Make up air vent location for range hood? (2023)

  • Milly Rey

    5 years ago

    Your location would essentially short circuit the air flow. The hood would be pointless.

  • weedmeister

    5 years ago

    Yes, you're overthinking about rats.

    Ceiling is another location, middle of the room. Also under the floor cabinets with screened openings in the toe kicks.

  • Related Discussions

    Vent-A-Hood vs Kobe range hoodQComments (25)I have installed 3 different brands of range hoods in the last few months: Kobe, Zephyr and Faber. Each one advertised low sones at the slowest fan speed. Each one of them did not measure up and not by a little, but by over 15 dB. I use both a dedicated Radio Shack db meter and an iPhone app (which are in agreement with each other). None of the three measure below 60 dB on their low (quiet setting). By the way, the ambient in my kitchen, with the refrigerator running is about 44 dB. Kobe just said to return theirs, they could offer no comment of the failure of their unit to meet it's specs. Zephyr gave me the installation/duct work run around. After I was able to demonstrate by measurement both installed, without ducts and uninstalled sitting on a counter, that less than 3 dB difference is found in those things, they had no answers either. (I got stuck with a 20% restocking fee because I used a local dealer) . Faber I didn't even try support. Neither Kobe nor Zephyr could describe the conditions under which their measurements were made, so of course, my measurements could not be comparable. All I can say to this is, that for most people, the sound the hood makes, when standing in front of it cooking ( I used ear level at 12" from front of hood) is what is important. And no one making these hoods will claim such a measurement. There must be some reasonably quiet hoods on the market, but I have no idea how any consumer could find one. Local dealers are not much help either. I live in the Metro-Atlanta area and have been to 4 showrooms and have been able to listen to and measure exactly 2 hoods! Most showrooms do not bother to hook them up. The sales people have no idea on noise levels either, most of them have never heard the hoods they are selling....See MoreWhy is cold air venting through my range hoodQComments (4)Do you have a wood burning fireplace in the house? ( a great place for warm air to get sucked out of the house creating negative pressure in the house which is then made up by pulling cold air in from your vent hood). If you have an upstairs with a poorly sealed attic hatch, or bathroom fans that don't close and seal properly? There are many places a house can leak warm air if it has not been carefully dealt with. Are there any obvious places in your home?...See MoreVent Hood and make up airQComments (1)I would say no. But "it depends" is another answer. Depending upon the distance to the vent from the cook top. Personally I would want 600+ CFM. I am in a similar situation and I am getting an 1100CFM. Because the vent will be 45 inches off the cook top....See MoreMake-up air vent located at ground levelQComments (2)@Patricia Colwell Consulting The damper needs to connect to the return on the furnace, which is in the basement. The ceiling in the basement is right about ground level so that's the limitations we are working with. There is an old grate in the basement wall to the outside that happens to be in the perfect location for us to repurpose so we were going to knock that out and install the damper/ducting there... there's kind of a window well there built around it that protects it from flooding since it is right at/slightly below ground level. But that all said, we need something else built around this or connected to it to keep it from getting blocked. So perhaps an enclosure with a little roof and a grate to allow air flow? Or perhaps connect ducting to the outside of the damper and put a cap on top like on roof vents?...See More
  • catinthehat

    Original Author

    5 years ago

    Make up air vent location for range hood? (4)

    Haha yes good point on the rat issue. I've been researching the last few days to see if anyone at all has done any CDF analysis on a range/hood/make up air setup, and while I surprisingly did find something somewhat related, I'm still debating what it means for my application.

    Here's an image excerpted from the research paper showing a thermal gradient of a range being exhausted, with a makeup air vent blowing into the room directly in front of the hood at 150 fpm (not passive). You can see how the makeup air brings hotter air from the outside, circulates this air immediately in front of the range, and is eventually exhausted. This would be an ideal setup since the makeup air is serving its purpose and not heating up the rest of the house. Win win.

    Unfortunately I'm not so sure what the outcome would be in a passive system I would be installing. I have access to CFD software at my work, but I'm not sure I have the time...I may have to revisit the floor idea and think more about the rats...I like that floor cabinet idea as well.

