Hi Lumine,

I am in the same position as you, choosing a oven hood/extractor fan. I think I've settled for the Vent-A-Hood Magic Lung because I plan to have the hood cover built on site and due to the size of my range. I also need a 1200 CFM fan for a 60" range hood. I considered Modern-arie and BEST by Broan, but the Vent-A-Hood seems to fit my needs better.

One thing I've learned in the research process is that the code in many areas also requires a makeup air unit for fans over 900CFMs. The size of the fan is dependent on the BTU's your range will put out.

I wanted to point this out because it seems that many of the range and vent hood companies don't volunteer the information to their customers. I only stumbled upon it, but it can add significantly to the overall cost depending on the codes for your area. In addition to the MUA unit, the code in my area requires that I also install a air tempering unit.

Because I discovered the requirements for MUA and the tempering unit early enough in the process, I was able to research and present my builder and his HVAC guy with a solution that was much less costly than the unit he normally uses for MUP, which was quoted in the neighborhood of $10,000.00, this was in addition to the price of the hood and the range! If I hadn't found alternative unit, the range of my dreams would have been out of the question for me.

Good luck!

>I was able to research and present my builder and his HVAC guy with a solution that was much less costly than the unit he normally uses for MUP, which was quoted in the neighborhood of $10,000.00, this was in addition to the price of the hood and the range! If I hadn't found alternative unit, the range of my dreams would have been out of the question for me.

Could you go into more detail about the differences between the solution the HVAC guy proposed and the less costly solution? I think a lot of people on this forum will find it helpful.

You didn't say how far it is between hood top and ceiling. My impression is no attic exists between ceiling and roof. An external fan will likely be slightly quieter than an internal fan, but it would be helpful to have room along the duct for a silencer. These are about 2 ft long for 8-inch ducts and 3 ft long for 10-inch ducts and could be enclosed in either a cabinet or stainless steel shell above the hood if there were room.

I've never seen this, but a taller stack (or chase) on the roof could enclose a silencer with the blower assembly on top.

Another way to go quiet would be an industrial/commercial upblast blower assembly on the roof operated at the lowest fan belt sheaf ratio available so that a larger fan was running at a low speed when at maximum motor speed. (Similar in a way to how much air a Casablanca type ceiling fan can move quietly at low speed.) With an intended 600 or so actual CFM, the ducting could be smaller than the upblast unit might normally interface with. Your HVAC person should be able to discuss this with you if he deals in commercial work.

There is always MUA. If it is too restrictive you won't get much hood flow rate, the house pressure will go negative, and combustion appliances may backdraft toxic carbon monoxide. At a minimum, MUA comes from house leakage. The hood flow rate at which added MUA is required varies with locality and in the more enlightened areas, with risk due to backdrafting.

For example, there is little risk of backdraft CO when there are no combustion appliances. Or when such appliances are in their own room with its own MUA.

Otherwise, whole house MUA means that issues of air conditioning (or at least warming), filtering (causes pressure loss requiring fan enhancement), ducting, and control become significant and costly, although $10k strikes me as way overboard for most residential applications unless cooling is also required.

kas

Sure, I found a system from CCB Innovations that can work with any exhaust hood. Modernaire also sells a unit, I think they are both made by CCBI since the product numbers are the same. There are three units 6", 8" and 10" and are all priced at just under $300.00.

From what I understand both units can either be installed near the range hood site or attached to the HVAC system. There are videos to explain how this works on their sites.

I personally thought attaching it to the HVAC system was the best option since it would cause the heater to kick on and automatically temper the cold air as it entered the house. My county code inspector would not approve it being installed into the HVAC though. So, it will have to be installed in my kitchen along with the additional tempered air heater that I've been told will run about an additional $3,000.00 -$3,500.00. Still way better than the $10,000 my builder first mentioned to me. I'm sorry, I don't have any details as to what unit my builder normally uses when he installs MUA.

Thank you for the quick replies! Well ... this just got more complicated!

