Clearing the Air: The Ultimate Guide to Proper Kitchen Ventilation

After 17 years of publishing articles, seven years making videos, and hosting roughly 25 webinars, I’ve come to understand that effective kitchen planning boils down to three essential elements:

• Sink Placement: Your sink should be centrally located to streamline your kitchen tasks.
• Range vs. Cooktop and Wall Oven: It’s crucial to choose the setup that best suits your cooking habits.
• Ventilation: Proper planning here is critical to ensure it works efficiently.

If the first two elements are off, it’s mostly just inconvenient (we dive deeper into these topics in other articles).

However, choosing the wrong ventilation system can be outright unhealthy.

In this article, you'll learn how to properly vent any stove, from a compact 20-inch range in an apartment to a massive 60-inch Wolf professional range with a double griddle.

You’ll discover which vents to avoid and why proper venting has become more important than ever.

This is a must-read.

For even more in-depth insights, be sure to check out our Ventilation Buying Guide.

Let's get started. 

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Clearing the Air: The Ultimate Guide to Proper Kitchen Ventilation

Quick Question: Which burner did you use when you cooked today?

I would probably guess the front right or left burners.

Let's see how that plays out on a popular range with the matching over-the-range microwave.

Have a look at the Café range and over-the-range microwave:

Now look again:

The average microwave is 15-16 inches deep, yet that front right burner is 23 inches deep.

So all that heat, grease, and other pollutants are not fully vented.

Also, the front burner of all ranges is designed to be high output.

But what does that mean?

Let's take cooking bacon as an example to fully understand this concept.

When you cook bacon, for example, you might think it's just the wonderful bacony aroma filling your kitchen (and maybe a bit of unwanted grease).

However, there's more to it. You are also releasing potentially harmful compounds.

Here's a partial list:

• Nitrogen Oxide (NO)
• Nitrogen Dioxide (NO2)
• Carbon Monoxide (CO)
• Formaldehyde (CH2O or HCHO)
• Particulate matter (PM2.5)

Even though induction and electric cooktops emit some of these compounds, the levels are much lower.

Given these risks, you'd think people would take ventilation more seriously.

Then you see these. 

1 A professional high-output range with no rangehood or ventilation.

2 A downdraft behind a professional range. 

3 An island hood over a professional range.

Note: You definitely don't want to add these to your Pinterest profile. Let's break down why that is.. Let's break down why that is. 

Bad Kitchen Ventilation Examples

This AGA professional range has eight burners. Yet, it has no vent - none at all.

Without a vent, this kitchen will trap all that wonderful bacon aroma, along with grease and less-than-wonderful compounds—a truly bad idea.

Another bad idea is downdrafting high-powered burners, especially a grill.

Do you grill outside? Think you can downdraft all that smoke?

You'll learn why downdrafts aren't effective later in the article.

In the next example shown below, the hood isn't designed for a professional range. It lacks one key attribute common to all ineffective vents.

You'll discover more about this further down in the article as well.

Even my Mom's range hood cannot handle the output of her Wolf dual fuel pro range:

She didn't consult me on this purchase.

Let's go back to the Café. By the way, I love their line of appliances, with its ability to customize color and handles.

However, according to their specs, the top of the hood should be no more than 48 inches off the floor.

The hood is 18 inches tall, so its bottom should be 30 inches off the stove.

Does that look like 30 inches?

It's 40-48 inches off the range.

When a hood is too high, some exhaust will remain in your home.

Why You Should Buy the Right Vent for Your Kitchen Range

The Environmental Protection Agency warns that "studies of human exposure to air pollutants indicate that indoor levels of pollutants may be two to five times and occasionally more than 100 than outdoor levels."

In other words, I will be better off eating my lunch next to my office on the Expressway than preparing it without a vent (well, maybe not).

Average Output of a Gas Range (1970s to Present)

The average output of a range when I started at Yale in 1986 was about 37,000 BTU.

Now it's 60,000 BTU. This BlueStar range (shown above) is 80,000 BTU

My Mom's range was about 28,000 BTU. I can't remember her using a vent atop that second oven.

Then again, it wasn't as important due to the lower burner output.

Your Efficient New Home in 2024

LEED certifications, ventless appliances, improved windows, and certain materials can cause pollutants to remain in your home for extended periods. 

The 4 Basics of Venting:

Venting requires exhaust, commonly called CFM, capture area, an acceptable duct run, and size.

CFM

• CFM Explained: Stands for cubic feet per minute, indicating the volume of air evacuated from your house each minute.
• Typical Range: Range hoods typically operate between 350 to 1500 CFM.
• Visualization: A 1500 CFM exhaust can clear the air equivalent to a small room every minute.
• Understanding CFM: Higher CFM values mean more air is expelled, making it a straightforward measure of exhaust effectiveness.

Take a look at this range hood and professional range:

The hood is too high in this installation.

Blowers

I know you, like most people, prefer the hood to be quiet.

Inline or outside should be much quieter, but you will still hear the air rushing through the vent with any of the three types.

Internal is my favorite because it is the simplest to fix.

The outside vent is a larger blower, which may not look the best versus a simple wall cap.

If you need repair, you will need an access point for the inline blower.

How Much CFM Do You Need?

When I was starting, we were taught venting required 1 CFM per 1000 BTU of output.

That's not smart thinking.

The real answer is it depends on how you cook.

You need more for working, grilling, and griddling and less if you use your stove.

For grills, a minimum of 900 CFM or more is adequate. For 48-inch stoves, you should plan on 1200-1500 CFM.