    Full paper for those interested:

  • Milly Rey

    That is a commercial range hood that comes out a LOT farther from the wall. It doesn’t really apply at all.

    Dont know if you’ll get the square footage needed for a passive system in the toe kick...

  • cpartist

    5 years ago

    Kaseki isn't on the appliance forum. You should ask there

  • catinthehat

    Original Author

    5 years ago

    Hey there Milly, interestingly enough, it does appear as if the direction and flow of the active makeup air system is actually pushing all heat to the back of the hood. To my eyes in this example at least, the extra depth of the hood doesn't do much (or maybe it actually helps direct that flow back??) Only a CFD model with a more typical residential setup could answer that though. Either way, the setup clearly doesn't represent mine, but I do think there are some parallels to be drawn.

    I think I will end up placing my MUA below the range given the results of the linked model. The curtain of air being pushed down and then sucked back up seems like it could be nicely approximated by a passive system directly below the range. I'm actually surprised this setup isn't recommended more often. I've seen one YouTube video of a contractor showing this install method, but no literature.

    There is enough surface area under the bottom of a 48" range to accommodate the flow of two 10" vents so I may just do that. Two dampers from Broan are not cheap though =(. Funny how the hidden costs of a remodel add up.

  • Fred S

    5 years ago

    You had better go back to step 1 and check your range installation instructions. They generally say to seal all holes in the floor and back wall because they are not designed to have air brought in underneath them.

    catinthehat thanked Fred S

  • catinthehat

    Original Author

    5 years ago

    Hi Fred,

    Great point, thanks. I had brought up that question with Bluestar recently, and their response to me was the hole sealing was to prevent heat from entering areas of the home that may not tolerate high temperatures. I had originally asked because I also have a hole behind the range I built into the wall with a lid which would allow me to service/clean the entire bottom of the range from the rear.

  • opaone

    5 years ago

    When we were having a Wolf installed during a kitchen remodel the gas (HVAC) guy said that instead of running a new larger line ($$$) that he could move the existing line over to the HP side of the regulator and put a regulator on the range. Only problem was that the regulator stuck out the back and prevented the range from being pushed all the way back.

    No problem thought the HVAC guy, nothing a hammer and a punch in the sheetrock can't handle.

    "Uh, dude, you just punched a big hole in to a return plenum that you think is going to have a natural gas regulator stuck in it and in any case will suck whatever is in that area behind the range and around that regulator in to our HVAC system."


  • Fred S

    5 years ago

    last modified: 5 years ago

    "I had brought up that question with Bluestar recently, and their response to me was the hole sealing was to prevent heat from entering areas of the home that may not tolerate high temperatures." - That is NOT the reason, which just goes to show you that they will tell you anything you want to hear. ALL clearances are to COMBUSTIBLE materials to begin with.

    There is not a single employee at Bluestar that has the authority to contradict or override the "Listing and Labeling" of the third party , independent, testing laboratories. (NRTL) - THAT IS the reason that the testing and approval is done by an independent laboratory.

  • catinthehat

    Original Author

    5 years ago

    Hi Fred thanks, what is your thinking then as to the reason to seal up holes in the rear and bottom? I am genuinely curious.

  • Fred S

    5 years ago

    In order to begin to understand it, you would need to buy ANSI Z21.1 for about $650. There is some very technical engineering, even though it doesn't look like it, in the ventilation between walls of the oven and cooktop sides that ensures that the cabinets up against the range will not get hotter than 194°F. If you block the airflow by lowering the range (some people try modifying the feet for thin countertops that make them less than 36" tall), or putting ducts in for MUA, the outside wall of the range will get hotter. If you force that much extra air through the range, (push or pull) you change the way the gas burns, and create CO problems. Even if you can adjust the air shutters to compensate, you would then have to turn on the entire system just to make a pot of tea, in order to get enough air to get a clean burn. With holes in the floor or back wall, the natural draft intended/engineered to cool the outer walls of the range can be disrupted or diverted, leaving the heat to build up around the range - nothing to do with heat in other areas of the home. What can't tolerate more heat than the wood cabinets around the range? Another separate reason for no holes is the possibility of a gas leak. How much gas do you think that duct will hold, just waiting for someone to create a spark?

