Range hoods do a great job of removing smoke, heat, grease, and odors from your kitchen. Maintaining high indoor air quality while cooking dinner for your family is only possible with the right hood and a reliable exhaust fan.
But what about all the air that is pulled out of your home by the kitchen exhaust system? It has to be replaced, especially in modern homes that are sealed tightly.
The answer is makeup air, and we'll dive deep into this important topic below.
What is Make-Up Air?
Make-up air is fresh air brought into your home to replace the air pulled out by the ventilation system. Negative air pressure can quickly build up in your home if you use a powerful range hood without a make up air system in place.
This negative pressure can cause a number of problems. Specifically, it will force air to come into the home from a variety of unintended places -
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Around windows and doors
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From crawl spaces or garages
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Down chimneys
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Through attic gaps
High powered range hoods move a lot of air in a short time. If you don't supply the make up air required through a dedicated system, that air will force its way back in through little gaps and cracks. This leads to drafts and uncomfortable conditions in the home, so it's better to confront the problem head-on by bringing in outside air in a controlled manner.
Why Make Up Air Systems Are Critical in Modern Homes
Older homes were rather "leaky." There were plenty of small gaps in the construction that allowed air to move in and out with ease. This wasn't great news for comfort or energy efficiency, but it did mean that makeup air wasn't really necessary.
Times have changed. With stricter building codes, better materials, and more focus on efficiency, most homes today are sealed up tightly. Incoming air doesn't have a bunch of gaps and cracks to use, so a powerful kitchen range hood needs makeup air to balance things out.
What Happens Without Make-Up Air?
You can run into a number of problems if you use high powered range hoods without a makeup air unit in place. Some of those issues include the following -
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Doors slamming shut when the hood turns on
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Whistling noises made by air sneaking through small cracks
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Fireplace smoke coming back down the chimney and into the house
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Reduced hood performance as the blower fights negative pressure
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Strain placed on your HVAC system
In many places, building codes require you to install make up air with a range hood CFM over 400. This might seem like a hassle, but it's in your best interest to have the system designed properly from the start so negative air pressure issues don't plague your home every time you run the hood.
How Make-Up Air Systems Work
Outdoor air is introduced to the home through a variety of methods with make-up air systems. Here are three common types you may want to consider.
Passive Systems
The simplest solution is a passive makeup air system. With this design, a damper will open automatically when negative pressure is in place. That allows outside air to flow in naturally and balance things out.
While this approach does provide relatively balanced airflow, it has drawbacks. Specifically, the air is not conditioned, so if it's particularly cold or hot outside, it might be hard to maintain comfort in the kitchen.
Motorized Systems
This is a step up from the passive system and will allow your exhaust hood to perform reliably. Instead of a damper that opens once negative air pressure builds up, the damper in this system is wired to the range hood.
That means the damper will open automatically when the hood turns on. You still don't have conditioned air coming into the house, but a motorized damper will reliably keep air pressure balanced.
Conditioned Make-Up Air
A conditioned makeup air system is ideal. As your hood runs, the makeup air that enters will be heated or cooled based on conditions outside. This means not only will your kitchen be more comfortable, but your HVAC system won't have to work as hard while you cook.
Conditioned makeup air is particularly important for big kitchens with more ventilation. If you have a large range hood and a powerful blower moving a lot of air, the volume of makeup air returning will be significant. And, without conditioning, that air could quickly make your kitchen hotter or colder than you'd like it to be.
Considering the Local Climate
Your choice of makeup air unit will depend to some degree on your local climate. Those in a mild climate may be comfortable with using untreated air, but in particularly hot, cold, or humid places, conditioned makeup air is nearly a necessity.
Imagine running a range hood in Minnesota during the middle of winter. Unconditioned makeup air coming from outside would be frigid, and your furnace would struggle to warm the house back up.
Similar problems can be faced in hot and humid climates. Running your range hood in August in Atlanta would mean bringing steamy air into the house and cancelling out all the hard work your air conditioner has been doing. If you live anywhere with extreme temperatures, either hot or cold, investing in conditioned makeup air is smart.
A Make Up Air Unit Can Improve Noise Levels
Properly accounting for makeup air can help with range hood noise levels, as well. If negative air pressure builds up, the blower will have to work harder, and it will be louder as a result.
Balancing air pressure through makeup air reduces strain on the motor. There is lower turbulence in the ducts and less vibration from the blower. That means the whole system runs quieter and you can better enjoy your time in the kitchen.
Seeing the Big Picture
It's important to understand make up air for range hood requirements early in the planning process. Knowing if you will need to install make up air, and knowing what that system will look like, makes it easier to bring the whole project together.
But don't lose sight of the bigger picture while focusing on your makeup air unit. You'll also need to find a beautiful new range hood equipped with the right blower for your kitchen's needs. To get started, explore the stunning metal hoods we offer here at CopperSmith®, or contact us to ask any questions.
