very interesting articles on CFM and makeup air; 250 cfm suffices

scrappy25May 29, 2013

In my search for information on makeup air requirements in Maryland I found this very interesting article on "green building advisor" which seems to be against the norm here on gardenweb for large and powerful ventilation systems. Obviously this article is intended for the usual kitchen and not those fiery Wolf type gas ranges.The author describes his difficulty in getting information on MUA installation from GE and concludes that 250 cfm is sufficient for most residential kitchens. I'm interested in what the kitchen designers and semi-pros (including self taught ones) think of this article.

I linked the mail one below but here are two other related articles from the same website.

http://www.greenbuildingadvisor.com/blogs/dept/green-building-curmudgeon/why-range-hoods-don-t-work

http://www.greenbuildingadvisor.com/blogs/dept/qa-spotlight/dealing-high-capacity-range-hood

Don't throw stones, i am not affiliated with this company, just earnestly seeking advice on this confusing and seemingly controversial subject.

Here is a link that might be useful: Makeup air discussion

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rovo

Unfortunately, I can't help you with an expert opinion but wanted to say that I share your pain! I tried forever to figure out the MUA requirements for my municipality and spoke to all the local experts, who acted like they had never pondered the question and thought I was nuts. In the end, I found the same article you linked and realized that for our meager needs, 250 CFM was probably ok. I'm sure some will disagree, and many here have far more powerful range hood requirements, so I think the best you can do is use your best judgement given your unique circumstances. I'll just keep opening that window as usual and powering up my standard grade vent hood!

    Bookmark   May 29, 2013 at 10:16AM
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palimpsest

I've read a few articles on the necessary amount of ventilation and they tend to be toward the lower ends of CFM, 200s to 400s.

GW is the first place where I was made aware that your range hood was supposed to be able to suck a tennis ball through a garden hose.

    Bookmark   May 29, 2013 at 10:25AM
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ck_squared

"GW is the first place where I was made aware that your range hood was supposed to be able to suck a tennis ball through a garden hose."

Same here. My GC, who has been in the business for years, assures me that the guidelines for our area are more than sufficient for the home cook. When we remodel, we'll be using a hood with 290 cfm on our 36" gas rangetop. I am not worried and trust his expertise.

    Bookmark   May 29, 2013 at 10:42AM
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marti8a

I'm really glad I heard all the recommendations here before I bought one. I have a 600 cfm and even though I never intend to burn anything, if I walk away from the stove, it nearly always happens, and nothing smells worse than burned chicken and rice, my latest casualty. That hood cleared the smoke fast.

Without it, we probably would have had to sleep in the garage that night, or gone to a hotel.

This post was edited by marti8a on Wed, May 29, 13 at 10:50

    Bookmark   May 29, 2013 at 10:49AM
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scrappy25

Pal- love that imagery of a tennis ball being sucked through a garden hose!

Wow- really interesting to read the responses to this thread immediately after reading the concurrent "Do you think you installed the right range hood" (linked below). Of course most of those owners have the commercial strength ranges so does not apply to the ventilation we are talking about here.

Here is a link that might be useful: Do you think you installed the right range hood? thread

    Bookmark   May 29, 2013 at 12:15PM
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PRO
Sophie Wheeler

What the article recommends is a plain jane low powered consumer grade 30" range with that low powered vent hood. And it's not because that's the best choice for cooking anything. It's because it's the best choice for avoiding MUA.

He goes on to admit that those who install larger ranges with more firepower need the install the larger CFM's in their hood and MUA. They need to consider it a necessary expense as a whole package, and not a bothersome extra forced on them by a bureaucracy.

Since that's 95% of the people reading this discussion, I think the whole article in inapplicable to that 95% considering a pro style range. You still need the pro style hood and MUA if that's what you want to install in your kitchen.

Or, do what the article says and forget all that firepower and go back the 12K BTU burners on a standard Maytag.

    Bookmark   May 29, 2013 at 12:34PM
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palimpsest

Of course the article is subject to interpretation by the different camps of people depending upon what kind of range they want. But the vast majority of builders and buyers put in what is essentially the standard Maytag. It may be trying to Look like something else, but it's just a plain old range.

From a Green building standpoint, at least as they present it, there are reasons to avoid both a high powered cooking appliance and the need for make up air in a tight house.

    Bookmark   May 29, 2013 at 12:52PM
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cooksnsews

I think that article also ignores current thinking on the absolute need for proper air exchange in tightly sealed modern homes. Without such ventilation, moisture, molds, and other toxins can build up to unhealthy levels. Lots of tight, so-called energy efficient buildings (mostly commercial/office types) built in my market over the past 30 years have now been diagnosed with "sick building syndrome" and the health of many occupants has been compromised over that time.

In homes, it has been clearly determined that cooking is the most important contributor to indoor particulate pollution, and a significant amount of moisture. I my city, external kitchen ventilation is now mandated for all new builds, and significant renos.

    Bookmark   May 29, 2013 at 1:26PM
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rmtdoug

Nobody is saying you don't need any MUA in modern construction but if particulates are so fine as to permeate the entire house, they are certainly fine enough to be sucked upwards 3 feet into a vent by a 250-ish cfm fan. Sick building syndrome is primarily due to chemical outgassing of materials used in the construction, not due to particulates and water vapor from cooking or other human activities. I'm calling FUD here.

    Bookmark   May 29, 2013 at 1:52PM
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palimpsest

In general it would make sense to follow the manufacturer's guidelines for their range hood selection.

I agree that air exchange is important in modern, tight builds, but as I understand it MUA is in addition to Heat/AC air exchange, often directly linked into the range hood ventilation itself (?). I think green builders try to avoid this extra breech of the envelop, and mostly recommend induction rather than burning fossil fuels for cooking.

    Bookmark   May 29, 2013 at 2:45PM
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rosie

Regarding clearing smoke from burning, a nontechnical input.

We bought a very low-end insert special order from Lowe's. Don't know the CFM, but there was none lower available as this was the least expensive unit we could find.

Soon after moving in, I was called outside for a minor emergency that made me forget all about what was on the stove. Hiking back afterward, though, I remembered fast when I smelled the black smoke of badly burned food. We're not talking scorch here. Scared for our house itself, I ran up the hill, the smoke with me all the way, burst through the kitchen door--and left the smoke completely behind. Outside. Although any flames had burnt themselves out, the pan was still charring away on the stove, but our little-engine-that-could vent was quite adequate to its task. There wasn't even anything to clean up on the backsplash behind the stove. I actually hated to move the pot away from it long enough to rush it outside.

I don't regret that very satisfying demonstration of our vent's capability, even if I did have to throw a badly warped skillet away.

The end. :)

    Bookmark   May 29, 2013 at 5:53PM
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