    The testing standards do not say no holes "unless someone thinks of some unusual excuse".

    catinthehat thanked Fred S

  • catinthehat

    Original Author

    5 years ago

    Thanks Fred very informative. I find it interesting how the instructions state to seal up holes in the rear wall and floor, but nothing about the sides. I think there is wiggle room in the design but without talking to the designers directly couldn't confirm. I may vent from the floor on the sides of the range up through the cabinets to be safe though. Thank you very much!

  • Fred S

    5 years ago

    last modified: 5 years ago

    "I find it interesting how the instructions state to seal up holes in the rear wall and floor, but nothing about the sides." That is because the traditional design of a freestanding range has been developed such that the sides are designed to be either exposed or adjacent to a base cabinet.

    "I think there is wiggle room" Not enough for MUA. I figured roughly a velocity of 1800 f/m around the base of the range without taking off the front lower panel. That is 3X what a normal HVAC duct would be. That is for a 1200 cfm hood, and if that location of mua was actually of significant proportion.


  • bostonbob3

    last month

    I found this very interesting (and very odd): //Interestingly, exhaust from toilet rooms, bathrooms, and kitchens is not considered hazardous or noxious, and the IRC explicitly allows makeup-air intakes to be located near these vents (in other words, your kitchen makeup-air intake can be right next to your kitchen exhaust-vent termination).//

    The Basics of Makeup Air - Fine Homebuilding


How far does make up air have to be from exhaust? ›

800 CFM would require a minimum vent size of 7” but most professionals would use an 8” or 10” vent to increase the efficiency of the hood vent. So, if you use an 8” duct above your range, then you need to bring in a minimum of 8” of “make-up air”.

Where do you put makeup air? ›

per minute (cfm) be provided makeup air at a rate approximately equal to exhaust. This air has to either be discharged into the same room as the range hood, “or into rooms or duct systems that communicate through one or more permanent openings with the room” where the range hood is installed.

Do I really need make up air for my range hood? ›

Even with a powerful hood, you may not require makeup air if it is installed in a large kitchen or well-ventilated space. However, if you live in a small space or the ventilation is not adequate, make up air is likely a good option for you.

How do you put air in a range hood for makeup? ›

In this article, energy nerd Martin Holladay outlines various solutions that allow range hoods to function well in tightly built houses. You can bring makeup air into a tight house in three ways: through the HVAC system using dampers; through wall- or ceiling-mounted grilles; or through mechanized makeup-air solutions.

Do I need make up air for a 400 CFM? ›

In the US, the construction industry has long recognized the need for adequate makeup air for exhaust systems. Beginning in 2009 and in every version since, the International Residential Code (IRC) has required that makeup air be provided for kitchen hood exhaust systems with capacity of 400 cfm or greater.

What happens if you don't have make up air? ›

What happens if you don't have enough make up air supply? Without enough make up air, the building pressure becomes negative. This can cause all kinds of problems and wreak havoc on your entire ventilation system as well as the comfort of your personnel and customers.

Where do you put a backdraft damper on a range hood? ›

A backdraft damper can be installed inline with your ductwork or at the connection between your hood and the ductwork. For the best results, install an inline backdraft damper a few feet away from the outside of your home. Backdraft dampers are vents that go inside your duct.

What temperature should kitchen hood makeup air be? ›

To maintain occupant comfort, most design guidance recommends providing a makeup air supply temperature within 10 degrees F of the room temperature. For example, if a house is maintained at 70 degrees F in the wintertime, the makeup air should be provided at a supply temperature of no less than 60 degrees F.

Is it necessary to use make-up air? ›

A make-up air solution is recommended for buildings where environmental conditions warrant a greater need for ventilation not only to improve the quality of air within the building, but also protect the health of those inside.

