thanks for the input.. I found the deal through kitchen foundry. I don't believe it is a floor model. from what I am told it is just new old stock. from the link weissman posted, people weren't complaining about the quality nor the performance. that was my main concern. people state the finish comes off the baffle boxes over time. after talking to Erik from kitchen foundry he stated that is mainly due to harsh cleaners people are using..... and worst case they can be replaced for 170 bucks. the other complaints were noise, but most seemed to state it was due to improper install or unbalanced fan wheels. My only real reservation now is the fluorescent lighting. I plan to look into an LED tube replacement. This post was edited by Zivman on Mon, Jan 20, 14 at 21:22

The problem, besides using the term magic (a usage that should send everyone running away) is that all fans have a varying flow rate (cfm) with pressure drop across the fan. Most fans sold separately are rated for the cfm they move hanging in the air (zero pressure drop). A quality fan manufacturer will measure and supply the "fan curve," a plot showing the relationship between cfm and "pressure loss". When a hood is sold with its fan, the flow rate will necessarily be less than for the fan hanging in the air. (A factor of 1.5 is a bit bold, though, in my opinion.) Very likely, if they aren't lying, VAH is claiming that if the fan were unrestricted, it would achieve 900 cfm flow. Of course, a 900 cfm Broan fan, put in series with a hood and reasonable ducting, might only pull 600 cfm also. However, I don't think VAH is counting any ducting, so comparisons are difficult. If VAH are tying to claim that their fan design has a more "robust" fan curve due to the blade design, then they should supply a fan curve that supports that intent. I doubt that a squirrel cage design is as good for that purpose as a backward curved blade axial fan, but I've been hopeful that VAH would some day provide useful information. (I'm also hoping to find a winning Megabucks ticket.) I think it best to consider other factors such as noise, cleaning ease, etc. VAH is often touted by appliance sales persons, and one wonders whether the mark-up is higher for VAH than for competing suppliers. kas

Somehow, this thread went on for years without a mention of make-up air. Assuming a hood with sufficient flow rate, particularly for the larger cooktops, make-up air is another significant expense and (for an existing house) potentially an architectural pain to implement. Also, the claims of the VaH sales lady that the centrifugal extraction process of the squirrel cage blower removes ALL of the grease particles is beyond suspect. If it were true, the configuration would be a great help to commercial kitchens that have to pay to have their ducting inspected and cleaned once a year. It is true that the extraction efficiency is a function of the rotational air velocity, but the finer particulates would need something like a turbocharger impeller ( > 100k RPM) to be affected). Also, the VaH wheel is not moving extremely fast; if it were, then the acoustic noise from the air turbulence would certainly exceed that from the supposedly less effective baffles, yet in the testimonies above the VaH fans are described as quiet. The plot below shows a baffle example, and I would yield on any assertion that a squirrel cage blower could have a different extraction efficiency curve. But I won't yield on the claim that the VaH embodiment is 100% effective. The way baffles operate is to remove the larger particulates that would settle or impinge on the duct surfaces and hope that the remaining particulates would be expelled into the outdoors. There is a factor often overlooked in that commercial systems have external upblast blowers, and these can also perform some centrifugal grease particulate removal of their own. Wolf/Broan and Abakka down-roof centrifugal blowers may also achieve some effect there, but at that point the grease is outside anyway. One other comment on VaH squirrel cage blowers: These blowers are more affected by duct and MUA restriction than conventional blowers. They start out with the advantage of no baffles (this is a significant pressure loss in a conventional system), but when an entire system, including MUA is evaluated, VaH will start to lose advantage with added ducting or insufficiently controlled house pressure. Last, I want to remark on the claim that commercial hoods have vastly more airflow than residential hoods. What is important for containment is the velocity of the air entering the hood. If 90 ft/min is achieved, the Greenheck Guide table copied below suggests sufficiency for most residential cooking. One difference is that commercial hoods, which are very high, typically have only one bank of baffles, so the air velocity in the baffle slots can be two or three times that of a typical Wolf hood, say, with its expansive baffle arrangement covering the hood entry aperture. This will improve particulate capture somewhat.

I can't answer most of your questions, but . . . None of the major hood manufacturers recommend having the hood that high over the counter - 30" is recommended and 36" is maximum, usually. I'm 6'1" and we originally thought 36" would be too low, that it would get in the way of cooking. When it was framed in it looked WAY too high, so we lowered to 36". I would suggest you go with the manufacturer's recommendation and not go any higher.