I should mention that the house is in San Francisco, CA, so the climate is fairly mild and I don't expect air tempering to be needed. From what I've been reading though, MUA is probably something I will need to factor in. It's a small house so I'd think about incorporating the MUA into the heating ducts to keep it tidy (there is no A/C in the house because it isn't needed in SF).

There is no attic in the house, the ceiling in the kitchen is 8' so the hood will probably be a little less than 30" below the ceiling; then there will be a short duct to get through the 8" or so roof; and then you have the atmosphere. So, if I needed extra duct length for a silencer, I could put up an angle and run the duct horizontally along the roof (I'd obviously rather not do this unless we are certain that it will make a big difference in noise).

Just to give you an idea and personalize this a bit, a 3D plan of the house is below.

Thanks again and I look forward to more comments on selecting a hood and blower.

Hi, Just jumped in on this topic. For your application 36" gas range i would recommend ventahood brand dual blowers (600 posted cfm with eq of 900) But with that said hoods are like jewelry there are lots of styles and flavors. Bestbybroan as you mentioned is very nice as well. Style of hood is one thing and CFM is another as like other have mentioned make up air can come into play and should be considered.

Goodluck i wish you the best in your hunt!

I was leaning more towards something in the 1200 cfm range. Does that seem excessive for my application?

Also, I'm curious, instead of putting in a complicated MUA unit, why can't one just put in a flap valve (like used for dryer vents but reversed) so that the house can just suck in air whenever there is a vacuum? This way, both the bathroom fan, the hood, and whatever else pushes air out can benefit. I can understand how in harsh climates maybe there is an insulation issue with that but in San Francisco I don't quite see the necessity to have a mechanically operated valve to break the vacuum. Thoughts?

@lumine
Yes, 600 cfm Ventahood is enough and its rated at 900 working cfms i have a 1200 cfm over a 48" Bluestar and we never ever activate the last blower as its not needed. Things like height above the range is important and depth and even width so that you have maximun coverage area. If you choose a non ventahood brand you will need to go higher on the cfm for use with grill.

make up air units need to be connected to the hood controls to allow air to replace the air that is drawn from the home hence you need proper equipment.

Ventahood vs other hoods go to the ventahood site and read and watch the videos then compare. Ventahood is a very popular hood for over pro style gas ranges for years..

I'm not saying its the one for you but worth a look.

I agree with Trevor. I have a 36" Blue Star with a grill and a 42" x 24" Modernaire with a 1200 CFM fan. It works great.

27" depth would be a bit better for capture from the front burners but I have a VERY skinny kitchen and a tall husband, so I really couldn't see going with a 27". Mostly everything gets captured.

I only have an 8" duct because of a riser that could not be moved so the fan is noisier than it would otherwise be but I would trade more noise for no grease any day.

MUA via a balanced flapper valve (damper) is certainly one useful method, so long as the house pressure does not fall more negative than about 0.03 inches of water column. You may have to consider how large a critter you want to block in its duct, and if the critter is smaller than a grasshopper, what the filter pressure drop will be at the flow rate that is achieved using either normal blowers or magic ones.

kas

From vent a hoods site

Magic Lung® blowers can be configured to provide the power you need for even the most demanding cooking surface. Each highly efficient Magic Lung® blower supplies 300 CFM of air movement; you can combine multiple blowers in a single Vent-A-Hood® to create the perfect ventilation for your cooking surface.

That clearly states a 300cfm blower MOVES 300cfm

I would have thought if the 600 = 900 statement is correct Vent a Hood would put it on the page explaining the benefit of the Magic Lung or maybe its not on the main features page but elsewhere that i did not see which could be the case.

Here is a link that might be useful: Vent a Hood Magic Lung

Thank you all for the replies! Looks like I am narrowing down which brands I should be serious about and I welcome more comments, particularly about quiet hoods.

Another question I have is, unfortunately there is a joist running right down the middle and behind where the hood will be. What are good options for routing around the joist so I don't have to cut it? Do any manufacturers offer off-center ducts?