Is makeup air the same as outside air? ›

Makeup air is outside air that replaces air exhausted from inside the building. In most houses, there are several appliances that push or pull air out of the house, including clothes dryers, bathroom fans, fireplaces and kitchen range hoods.

What is the purpose of make up air? ›

Make-Up Air is Replacement Air

Make-Up Air units are designed to replace exhaust air by bringing in fresh outdoor air into the space and heating or cooling it to the desired condition and discharge the conditioned or tempered air into the building.

Where do you put a make up air damper? ›

Note: The fresh air damper is installed into a completely separate duct independent of the range hood ducting. The ductwork and make- up air damper are linked into your return air side of the central HVAC system OR a separate duct coming from the outside directly into the kitchen.

Where should a hood vent be placed? ›

Determining the best range hood height involves factors such as the type of range hood, the type of cooktop and your kitchen's layout. If you have an electric cooktop, range hoods should typically be 20–24 inches above the heat source. For gas cooktops, your range hood should be around 24–30 inches above the stove.

Should a range hood be flush to the front of the stove? ›

Yes, for the best coverage and most efficient ventilation, your range hood should be flush to the front of your stove. It should extend at least to the middle of your front burners.

How does make up air work in a kitchen? ›

Simply stated, a make up air unit pulls air in to your space from outdoors and conditions it to the indoor temperature, to replace air that's pulled out by your kitchen exhaust equipment. Without it, you get back drafting, poor temperature control, negative air pressure and air quality problems.

Is 400 CFM enough for range hood? ›

To power your range hood, you need at least 100 CFM for every 10,000 BTUs of your stovetop. For example, a 100,000 BTU stove needs at least a 1000 CFM range hood. For electric stoves, multiply the stove width by 10. So, for a 42” electric stove you want a range hood with at least 420 CFM.

What happens if CFM is too high? ›

Not only will this exhaust fan be drawing more energy than necessary, but the extra CFM might cause other issues like drafts or the inability to dry up the moisture still hanging around in the bathroom.

How many CFM do I need for a 12x12 room? ›

One cfm is needed per square foot (1 cfm/sq ft) of floor area. This is the average air quantity required for a room or an entire building.

What happens to your body when you stop wearing makeup? ›

A brighter, healthier complexion, as well as fewer clogged pores and potentially even less blackheads, pimples, and breakouts. The longer your skin goes without makeup, the better it will be able to stabilize sebum or oil production, hydration levels, and its natural mechanism for exfoliating dead skin cells.

How do you make air not stuffy? ›

4 Tips for Improving a Consistently Stuffy Room in Your Cheverly, MD Home
  1. Open the Windows. One way to immediately freshen up a stuffy room is by opening the windows on a cool day. ...
  2. Turn on the Fan. Running a fan in a stuffy room helps circulate the air, making it feel fresher. ...
  3. Address Musty Items. ...
  4. Use a Dehumidifier.
Apr 28, 2017

How do you do no make up make up look? ›

8 Tips To Create The Perfect No-Makeup Makeup Look
  1. Prep your skin. To nail a no-makeup makeup look, you need to have a strong skincare routine. ...
  2. Ditch the foundation. ...
  3. Conceal correctly. ...
  4. Add some colour to your cheeks. ...
  5. Illuminate your face. ...
  6. Go easy on the eyes. ...
  7. Aim for the My Lips But Better look. ...
  8. Mist away.

How much clearance do you need above a vent? ›

Vents Need 10 Inches of Space

These vents need at least 10 inches of clearance to work, but more clearance is better. Move any rugs that are covering return vents in the floor. Shorten curtains that hang down and cover your vents.

How much clearance does a furnace exhaust need? ›

Single wall flue vents require a six-inch minimum of clearance to combustibles, and B-vent (double wall) requires minimum 1-inch clearance.

Where should an indirect fired makeup air unit be installed? ›

Mounted indoors or outside on a slab or roof mounted on a curb the Price AW-I units are an excellent option for providing conditioned air to hospitals, hotels, condominiums, shopping malls, and factories. AW-I units can incorporate DX cooling, energy recovery, and customized controls to meet application specific needs.


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