Need Advice - Kitchen Hood/Makeup Air
malcience
14 years ago
Featured Answer
Sort by:Oldest
Comments (42)
malcience
14 years agolast modified: 9 years agoRelated Discussions
kitchen vent make-up air advice needed please (cross post)
Comments (73)So you have the Broan 6" MD6T and you have it unfiltered, unconditioned, and ouputting under the fridge for conditioning purposes? So you are relying on the exhaust heat of the fridge to cool the incoming air? How cold did it get this past winter for you? How cold was that make up air? Detectable at all? Here we had -20 real feel in NY with the wind chill at times. It was brutally cold and cold often. I think I might have to put in a heated MUA. So update on Broan. The lady I spoke to today was completely useless. To make a long story short she had absolutely no idea how to use the Make Up Air Specifier on her site. It was quite pathetic and my impressions of Broan's customer service = suck. I spoke to Dean at Electro Industries at length about all the factors I'm thinking about. We went over two options - one using the MA-10 (10kw all in one 10" heater with damper, blower, filter, and current detector to control blower speed) and the less expensive heater unit EM-WX1025R. The broan MD6T comes with a 24volt 20VA transformer so I could then use the one signal to turn on both the Broan damper and the heater unit. Both options unit can accomodate up to 637cfm in a 50 degree temperature rise. It's a 10kW unit though and would require a 50A or 60A two pole (240V) breaker and its own dedicated lines (of course). I can take care of the electrical so no problem there but man I'm guessing my heating bill (which was astronimical last year) will be more than I can tolerate this year. Temperature Rise Needed/CFM EM-WX1025R 10000 Watts 80/395 70/452 60/527 50/632 40/790 30/1054 MA-10 $1917 + freight EM-WX1025R $800 + freight. I think that should be sufficient - it's better to have 50 degree air coming in than 0 degree air. I'm thinking that maybe I can get away with non-heated air if I can get fresh air to come up that old supply register near the range. The opening is closer than the fireplace but it might work if I put a blower in-line as well....See MoreNeed advice for a make-up air system for vent hood
Comments (10)First, this is what the proper calculations would say about Risinger's installation. OR THIS Second, short circuiting a hood, air curtains, and generally any makeup air introduced too close to the range will produce counterproductive turbulence that will reduce the effectiveness of the hood to the point that he may as well have just put in a 400 CFM fan without makeup air. Third, the floor under the range is required to be sealed from drafts on most ranges. But, you can't usually shove ALL that air through the HVAC system either...See Morerange hood make-up air: thoughts on interesting white paper?
Comments (6)Since the structure isn't going to deflate and collapse when an exhaust system is running, the amount of air that goes out an exhaust system is limited to how much outside air comes in the structure at other places. A make up air system is a great approach. All houses need regular fresh air anyway, both purposes can be served. Older houses are usually not tight - think not only around windows and doors, but through the walls (electrical sockets and switches, pipe runs through walls and similar unsealed breaks in the wall, through the floor up from a crawl space or basement, unsealed areas around HVAC return or supply grill boots, etc.). Unless all of these have been sealed. It's not often done other than in extreme weather areas. In times of mild weather or otherwise, cracking a window to allow in fresh air helps an exhaust fan (whether for cooking or even in a bathroom) work better. Gas appliances if inside the structure should be in areas that are closed off from inside air so that backdrafting can't happen. In my house, I have two "closets" (one for a water heater, one for a furnace) that are within the exterior walls but both closets have outside air supplies and exhausts and the doorway edges are sealed tightly with raised threshholds and tight weatherstripping around the door frames. When gas appliances are in a basement, the best approach is to similarly close them in an airtight room or otherwise closed off with outside air supply for combustion....See Morerange hood and ventilation questions- makeup air, ducting
Comments (7)Well, I can be long and rambly too, and suggest reviewing the many hood threads here to see that demonstrated. I can also suggest that if you, @Margaret Davis, do so, you will learn a lot more about both hood requirements and make-up air (MUA) requirements. I'll supplement the information on this site, first by noting my astonishment that whoever wrote that blurb for Proline seems to be missing the most fundamental concept -- no air leaves the kitchen that doesn't get replaced. No reports of imploded houses due to hood blowers pulling a vacuum have ever come to my notice. With respect to the requirement that outgoing air be matched by incoming air, the size of the kitchen is irrelevant. The blower size is irrelevant. How long you run your hood is irrelevant. There is always a balance such that the actual hood duct airflow matches what leaks into the house, or is allowed to flow into the house, or is deliberately blown into the house. Gag the MUA, and the house interior pressure drops until the hood blower volumetric flow rate matches what can leak in at that pressure drop. The controlling aspect is the 'fan curve' of the hood blower when MUA is passive (not blown) and the combination of fan curves when the MUA is active (blown). Example fan curve [click to enlarge] Broan 1200 CFM blower fan curve. The pressure that determines where one can operate on the fan curve is determined by pressure loss passing the hood baffles, the ducting, the exterior cap if not included in the fan curve, and the MUA pressure loss getting air back into the