I will start out by saying that I am not an expert in range hoods, but I have done a lot of remodeling and have often found that prices for common items can be outrageous. As a reality check for the OP take a look at the link below which shows the selection at Costco. The highest priced one is $1000, and all the rest are less than that. A similar search on Amazon or Build.com also shows a wide selection of range hoods that are realistically priced.

Here is a link that might be useful: Range Hoods

You would be better to offset as opposed to try to work around the beam.

All ModernAire hoods can be offset left or right, top or back

I appreciate the advice, and thanks for watching out for my wallet!

Looking through various hoods, I find that I'm attracted to flat types like the one below by BEST. However, I am a little concerned that this design would compromise performance for the flat look because I would assume that less suction happens towards the perimeter. Does anyone know if these types of hoods work almost as good as the more bulky varieties?

$10,000...sounds like the usual 200% profit to me...do you make that much profit on your jobs… I would competitively bid that contractor.

If one spends several days reading hood ventilation topics here, one will eventually learn all the opinions about every topic, including all the questions raised by this thread. But on the specific questions raised above, I have these points for the OP to consider:

o The most efficient hoods (in capture, containment, grease capture, and flow rate) are used by commercial kitchens, so residential designs embracing those features should be better than alternatives. Mere copying a look may be insufficient if the design is not tested. I expect Broan to perform some testing, but I don't expect them to make a hood of some configuration do more than it can.

o Alternatives to hoods incorporating commercial principles may be good enough depending on the user's needs (i.e., fanatical opinions about grease and odor). I think this Best hood would be fine for modest cooking chores, but inconsistent with bullet two of the OP's opening message.

o Mesh filters require being cleaned often or they will gag the flow

o Given enough pressure loss across the meshes in the image above, the flow will tend to even out over the aperture areas. If there were low pressure loss at the mesh filters the narrow height of this style would tend to favor flow in the center rather than the edges. This is why the lower pressure drop conventional baffle designs have so much height.

o This hood has no capture volume, so it is critical that rising effluent be immediately pulled into the mesh. This only happens where the mesh is, and the area of mesh presented to the effluent is not completely clear to me from the photo. The mesh is the boundary between the capture zone and the containment zone. More conventional hoods have a capture volume, baffles for fire-stopping and grease capture, and a containment volume that tapers to the duct interface.

o Unless this hood is much larger than it appears to be, I don't see it moving the 600 or so actual CFM it needs to move (probably requiring a 1000 CFM rated blower). I would expect that the pressure drop across the apparently modest mesh area at those flow rates to be high, requiring a blower with a large zero static pressure flow rate, and, unfortunately, likely a lot of blade tip turbulence noise unless some earlier suggestions are adopted to compensate.

o The style is pleasing.

o While best is the enemy of good enough, it is difficult without a test to determine whether a particular example of anything is good enough. Hence my view that to truly keep odor and grease out of one's house one needs a large overlapping commercial-influenced (given residential aesthetic limitations) hood design that in concert with the selected blower will provide excellent capture and containment with low maintenance.

kas

Thank you for the thoughtful analysis, Kas, that makes sense.

Indeed, my priority is performance. Which hoods would you say meet your standards for getting the grease and smoke out? Also, are manufacturer CFM ratings reliable or is that only the start of the story when it comes to actual performance?

I got this article off of the Vent-A-Hood website. This is where the term equivalent CFM originates. Please note the chart, too.

Vent-A-Hood® Range Hoods - Articles
How To Choose the Right Ventilation System
To help you chose the right ventilation system for your kitchen, we suggest you determine the appropriate answer to the following questions (listed below each question) to help focus your search. That is, finding the Vent-A-Hood® that is appropriate for your needs��"and identifying the size and blower specifications you’ll need when ordering. At the conclusion of this process, you will have matched your cooking equipment with the appropriate range hood. Note: Additional specification considerations may be required for outdoor cooking equipment.

