts air for extended periods, fresh air must enter somehow. Without a dedicated make up air system, air might be pulled in via HVAC returns or even combustion appliance vents, possibly causing safety or air-quality problems. A dedicated makeup air unit directly brings clean outdoor air and avoids unsafe air paths.
Compliance with Building Codes
Most mechanical codes require that if a kitchen exhaust hood exceeds 400 CFM, a makeup air solution must be in place. This can be either a mechanical makeup air unit or a passive damper system, provided unsealed combustion appliances exist in the home. If all appliances are direct‑vent or sealed, some exceptions allow distilling requirements up to 600 CFM. Regardless, when thresholds are surpassed, a compliant make up air system is mandatory and must operate in sync with the exhaust fan.
Extended Range Hood Operation
Even if your range hood is below the 400 CFM threshold, long-duration usage, such as continuous cooking or extended high-heat work, can gradually depressurize your house, reducing hood effectiveness by up to 30%. A dedicated makeup air unit ensures fresh air supply matches your make up air for range hood needs over long cooking sessions, preserving performance and balance.
Why Is Makeup Air Important?
Makeup air is more than just a ventilation accessory, it’s crucial for the safe and efficient operation of your kitchen and home. Here's why:
1. Prevents Negative Pressure
When too much air is pulled out of your home without adequate replacement, it creates negative pressure. This can cause outdoor air (or worse, flue gases from combustion appliances) to get sucked back inside, a phenomenon called backdrafting.
2. Improves Indoor Air Quality
Replacing stale or smoky kitchen air with fresh outdoor air reduces carbon dioxide levels, cooking odors, and airborne contaminants like PM2.5 particles, especially when paired with an efficient range hood.
3. Ensures Proper Appliance Performance
Many HVAC systems and gas appliances rely on balanced air pressure. Without sufficient make up air, your furnace or water heater may struggle to operate efficiently or safely.
4. May Be Required by Code
In many regions, building codes require a makeup air system when the kitchen hood’s airflow exceeds a certain volume (often 400 CFM or more). Not having one could delay permits or fail inspections.
Alternatives to Makeup Air Units
If you’re assessing whether a make up air unit is right for your budget or kitchen layout, there are a few viable alternatives you can explore. Each choice has implications for airflow, indoor air quality, and compliance, so it’s essential to weigh the pros and cons carefully.
High-Performing Range Hood
Choosing a range hood with exceptional airspeed and capture capability, like the CleaDeep P1 IQV model, can mitigate the need for a makeup air unit for kitchen hoods in certain setups. CleaDeep’s patented IQV (inclined quad‑vortex) technology generates a high airspeed (~13 m/s), capturing smoke and grease almost instantly, even without extremely high CFM ratings. This reduces airflow imbalances and smoke leakage, potentially minimizing negative pressure impacts that otherwise would require makeup air support.
For kitchens where installing or interlocking a makeup air system is impractical or costly, a high-airspeed CleaDeep range hood delivers efficient smoke removal with quieter operation and lower energy use, even in cases where makeup air might otherwise be needed.
Passive Intake Vents
A passive makeup air system uses a dedicated vent or damper that opens when the range hood runs, letting outdoor air flow in naturally to match the exhaust. This simple solution may meet code in certain jurisdictions if the kitchen hood exhaust is capped under the thresholds and no sealed-combustion appliances are involved. It’s cheaper and easier to install than an active system, but airflow control is limited, especially in airtight homes or during high‑demand cooking.
Window Opening During Cooking
For kitchens with intermittent high‑heat cooking, simply cracking a window or opening a wall vent near the stove can help equalize indoor pressure quickly. This is an uncomplicated, low‑cost choice. It’s not automated, lacks filtration, and doesn’t meet most building-code requirements for permanent solutions.
Dedicated DOAS or Rooftop Supply Units
Dedicated Outdoor Air Systems (DOAS) or rooftop supply units can deliver tempered, filtered outdoor air directly to the kitchen. These are more refined than simple passive vents and can handle higher airflow volumes. While more complex and costly than a basic passive solution, DOAS offers better control over temperature, humidity, and air quality
