Imagine a range hood acting like a giant straw. It pulls cubic feet of air outside every minute. Where does that exhausted air come from?
Without balanced flow, your house develops negative pressure, dragging cold outside air through cracks and even reversing combustion appliances. Today I explain what is make up air for range hood systems, show you proven fixes, and promise a safer, fresher kitchen.
Keynote: What Is Make Up Air for Range Hood?
Make-up air replaces kitchen air your range hood expels. When hoods exceed 400 CFM, codes require balanced intake to stop negative pressure that can backdraft gas appliances, pull in pollutants, and strain HVAC. Dedicated ducted systems supply filtered, tempered outdoor air, keeping cooking efficient, indoor air safe, and comfort stable.
What Is Make-Up Air? (And Why Your Home Can’t Live Without It)
Make-up air is simply fresh air that replaces the exhaust air your kitchen range hood removes. Picture a sealed juice box. Sip hard with no vent hole and the box collapses. Your kitchen behaves the same.
Low indoor air pressure triggers three big problems. First, backdrafting from gas appliances like a water heater can pull carbon monoxide inside. Second, doors stick because the house sucks inward. Third, indoor air quality drops; smoke, grease, and smells linger.
Balanced kitchen ventilation systems stop those headaches by adding the same amount of outdoor air the exhaust fan removes.
How Range Hoods Impact Your Home’s Airflow
A hood’s power is its CFM rating, cubic feet per minute. A 600 CFM hood ejects 600 cubic feet of air each minute. Most building codes demand makeup air when a hood exceeds 400 CFM because the pressure loss grows fast.
High-CFM hoods without supply air cause:
- Less effective vent hood capture; smoke escapes.
- Extra load on the HVAC system and air handler.
- Uneven temperatures, especially in small kitchens or a small space with few leaks.
IRC MUA Requirement Summary (2018/2021 IRC M1503.6)
| Range Hood Exhaust Capacity | Presence of Non-Direct-Vent / Non-Mechanical-Draft Combustion Appliances within Air Barrier? | IRC MUA Required? |
|---|---|---|
| ≤400 CFM | No | No |
| ≤400 CFM | Yes | No |
| >400 CFM | No | No* |
| >400 CFM | Yes | Yes |
*Always confirm local code requirements and the International Residential Code with your inspector.
Do You Need a Make-Up Air System?
Ask four quick questions:
- Does the CFM of your range hood exceed 400?
- Is the house tightly sealed (spray foam, triple-pane)?
- Do you run a gas range, dryer exhaust, or bath fans for long periods of time?
- Have you noticed whistling, sudden drafts, or lingering cooking odors?
If you answered yes to any, a makeup air system is a good idea. Opening a window delivers less air than the hood expels, especially during winter or long periods of time at high speed.
Types of Make-Up Air Systems: Passive vs Active
Passive systems
A damper in an air duct opens when the exhaust system starts. The hood’s suction pulls outside air through the air intake. Simple, cheap, but flow varies with fan speed and duct length.
Active systems
An inline air unit with a blower pushes clean air inside. Some models include an optional heater to temper cold air—a better option for cold climates and big cfm vent hood setups.
Feature Comparison
| Feature | Passive System | Active System |
|---|---|---|
| Cost | Lower | Higher |
| Maintenance | Low | Moderate |
| Climate Suitability | Mild | All climates |
| Installation Complexity | Simple | Complex |
Comparison of Residential MUA System Types
| System Type | Key Components | Airflow Mechanism | Pros | Cons | Typical Use Case |
|---|---|---|---|---|---|
| Passive | Damper | Negative Pressure | Simplicity, Lower Initial Cost | Less Control, Climate Sensitivity, Potential Inadequacy | Milder Climates, Lower CFM Hoods (<600), Budget Projects |
| Active (Untempered) | Damper, Fan, (Filter) | Fan Driven | Control, Reliability, Filter Option | Higher Cost, Fan Energy/Noise, Climate Sensitivity | Tight Homes, Higher CFM Hoods, Moderate Climates |
| Active (Tempered/Heated) | Damper, Fan, Heater, (Filter) | Fan Driven | Comfort in Cold, Reduced HVAC Shock | Highest Cost, Heater Energy Use | Cold Climates, High-Comfort, Bigger Budgets |
User Perspective Table
| Type | Description | Example Use Case |
|---|---|---|
| Passive | Relies on pressure and a damper. | 400 CFM hood in a moderately tight house. |
| Active | Fan adds measured supply air; may filter or heat. | 1 200 CFM hood in a high-performance home. |
Active systems shine in airtight houses because the blower matches the exhaust air rate minute by minute.
Designing an Effective Make-Up Air System
- Intake placement: Ten feet from chimneys, dryer exhaust, or garages to keep air quality high.
- Split flow—60 % to the kitchen, 40 % to nearby rooms—reduces grease spread.
- Insulate duct work to block condensation.
- Wire a pressure sensor or current switch so the damper opens only when the range hood exhaust runs.
- In cold zones, add a small rooftop unit or inline heater to warm the incoming blast.
Ignoring these steps can disrupt kitchen hood capture and waste hot water energy by chilling the room.
Costs, Installation, and Expert Tips
- Passive kits: $500–$1 000 plus basic air duct materials.
- Active untempered: $1 500–$2 500, including blower and filter.
- Active tempered: $2 500–$3 000+ for the heater and extra wiring.
DIYers can tackle passive setups in small space projects. Hire an HVAC pro for active units; balancing cubic feet of air with the hood and adjusting the air handler takes experience.
Pair the range hood makeup air system with an ERV to recycle energy and boost indoor air quality. Some manufacturers package everything as a powered MUAS kit for hoods over 400 CFM.
Conclusion: Breathe Easy with Balanced Ventilation
Understanding what is make up air for range hood protection turns a smoky, drafty kitchen into a safe, enjoyable workspace. Balanced kitchen ventilation safeguards health, equipment, and energy bills.
Audit your hood’s CFM, confirm local rules, and size a makeup air intake before your next stir-fry. Balanced air isn’t a luxury; it’s a quiet guardian of clean air and comfort you’ll appreciate every meal.
Make up Air for Range Hood (FAQs)
Can my existing HVAC provide make-up air?
No. The HVAC system is sized for steady loads, not sudden 1 000 CFM gusts.
Do all-electric homes need it?
Yes if the cfm range hood is high. You still risk drafts and poor air quality.
Will bills skyrocket?
Minimal. A tuned active system uses small fans and, if heated, runs only while cooking.
Katie Lee has over 20 years of experience in the kitchen. She helps homeowners find the right appliances for their needs to sets up a perfect kitchen system. She also shares helpful tips and tricks for optimizing appliance performance.