What type of cooking equipment do you have?
o Standard electric
o Standard gas
o Professional style

What type of hood do you need?
o Wall-mount
o Under-cabinet
o Island
o Liner insert (wall-mount or island)

What size of Magic Lung® blower do you require?

There's no exact science for determining your blower requirements-if you never have all your burners on at once, you don't need to buy excessive capacity. To locate on the following chart the Magic Lung® blower that's appropriate for you, consider the type of hood you want, the type of equipment you use, and your cooking habits-whether you use all or only part of the BTU/WATT value of the cooking equipment. Note: Multi-burner cooktops are not generally operated at full capacity, whereas BBQs, woks, and griddles are often operated at full capacity.
Because the Magic Lung® uses centrifugal filtration units rather than conventional baffle or mesh filters, the Magic Lung® blower can handle cooking equipment with higher cubic feet per minute (CFM) requirements��"and can deliver equivalent CFM much more efficiently than other filtration systems. When comparing the Magic Lung® with blower units made by other manufacturers, use the “Equivalent CFM.”

What height hood do you need?

Whatever your kitchen’s ceiling height, Vent-A-Hood® can meet your needs. The bottom of a wall-mount or island hood should generally be mounted 30" above the cooking surface, but an under-cabinet hood requires less space (24"��"27" for a 9" hood, 21"��"24" for a 6" hood). Be sure to account for the height of anything that will be above your Vent-A-Hood, such as a soffit, a cabinet or a duct cover.
• 6" (under-cabinet)
• 9" (under-cabinet)
• 18" (wall-mount or island)
• 30" (wall-mount or island)
• Other.

What width hood do you need?

Wherever possible, the width of under-cabinet and wall-mount hoods should overlap the burners 3"��" 6" on each side. Island hoods must overlap by 3"��" 6" for proper performance.
• 30"
• 36"
• 42"
• 48"
• 54"
• 60"
• 66"
• Other.

What depth hood do you need?

The hood should be deep enough to fully cover all burners.
• Under-cabinet:
• 19-1/2" or 21" (standard)
• Other.
• Wall-mount: 24" (for standard and most professional cooking equipment),
• 27" (for some professional cooking equipment) or other
• Island hood: 27" (for standard cooking equipment), 30" (for professional cooking equipment) or other.

How do you need to duct your hood?
• Top vent��"the standard ducting location for all Vent-A-Hoods®.
• Back vent��"under-cabinet SLH6-K model and 30" tall wall-mount hoods may be top or back vented. Selected 18" tall wall-mount hoods may be equipped for back venting; this must be specified at the time of the order and additional charges will apply.

@HomeChef59.... Nice find..... Am I reading this right ??????

Vent a Hood themselves would recommend a least the 900 cfm Magic lung blower for most if not all 36" pro style ranges with a grill.

In fact they would pretty much recommend a 900 cfm Magic Lung blower ALL PRO STYLE ranges....of 36 " wide with 6 burners.

A 600 cfm blower would only be recommended for the VERY LOW end gas ranges.

That is of course if you believe that 900 cfm = 1350 cfm from other manufactures.

I've got the 600 CFM on a 36" gas cooktop. It sucks plenty good! I've had Best by Broan and Zephyr in previous houses. They suck pretty good, too.

Which one would I buy if I were doing all over again. Vent-A-Hood. It does a good job with the smoke and fumes. It does a great job with the grease. The technology is sound. The technology is old, but it has stood the test of time. My opinion only.

Just an observation, but the article doesn't push you to buy maximum CFM. Rather, they seem to be saying, use your judgment. Rarely will a home cook need to run all six burners at maximum high at the same time. It's a practical question. Do you have a grill? Do you have a griddle? If you do, you may need more CFM. If you don't, don't buy so much. They also urge you to buy a hood that is slightly larger than your cooktop. That's a good idea, too.

The chart clearly shows BTU banding. So do you go by that or just do what you think or are guided to as a ill informed customer.

