Make-Up Air
Make-Up Air is required if your kitchen hood is 400 CFM or higher and you have a naturally drafting appliance or fireplace
New homes are built very airtight, so high-capacity exhaust hoods can cause backdrafting in fireplaces, boilers, water heaters, or other naturally drafting appliances. This can allow flue gases and carbon monoxide to enter the home. Providing a source of outside air helps balance pressure and prevent this issue.
Option 1: Automatic Damper
This method uses an outdoor air intake duct with an automatic damper connected to the HVAC system. The damper opens when the kitchen range hood runs, allowing outside air in to replace exhausted air and help maintain balanced indoor pressure.
Option 2: Make-Up Air Unit
An inline fan brings in outside air at a rate similar to the kitchen exhaust output. The air can be filtered and pre-heated before entering the home, helping maintain neutral or slightly positive pressure and reducing backdrafting risks.