Makeup Air, will this work?

5 years ago

I'd love some expert opinions on whether a makeup air plenum mounted on the vent hood will work. I saw this https://youtu.be/u2uVaTMXd_8 on and it looks good in principle. If the link doesn't work, go to YouTube and search "performance smoke test ns builders"

It looks really good, the question is whether having the return air so close to the vent will diminish the volume of air/effluent the vent will be able to exhaust. But....it's very similar to commercial restaurant setups with the return plenum right there near the exhaust, so who knows. CaptiveAire has a 48" vent with available makeup plenum, so I don't know why this wouldn't work, so long as you get the numbers right.

My range is a 36" with 6 burners, max output of burners is 90K BTU, I'll never have them all on at once, but I will be blackening/searing, making some pretty serious curry, rouxs, and 5-hour seafood stocks. I'm going to install a 42" hood with at least an 800 cfm inline, the duct will run straight up through the roof. Maybe have 2 ninety degree turns, but only if I must!

I'm trying to avoid bringing untreated air into the house anywhere not right at the stove, but don't want and ugly vent in my new kitchen!

Thanks in advance, everyone on here has been quite helpful.

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Comments (2)

kaseki
5 years ago
Things the commercial hood studies (such as by the California Air Resources Board) have found are: (a) Don't short circuit the rising cooking plume effluent with the MUA, and (b) Avoid turbulence in the MUA supply to the cooking zone so that it not disrupt the plumes, thereby causing escape into the kitchen air.

I suggest reviewing the first 22 pages, more or less, of the Greenheck Guide, available here:

https://www.tagengineering.ca/wp-content/uploads/2015/02/KVSApplDesign_catalog.pdf

Commercial cooking devices are typically raised from the floor, allowing MUA to be brought down behind the panel connecting the cooking device to the hood rear plenum edge, and dumped on the floor under the device where it diffuses out into the kitchen air. For residential cases, I recommend dumping the MUA at a ceiling or soffit using a diffuser (not a register) to aim the MUA in a desired direction. If the diffuser is close to the hood, then the direction is away from the hood. If the diffuser is across the room or down the hall, then aim it toward the hood, perhaps with some depression to increase room mixing. Any MUA not short circuiting the rising plumes will have to be heated in very cold external conditions. All this is really too brief to do the subject justice. See the Greenheck Guide for a more exhaustive description.

I have seen CaptiveAire systems with MUA apparently being dumped on the cook's side of the commercial hood. This is done from a height of maybe 10 ft off of the floor, using a hood with the standard bottom of 7 ft from the floor, and a hood entry aperture that is quite large relative to the cooking appliance. I think that can work in dropping air far enough from the plumes to allow it to mix into the air flow low enough to enhance plume capture. I haven't studied this, however.

For the hood, use an airflow of 90 CFM per square foot across the hood entry area. Choose a blower rated CFM such that with the pressure loss of the baffles, ducting, and MUA system it will flow at this rate.
Chris thanked kaseki
Chris
Original Author
5 years ago
Thanks, some of it is Greek to me, some I understand, now I have some homework to do!
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