The one good thing they do say is that wok cooking, grilling and griddle cooking will require more cfm. And yet the chart does not reflect a recommend increase in CFM.

This post was edited by trevorlawson on Tue, Jan 13, 15 at 20:04

Before I started planning my kitchen renovations, I never realized that range hoods were such a complicated subject. My requirements will be similar to the OP's, as I plan to install a 36" rangetop with a grill (probably Blue Star or Wolf). I can figure out most of the issues, but 2 area have me quite puzzled:

Baffles vs Magic Lung:

After suffering through the better part of a decade with an old Broan hood that constantly dripped grease, cleaning is a huge issue for my wife. For the past 5 years, we've had an inexpensive Kenmore Elite 400 cfm hood. Every so often a light goes on, we stick the mesh filters in the dishwasher and reset the light. So far, I haven't detected much grease under the filters, but we currently don't grill inside.

My understanding is that most commercial-style hoods have baffles and Vent-A-Hood has the magic lung. Every hood maker says that cleaning is simple, but I question those assertions after reading some of the posts here. I believe that the magic lung keeps grease out of the hood enclosure and ducts, but the motor needs to be disassembled and cleaned every year or so. Meanwhile baffles trap about 90% of the grease, but the remainder gets into the hood & ducts. So it's necessary to clean under the baffles every once in a while. Is this a correct summary? I was almost sold on Modern Aire, until I read a post about grease dripping out of it.

Make Up Air:

This has been discussed to death, but I haven't really seen any good solutions for those of us who live in cold climates. The only heated solution I've seen for a 1,200 cfm hood comes from Electro Industries. I'm sure this is very expensive but, more importantly, it requires an 80 amp breaker, which means I'd also need to upgrade my electrical service.

I purchased an inexpensive anemometer to see if I could get some sense of my house's leakiness. With the doors and windows open, my current hood measures between 690 - 740 ft/min over the strongest part of the air flow. I then closed everything, let the fan run for 15 min and measured again. To my surprise, the readings were essentially the same, so I guess this experiment isn't really telling me anything. Meanwhile my town's building inspector (who's usually quite strict) told me that he doesn't require make up air in residential installations. My current inclination is to just opening the windows for a while and see what it's like during the winter.

I'd appreciate hearing any thoughts that others might have on these topics.

The chart provided addresses the issue of equivalent CFM. That was the basis of the previous post. Trevor said he couldn't find the information on the Vent-A-Hood website. I found the information and posted it for your review.

Looking at the chart, I came to the conclusion most cooktops will need the 600 or 900 magic lung configuration. Some combinations will require the 1200. Each arrangement will require a calculation. It wasn't a difficult calculation to perform. I don't think this classifies me as ill informed.

A few years ago, I purchased a 36" six-burner Wolf range top, no grill, no wok, no griddle. I purchased a 1200 CFM Best by Broan vent hood. If I had purchased a Vent-A-Hood, I would have chosen the 900 CFM Magic Lung.

Add the total BTU's that each burner, griddle, wok or grill will produce. Check the Vent-A-Hood chart. It will tell you how many CFM will be produced at maximum usage. It also tells you to use the equivalent CFM calculation if you select Vent-A-Hood.

You will make an informed judgment as to whether you desire to purchase the maximum CFM calculation or if something less. In my opinion, no one operates at maximum. Something less, may be acceptable.

Any discussion of make up air is a different issue.

HomeChef59......Just to be clear, I was attempting to guiding my "ill informed comment" to dealers / sales people / manufactures reps coming to the GW and saying 600 cfm will be fine for a 36" range with a Grill and heavy cooking as stated by the OP.

Not actual customers who can separate the wheat from the chaff.

I edited the post to hopefully be clearer in my comment

I believe the rule of thumb is total BTUs divided by 10, adjusted up or down depending on the type of cooking you do and the location of the fan motor. A 36" Blue Star Platinum rangetop has about 100K BTUs total, so it seems to me that VAH's recommendation for 900 cfm isn't that far off.