kitchen. With a large diameter passive MUA or imperfectly tuned active MUA, you are likely to see the actual hood air flow to be only 2/3 of the zero static pressure flow rate, that is, 2/3 of 1200 or 800 CFM. Modern codes require, as @Celedon noted, deliberate (active or passive) MUA when the hood rated blower size (not actual flow rate) exceeds 400 CFM. This is to ensure that any combustion appliances that are present, or may be present in the future, are not back-drafted by negative house pressure thereby introducing carbon monoxide into the house. Second, I won't go into hood requirements here as those should be easily found among the hood threads, and in any case you seem to have picked a hood or hood size. However, I will address the vertical duct question. Generally, the highest pressure losses will be the hood baffles and the MUA if passive, depending on duct size and filtering. So longer ducts will drop the overall flow, but perhaps not too much relative to these causes. This can be evaluated by plugging the duct parameters into on-line calculators that may be found by searching. Third, most ventilation noise is air turbulence noise, dominated by that at the blade tips of the blower. Duct turbulence will also contribute. Silencers reduce this, and may (as in the case for me) reduce the noise such that baffle turbulence (hiss) dominates. An advantage of running the duct into the attic would be that in the attic there may be room for a silencer to be inserted between the external blower and the hood. One can also angle the ducting there so that the external blower is at an advantageous point on the roof. No matter what tortuous path you choose, and the ducts you have sketched aren't really that long, be sure that the chase allows access to the ducting in case cleaning is needed (usually rare in residential cooking). In cold climates it is best to keep the duct warm over as much length as possible, so exterior ducting may want to be in a chase if very long. With a larger chase, a silencer can be put closer to the hood, which helps suppress duct noise. Fire protection in the chase may be an issue; discuss with your code enforcement officer. You should plan on using at least 10-inch ducting, but note that the Fantech 10-inch duct silencer is 14 inches in diameter by 3 ft long....See Moresfjeff
14 years agolast modified: 9 years agoweissman
14 years agolast modified: 9 years agoJohn Liu
14 years agolast modified: 9 years agoUser
14 years agolast modified: 9 years agocooksnsews
14 years agolast modified: 9 years agomoose_2008
14 years agolast modified: 9 years agoweedmeister
14 years agolast modified: 9 years agomalcience
14 years agolast modified: 9 years agoblindstar
14 years agolast modified: 9 years agotoddimt
14 years agolast modified: 9 years agokaseki
14 years agolast modified: 9 years agomalcience
14 years agolast modified: 9 years ago3katz4me
14 years agolast modified: 9 years agoscrappy25
14 years agolast modified: 9 years agosfjeff
14 years agolast modified: 9 years agoigloochic
14 years agolast modified: 9 years agocooksnsews
14 years agolast modified: 9 years agomalcience
13 years agolast modified: 9 years agokaseki
13 years agolast modified: 9 years agomalcience
13 years agolast modified: 9 years agocanyonhome
13 years agolast modified: 9 years agomalcience
13 years agolast modified: 9 years agokaseki
13 years agolast modified: 9 years agomark_g
12 years agolast modified: 9 years agoajthompson
10 years agolast modified: 9 years agokaseki
10 years agolast modified: 9 years agotransy416
10 years agolast modified: 9 years agokaseki
10 years agolast modified: 9 years agotransy416
10 years agolast modified: 9 years agokaseki
10 years agolast modified: 9 years agotransy416
10 years agolast modified: 9 years agokaseki
10 years agolast modified: 9 years agotransy416
10 years agolast modified: 9 years agokaseki
10 years agolast modified: 9 years agotransy416
10 years agolast modified: 9 years agokaseki
10 years agolast modified: 9 years agotransy416
10 years agolast modified: 9 years agokaseki
10 years agolast modified: 9 years agoroslynchauvin
5 years agokaseki
5 years ago
Related Stories
KITCHEN DESIGNSmart Investments in Kitchen Cabinetry — a Realtor's Advice
Get expert info on what cabinet features are worth the money, for both you and potential buyers of your home
Full StoryKITCHEN DESIGNHow to Choose the Right Hood Fan for Your Kitchen
Keep your kitchen clean and your home's air fresh by understanding all the options for ventilating via a hood fan
Full StoryKITCHEN APPLIANCESWhat to Consider When Adding a Range Hood
Get to know the types, styles and why you may want to skip a hood altogether
Full StoryMOST POPULARMy Houzz: Open-Air Living in the Mountains of Bali
Community, jaw-dropping beauty and sustainability come together in a tropical paradise for a London expat
Full StoryKITCHEN APPLIANCESThe Many Ways to Get Creative With Kitchen Hoods
Distinctive hood designs — in reclaimed barn wood, zinc, copper and more — are transforming the look of kitchens
Full StoryKITCHEN DESIGNA Cook’s 6 Tips for Buying Kitchen Appliances
An avid home chef answers tricky questions about choosing the right oven, stovetop, vent hood and more
Full Story5 Stunning Modern Range Hoods
Today's kitchen range hoods can look like sleek sculptures. Here's what to look for when you go shopping for one
Full StoryKITCHEN DESIGNWood Range Hoods Naturally Fit Kitchen Style
Bring warmth and beauty into the heart of your home with a range hood crafted from nature's bounty
Full StoryKITCHEN DESIGNModern Storage and Sunshine Scare Away the Monster in a Kansas Kitchen
New windows and all-white cabinetry lighten a kitchen that was once dominated by an oversize range hood and inefficient cabinets
Full StoryHOUSEKEEPINGHow to Clean Your Range and Oven
Experts serve up advice on caring for these kitchen appliances, which work extra hard during the holidays
Full StoryColumbus Area's Luxury Design Build Firm | 17x Best of Houzz Winner!
sfjeff