I just finished struggling with the same issue. There seems to be a great deal of controversy about the magiclung and the ease of cleaning. I have spoken to some owners and they love them. As to their claim of their 600CFM being equal to other baffle or screen filter hoods rated at 900 CFM that appears to be valid based on two factors. First, there is at least a 20% loss due to the filters and second, many other units use a 7" or 6" duct further reducing their effective rate while VAH uses an 8" duct. All of these numbers are ideals that are never achieved in real world application so you have to take them as relative comparisons and not much more. I finally chose the Modern-Air duct as the best compromise as it uses an 8" duct, has an excellent reputation (made here in CA where I live) and very high quality construction and polished baffles with smooth rather than sharp edges. It was a little less than the VAH though that was not the deciding factor.

While I don't know this for sure, I would bet a few donuts that there is no residential code that requires as much air flow as you will want to have if you are doing serious cooking (defined as cooking with hot surfaces at or near the smoke point of cooking oils and grease). In my opinion, and this is close to what Greenheck supports for commercial use, an actual air velocity around 90 ft/min at the hood entrance aperture is desirable for the types of cooking one might do at home (with baffle filter hoods). This is equivalent to 90 CFM per square foot of hood aperture. If your aperture were 9 sq. ft., (and the hood was a baffle hood), you would need 9 x 90 = 810 CFM. To get this with a typical centrifugal exhaust fan and the pressure losses of baffles, ducts, and the MUA system trying to replenish this air flow, a larger than 810 CFM blower is needed. Without more information I recommend a factor of 1.5X, bringing the requirement to 1200 CFM. Now with a VAH, there are no baffles to contribute pressure loss, but there are all the other pressure losses. In addition, it appears from their data that the VAH blowers are less efficient at handling pressure losses. Adding complexity to this guesswork, the VAH entrance aperture velocity for full capture is unknown to me, and may vary with position under the hood. If I were you, I would use two of their double unit 600 CFM (nominal) blowers. Perhaps this can be viewed as a question of the risk of greater regret -- regret that 900 turns out to be too small, or regret that 1200 was more than needed. kas

This house was 1700sf, but I want to "age in place" so I added a first-floor master suite, laundry and a new kitchen. The stairs are narrow, without a handrail, so I didn't want to use the upstairs master (it's now my studio)! The person before me lived here 30 years and had one of those lift chairs until she finally had to go into assisted living. The old kitchen didn't have original cabinets and there was only 1.5 feet (really) on two sides of the island, the cabinets were only 1 foot deep and the 1980s fridge couldn't be removed without removing the island (width of the sink and dw only). The rooms are on a 12' wide scale. So, my new master and kitchen are 12'x12'. My previous home that my husband and I built was over 4000 sf on 4.5 acres. I was an avid gardener (and blogger). I don't have the gardening/blogging in me anymore. I have 1/2 acre here.

Generally, when hood ventilation system noise is described, it is at the position of the cook at the cooktop. Hence opanone's comment that an in-hood blower cannot be less noisy than an exterior blower, most things being equal. If the in-hood blower noise is compared to the external blower noise when standing at the open window, then the closest blower wins the most noise contest. As it happens, an external blower (and an in-line blower where space allows) can be configured to be larger than will fit in the hood, and run at lower blade-tip speed for the same CFM at the same pressure loss. I believe opaone is actually doing this. VaH use squirrel-cage blowers. Per their own flow vs. pressure data, they are best when the total pressure loss is low. The more conventional blowers such as Broan/Best, Fantech, and Abbaka sell, to name three of many, are better when the pressure loss is higher. Hood pressure loss for filtered hoods will always be higher than for the open base of the VaH hoods. However, that is only part of the story. The relevant pressure loss is that from the blower output to the outside and thence back into the kitchen via whatever make-up air paths are provided. When the ducts are significant, or the house tight with little MUA, or the MUA itself if filtered without its own blower, using a conventional blower is my suggestion for getting flow.