With respect to VAH's claim that their hoods are equivalent to higher CFM hoods from other manufacturers, my understanding is that they're comparing their fan at the base of the hood to other systems with inline fans or fans at the top of the duct. It's not an apples-to-apples comparison, but it makes perfect sense to me that a fan collecting smoke at the source and pushing it out will be more efficient (albeit noisier) than a fan pulling smoke up from a distance.

In any event, it seems better to me to have a slightly overpowered hood that needs to be turned down, rather than have a slightly underpowered hood that can't keep up during periods of maximum smoke generation.

Am I looking at this correctly?

A lot of valuable information here. I actually went to a store today and listened to a Ventahood. It was quite quiet. For those of you who have worked with these hoods, can you comment on how Ventahood compares to Best, Modern aire, or other makes in terms of noise?

How does putting the blower on the roof affect performance? How about noise? There is also the consideration of annoying my neighbors with the noise if it's on the roof .... incredible how complicated this can get!

100k btus would put you smack in the middle of 1200 cfm.

This post was edited by trevorlawson on Tue, Jan 13, 15 at 21:27

Actually I wrote my post too quickly. This is from the VAH web site:

Because the Magic Lung® uses centrifugal filtration units rather than conventional baffle or mesh filters, the Magic Lung® blower can handle cooking equipment with higher cubic feet per minute (CFM) requirements��"and can deliver equivalent CFM much more efficiently than other filtration systems. When comparing the Magic Lung® with blower units made by other manufacturers, use the “Equivalent CFM.”

I have no idea if this is true, but intuitively it makes sense that baffles would reduce the air flow on other units. Also, shouldn't the location of the blower be taken into account when determining the size needed?

I've dealt with this multiple times here, so let me try again, no doubt slightly differently.

The VAH has a centrifugal blower that takes in air from the cooktop zone below it directly (no filtering) and blows it out into the exhaust duct. In doing so it has no pressure loss from filtering below it, but some pressure loss in interfacing with the duct, and certainly the usual amount from the ducting to the roof cap. In this sense it is more efficient (in air motion, not necessarily power) than the same centrifugal system would be with a filter in place. In any case, the flow rate in inevitably lower than the rated flow rate of the VAH hood by itself, and this can drop further with the house pressure drop due to inadequate MUA.

A baffled system using a different style blower has a pressure loss at the baffles (maybe 0.1 inch w.c.) as well as pressure losses in transitions and the usual amount in the ducting to the roof cap (which may be where the blower is actually located). In any case, the flow rate in inevitably lower than the rated flow rate of the blower by itself, and this drops further with the house pressure drop due to inadequate MUA.

So comparing these two options, one might say that the flow rate achieved by a VAH system will probably be a slightly higher fraction of its rated flow rate (not the magic equivalent flow rate), than the conventional system's achieved fraction of its naked blower's specified (zero static pressure) flow rate.

What we haven't taken into account is the VAH flow rate per square foot of aperture that it needs to assure capture and containment of hot effluent without effluent escape (I don't know this value), versus that for a conventional baffled hood, (which in my view is about 90 CFM per square foot of hood aperture). We also don't know the VAH fan curves which are essential for any HVAC analysis, even one with as many guesstimates as these undocumented components raise.

Hence, it is difficult to directly compare a VAH with a conventional system. Is the VAH significantly more efficient in air flow rate per unit electrical power? If it were it would be used commercially.

Is the VAH signficantly more quiet? This seems to be a contentious issue, and since I don't have a VAH in a comparable configuration to my Wolf, I won't make a specific claim. For one thing, it very much depends on the effort put into the fan blade design. Otherwise, a remote blower with an intermediate silencer should be quieter for the same flow rate given an assumption of equivalent air turbulence, which for the VAH is right next to the cook's ear.

In ca 2008 clinresga [I think it was] measured two systems, one a VAH, located in his two houses. The VAH was asserted to be noisier than a silenced remote fan baffled system, but no one has made a measurement of two comparable systems and reported it here recently. We might want to believe that VAH has improved its noise level, and I certainly won't claim otherwise.

