We have a 42" wide & 24" deep hood mounted 30" above our 36" cooktop. We're a tall family...ranging from 5'10" to 6'6" and still growing! So far, the only time anyone has hit their head on the hood is when my DH stuck his head up into it to check out the "squirrel cages" and didn't bring his head down far enough when he exited...he hit the back of his head! I don't think you should worry too much about head-hitting. Mounting your hood within the manufacturer's recommendations is more important. As to 1200 cfm, it sounds like you won't need makeup air b/c of the "California Cooler" ventilation. What some people don't understand is that the higher cfms have many pros: If needed, you have the higher power to remove anything from the kitchen (including smoke from burnt toast! yes, experience!) You will be able to run your hood on a lower speed more often and the fan will be quieter running on low or medium than on high. With lower cfm hoods, you may have to run your hood on high a lot more and the fan is generally louder than a higher-cfm's fan running at a lower speed w/equivalent cfms. The more bends you have to make in a duct run, the lower the actual cfms are. So, if you start out w/low cfms, any bends (or excessive distance) will lower the actual cfms even more.

clinresga: Thanks for all the info and good things to think about. I am glad to hear that you like the Fantech silencer. Our attic should easily be able to accomodate its size. Do you know if they reduce the effective CFM of the blower? (I hope to get off another project today and start calling various companies to figure out what we need). We will be using a custom surround - truly custom in the sense that our contractor/finisher will make it for us in any fashion we want. We haven't yet settled on a specific design, but it will be made of wood, painted the wall color and we'll probably try to make it "disappear" as much as possible. Ha! Given the nature of this project (restoring a 1920's remote fishing resort - off the grid and way in the middle of nowhere), we are working with a contractor who does beautiful work and can pretty much make anything out of any material. (You should see the cabinets he's made that look like they've always been there, the rock fireplace surround he built that is a deadringer for the 1924 one that came off in the 1970s, etc. He is a true artisan.) So for the range hood, we are constrained by the location of the refrigerator on the one side, and the size/depth of the range. I believe we will have a maximum of 43-44" for the surround (the stove is 40" wide and sits about 32" off the wall). It sounds like MA might be my first call if they can make a custom liner that is the right width and extra deep. We did hear back from the stove restorer, and the burners have a total of 72K BTUs (12K each) and the ovens have a total of 40K BTUs (20K each). I still think the FDK10 will work for us if we get to that level of pinching pennies, but we'll have to run the numbers to see! In another post, I saw you mention that you have a wall control for the blower and lights. Did that come with the MA? Or is it manufactured by another company? Are the blower and light controls on the same unit?

The most important duty of a hood is grease removal. But you don't want the grease getting into the duct, as it can catch fire. So, all hoods have to have some system for removing grease before it enters the duct. There are three commonly used systems: Baffles, mesh filters, and the VAH Magic Lung/centrifiugal blower system. The VAH system uses centrifigual force to sling grease against the sides of the blower box, where it is collected. It also creates a higher pressure area inside he blower box, which prevents fire from entering the duct (fire cannot pass through a high pressure area). THe downside to the VAH system is that the blowers have to run at certain speeds to make the centrifigual slinging effective. All pro kitchens use baffle systems. At higher velocities, they are effective without being too noisy. They work by having the grease particles run into the baffles as the air twists and turns through the baffles. The downside is that unless unough air is moving, they are not very effective, as the air just meanders through the baffle. Mesh filters are inexpensive and effective in smaller hoods. However, because of the smaller area of the baffle, and the mass of metal fibers in the mesh, they require more frequent cleaning and they are noisy or can even block airflow at higher air flow rates. As to duct size, you MUST use the size recommended by the hood manufacturer for proper operation. Changing from an 8" to a 6" duct almost halves the area of the duct, hurting preformance. Hope this helps.

Vent-a-Hood systems have an advantage and a disadvantage. The advantage is no baffles and hence no baffle pressure loss. The disadvantage is that the squirrel-cage blowers have a fan curve that loses flow rate with pressure loss faster than the radial and axial blowers used by others. Hence, use of VaH hoods is best done with short, straight ducting and low pressure loss make-up air approaches. For any serious hot cooking, you should plan to have 90 CFM per square foot of hood entry aperture, which you have not yet specified. With ideal ducting, the result would be met by a VaH blower just slightly more powerful than the result value. However, with more typical ducting and MUA pressure losses, the blower rating will need to be a larger factor over the requirement, possibly higher than the 1.5X I suggest for baffled hoods. Low noise can be achieved using a remote blower (external or in-line) with a silencer between blower and hood. All fans moving a lot of air per second when located next to the cook will be noisy. I don't own any magic VaH hoods, so I can't compare and/or contrast their noise levels.