Why you need a Make-Up Air System in your New Home

During the process of a new home, especially during the kitchen design phase, questions arise when clients are told that their hood fan choice requires a make-up air system. What is a make-up air system? Why does my hood fan require it? To provide clarity, we will explain why a make-up air system is needed in certain circumstances.

Hood Fans

A kitchen hood fan is an important appliance that removes odors, grease, smoke, and fumes produced by using your cooktop. The hood fan itself does not replace this exhausted air.  To maintain proper air pressure balance, the HVAC (Heating, ventilation, air conditioning) system works together to provide high quality air in your home.


CFM, or Cubic feet per Minute, is the unit of measurement that indicates the rate of air removal from the kitchen to the outside. The greater the CFM, the higher the removal performance of air and aromas from the kitchen. 200 CFM is the rate for a typical hood fan. A hood fan that operates at 300 CFM or lower does not require a make-up air system. If the hood fan’s CFM is greater than 300, then a make-up air system is required to restore the inside air pressure balance.

Make-Up Air System

A make-up air system, located near your furnace, works to bring air back into the home using a motorized damper and an air pressure sensor that controls the flow of outside air into the home. An 8” duct (for 300-600 CFM) or 10” duct (for 600-1000 CFM) is used. The pressure switch, connected directly to the on/off switch on the hood fan, signals to the damper to open and allow air flow from the outside to enter the return air plenum of the furnace. Additionally, due to our climate, an in-line heater and thermostat are installed that will pre-heat the incoming air when the air temperature outdoors is lower than the air temperature indoors.

Homes are now built to very stringent specifications in terms of “air-tightness”.  As a result, without the make-up air kit, a 300CFM+ hood fan can create a negative pressure within your home.  This can lead to your hood fan not operating to capacity, doors that are harder to open or that slam shut, additional pressures on your remaining HVAC equipment, and risk of higher carbon monoxide levels from gas appliances not being vented properly.

The kitchen is known as the heart of the home. As an increasing number of homeowners are wanting to create their desired kitchen, this typically includes larger and higher quality appliances. If you are planning to purchase a large range or cooktop, especially if it exceeds 4 burners or more, buying a hood fan over 300 CFM is highly recommended to properly ventilate your kitchen and home, and in turn, installing a make-up air system for proper ventilation. Phoenix Homes is dedicated to providing a smooth and enjoyable experience, and we hope that this provides clarity and comfort.

Post Categories: Tips


Next Post: Brand new condos in Ottawa south + limited time bonuses on select units!