Nevertheless, the statement from above: "Because the Magic Lung® uses centrifugal filtration units rather than conventional baffle or mesh filters, the Magic Lung® blower can handle cooking equipment with higher cubic feet per minute (CFM) requirements��"and can deliver equivalent CFM much more efficiently than other filtration systems. When comparing the Magic Lung® with blower units made by other manufacturers, use the “Equivalent CFM.” " is in my view incorrect,. Any properly configured hood blower system can handle the CFM requirements of the cooktop below it. It is just a matter of correct specification. And I would assert that equivalent CFM is not the way to analyze ventilation flow. The correct way is determine the pressure losses as a function of flow rate and compare the loss slope curve with the fan curve and find the actual flow rate at the intersection. (Wolf can provide some curves of this sort, but generally the loss slope curve will have to be generated by the analyst.)

If VAH were to proclaim that they could handle a given cooktop at lower cost, then we might have to dig into nitty-gritty design to determine whether that was always true.

I think that there are other questions hiding in the previous four or five messages, but I will have to try to deal with them in the morning. In the meantime, the various references that I raise in My Clippings would be good bedtime reading for those interested.

kas

Based on my experiences, apple to apple, for similar CFM and both internal blowers, VAH is subjectively much quieter than ones with baffle. It does not necessarily mean the db number is much lower, but VAH's noise is quite smooth and less annoying.

According to the specs, VAH 900 CFM (B200 + B100) can achieve 804 CFM SP@ 0.1", 725 CFM SP@0.2", 655 CFM SP@0.3".

Shimheric... That looks like good information.. but I have no idea what it means .......lol

It is the beginning of (the right-hand side of), and the most important part of, the fan curve. Thanks shimheric.

Are B200 and B100 separate blowers rated at 600 and 300 cfm respectively?

kas

Trevor, I just copied the numbers from their specs pdf. I am no expert, so I don't know what "SP" and " " " mean. But it looks like common terms for the trade in the field.

kaseki, yes. B100 can do 150 and 300. B200 contains two blowers. One is fixed at 300, the other is same as B100.

This post was edited by shimheric on Wed, Jan 14, 15 at 12:42

Comments on random questions above:

greasetrap; Baffles have to be cleaned, and this is also recommended for parts of the hood that either have become greasy or are where the baffles drain to. Quality stainless steel baffles can be cleaned in a dishwasher, although presoaking in a citrus cleaner solution may improve the job depending on how hard the grease has become.

W.r.t. the B200 + B100 fan curve. I just de-archived a Broan-NuTone curve supplied to my by Wolf for the 801641 blower rated on high speed at 900 cfm. The fan curve shows 920 cfm at zero static pressure, 900 at 0.1 inch w.c. pressure loss, about 870 cfm at 0.2, and 850 cfm at 0.3. This means not only is the Broan blower curve more vertical than the VAH curve (vertical is good), but continues more vertical to VAH's 655 cfm data point at more than 0.8 inches of pressure loss (equivalent to several stories of duct).

What this tells me is that it is possible to make a conventional blower (probably centrifugal, but not squirrel cage; I don't have this blower) that is more "effective" than VAH's blower configuration. The real take-away is that for cases where the duct and MUA losses are low, the VAH B200 + B100 is equal, but for more typical cases where duct and/or MUA losses are higher (and certainly baffles add 0.1 to this list - depending on flow rate and hood aperture area) the Broan unit is better. I see no justification in VAH claiming a factor of 1.5 equivalency, when their no-baffle advantage over baffles is slight and overcome by other factors in most cases. On the other hand, VAH no filter hoods will have an advantage over dirty mesh filters hoods with conventional blowers.

kas

more answers and comments to come

SP means static pressure. WC means water column, and is differential relative to the existing atmospheric pressure. (Recall your water column discussion in 8th grade science.) Pressure can be measured in inches of water column or in pounds per square inch or in pascals for metric units.