Below are the prices of internal and external blowers

• Internal 600CFM blower (P6) $318.98
• Internal 800CFM (IQ6) $815.98
• Internal 1200 CFM (P12)$499.98
• External 600CFM (EB6) $715.98
• External 900 CFM (EB9) $850.98
• External 1200 CFM (EB12) $1152.98

Regarding the overall cost of planning your kitchen, the difference in cost of an upgraded blower is not that much.

If you cook a lot or tend to burn your food a bit, consider a larger blower.

Remember: Anything over 400 CFM requires make-up air to get your occupancy permit - more about make-up air later.

Now, the element that most bad elements have in common:

Capture Area

• Definition of Capture: Capture refers to the height, width, and depth of your range hood, which are crucial for its effectiveness.
• Location of High Outputs: Typically positioned at the front of the range, high outputs can cause smoke to escape past shallower hoods.
• Minimum Depth Recommendation: If you cook frequently, ensure your hood is at least 24 inches deep.
• Importance of Depth: Adequate depth is vital as it helps contain and exhaust smoke effectively.

Venting Direction

We have been writing the Yale blog for 17 years. The highest number of questions are always about venting.

They always start with: "Is it OK if I do X?"

The answer to that question always seems to be no - unfortunately.

Venting direction is easy.

You want to use gravity and run your venting up and straight out.

If you are on a wall, then straight back is fine.

Venting down, using multiple elbows will never work because the static flow will slow with too many elbows.

Duct Size

• Recommended Duct Size: Always use the rigid duct size recommended for your range hood.
• Rigid Piping: Opt for rigid piping to prevent grease accumulation in flexible joints, which can cause issues later.
• Adherence to Specifications: Stick to the manufacturer’s specifications, or consider a larger size if you cook frequently.

I remember when people used dryer vent kits to vent their stoves.

Four-inch cloth to house all that grease.

Surprisingly, more fires weren't started.

How to Vent an Island

Venting an island is similar to a wall hood.

The vent is installed at the top rather than the back.

You may want a larger hood because the wall doesn't channel the smoke.

Venting Products to Avoid

Below are some ventilation products to avoid if possible:

• Downdrafts
• Slide-Out Hoods
• Over-the-Range Microwaves
• Wood Range Hoods

Disclaimer: Sometimes, you might have no choice but to use these options. If so, try to make sure they work as well as they can

Downdrafts

Downdrafts were popular in the 1980s, so people could feel good about placing the cooking on an island.

You can see the windows better.

However, it doesn't work without a capture area and a longer duct run with an elbow to reduce the exhaust.

Placing your sink in the middle of your island is a much better solution.

Over-the-Range Microwaves

I had an over-the-range microwave when I moved to an apartment last year.

I remember the steam blowing past it when I was making tea.

At an average of 15.5 inches, how effective can the burners be at 23 inches?

Slide-Out Hoods

For the few designers and architects still thinking a glass visor is cool, it isn't.

A flat sheet of glass is incapable of venting properly.

Custom Hood Inserts

Wood or custom hoods are a great way to distinguish your kitchen.

You are buying a liner or metal box to hold the blower. Then, you buy the blower with the filters, lights, and controls.

So, imagine taking a Sawzall and cutting the motor out of a regular hood.

That's what you are doing with a wood/custom hood.

Many people make the mistake of buying an underpowered blower, not planning the right capture, or hanging it too high.

I am not sure these work well. I have to figure out how to test them.

I used to live in Cambridge, and the owner placed a bath fan over the range.

It worked, but there was grease all around the front as well.

Ceiling Blowers

Ceiling blowers are better than downdrafts but read the installation specs.

You cannot place them too high like the one pictured.

Make-Up Air

Make-up air is the law in Massachusetts, and for good reason.

Let's say you buy a powerful vent of 1200 CFM.

That's 1200 cubes of Air exhausting out of your house per minute, or the rough equivalent of a small room  - per minute.

Let's say you don't have fresh air and return to your kitchen.

No you won’t asphyxiate.

That air will comprise your furnace, attic, garage, and basement.

The simplest way is to install a fresh air return through your HVAC.

Look in the diagram above.

The code also stipulates that you should be ten feet away from the range on the opposite side so you don't breathe the stove exhaust.

Ventless Options

I am not a fan of ventless options. Depending on the vent, it is better than nothing, but gasses will not be filtered, just the odors.

However, you should opt for a triangular European-style hood.

The air won't be recirculated directly at your face.

For Bad Ventilation Situations

First, this article is not about spending $30,000 because you are too alarmed at replacing an existing downdraft in your kitchen.

That's too alarmist.

Instead, let's focus on everyday solutions:

• Turn on your vent. Most people buy a decent vent but don't turn it on.
• If your vent is bad, like a downdraft or over-the-range microwave, buy induction or electric for less emission.
• Cook on the back burners.
• Open your windows. Need a fresh air return? Opening a window is the very definition.
• Air cleaners can be helpful. However, HEPA only filters to .3 of a micron, so you will need a combination of HEPA and charcoal to filter some gases. I use a Sharp Plasmacluster in my kitchen.

The Ultimate Guide to Proper Kitchen Ventilation: Key Takeaways

It's not that difficult.

Assess what you need for CFM. Buy a hood that covers the front burners you use and vent straight up and back.

In other words, avoid most of the vents sold in an appliance store.

Also, make-up air is the law in Massachusetts, so plan a fresh air return in your kitchen.

Additional Resources

Get the Yale Ventilation Buying Guide with features, specs, and inside tips for every brand and hood type. Well over 1 million people have read a Yale Guide.

Related Articles:

• Best Ventilation Hoods for Professional Ranges
• How High Do You Hang a Range Hood?
• Can You Place a 600 CFM Hood Over a Professional Rangetop?
• Can You Replace a Range Hood With a Microwave Vent/Hood?