""" probably means inches. I usually write it out because of certain formatting issues at this website.

kas

I apologize if I missed a detail, but I skipped the VAH discussion above from the experts here.

As a consumer, I can offer you some experience. I don't believe MUA is required in SF (and is not in the general California code), but your jurisdiction may differ and things may have changed. Thus any system you put in is for your benefit. You may want to check out the simple damper from Broan/Best. You might want to check out the latest code updates, as things change constantly in the City and in California.

I went with Modern-Aire; the service and responsiveness from the local dealers (I went with Friedman's) and from the main office in SoCal was excellent. The price was also less than VAH for what I was seeking and the finish quality was higher and the leadtime for customization much shorter. Plus, it was an in-state company.

We too went through agony with my hood finalization, so I feel your pain.

Lumine:

The function of cooking ventilation is to capture and contain grease particles in the air along with water vapor and odor. The ducting and blower remove those components that do not get collected on the baffles or mesh filters or walls of the VAH blower unit. Smoke, odor, and smaller parts of the grease aerosol spectrum are usually blown into the atmosphere. It is the large particles that are collected. Different types and temperatures of cooking make the balance of these components different. No filter can collect everything, and in commercial settings is not usually expected to. In extreme cases, intense UV is used to breakdown the components of the exhausted effluent.

Note that the hood system does not suck up effluent from the burners. It captures rising effluent (which can move at 3 ft/s if hot enough) and pulls it though the baffles or whatever. If the effluent, which expands as it rises, misses being captured, it distributes itself in the room or house and some will settle out on the walls and furniture. The part that remains in the air will slowly be removed by the hood's operation replacing house air.

Hood system blowers can be in the hood, in series with the duct, or on the roof.

Silencers only silence what is beyond them relative to the cook. So they work with in-line and roof blowers, not in-hood blowers.

Exterior noise from roof fans is usually modest. I have to deliberately listen to hear my 1500 CFM roof unit from locations in the yard during a typical day. It might be more noticeable on a very quiet night with no traffic noise within a mile or so. However, I live in NH, not CA, and don't have neighbors' windows closer than perhaps 75 feet from the blower location on the roof.

kas

Thank you all very much for the replies.

75 feet from any neighbor is fantasy in San Francisco! I am lucky to have a fully detached house, most houses here are attached to neighbors on both sides :) My house has about 25 ft on one side and 10 ft on the other to the neighbors.

I am biasing away from the VAH hoods; they seem quite overpriced for what you get; the bulky appearance might not work well in my small place; and although it's superficial, I didn't like the controls and it just feels kind of dated. I am tempted to put a blower on the roof and go with one of the other makes, like this one from Moder-aire:

http://www.modernaire.com/modernaire/PMW-16.html

I am just concerned about noise but from what I'm reading here, this or something similar from BEST shouldn't be significantly louder than the VAH.

The damper valve for MUA seems like a nice, simple solution as well.

This post was edited by Lumine on Wed, Jan 14, 15 at 14:18

"Is the VAH significantly more efficient in air flow rate per unit electrical power? If it were it would be used commercially. "

I believe it is probably due to commercial setting uses external blowers. VAH's principle only works when the blower is internal since the grease is extracted by the blower itself. For very high CFM commercial applications, it would just make sense to use a remote high powered blower. On other other hand, if one opts using external blower, even VAH uses baffle, which makes the hood not VAH any more.

shimheric:

Agreed, in general. However, cost of electricity for air moving is a major cost for restaurants and commercial kitchens, and if there were a significant efficiency (CFM/W) advantage (and comparable fire safety), I would expect a company like Greenheck to use squirrel cage blowers of appropriate size for the ventilation task.

But I have to admit that like anything that might qualify as a system, there are numerous trades that have to be made for every aspect, and the VAH approach very likely optimizes in some trade space related to residential kitchen ventilation. It just isn't my trade space.

kas