Just because a hood is sucking in air...and grease, doesn't mean it will all get sucked out. Grease is heavier than air and will cling. Better the grease is on the hood than all over your kitchen. It does require regular cleaning.

houses14, my Imperial range hood is not an insert, rather an under cabinet ss hood. However, the materials used, and the quality of construction, the fan motors, are the same with minor variances to allow for space restrictions within the smaller size of my hood. Construction wise, it is all that I had hoped for, was easy to install, and has functioned beautifully. Packaging and shipping were excellent. The ss is marine grade. This means that the amount of chromium in the ss will prevent rust from forming in the interior of the hood over time. The electrician informed me that their fan motors and switches appeared to be top quality. The warranty for my hood is 7 years, which is almost unheard of in the industry. Their specifications and installation instructions are right on to allow for optimal operation. For example, my duct is 8" from hood to roof jack and had to have a certain rise in height from the hood before the first angle in the duct work. Baffles remove and reinstall easily for cleaning. It was a joy to call Imperial direct with technical questions at their manufacturing headquarters in California. Someone was always immediately available to answer my questions regarding their vent hoods or recommended installation. My installer was promptly referred to their engineer for technical assistance as I requested that the wiring that would automatically turn on my hood once a certain temperature below the hood was reached be disconnected as I did not want that feature. To me, having that level of service available when answers are needed means a great deal. I found that the folks at headquarters were always honest even if it wasn't the answer I wanted and that they knew their stuff. Their light and fan switches are continuously variable which is rare on vent hoods. This means that they both function like a rheostat with a continuous increase, or decrease, rather than clicking up or down discreet notches, such as level 1 to 4. Also, I liked having the option of installing the switches wherever I wanted remotely, rather than being mounted to the underside of the hood. The hood easily handles removal of odors, steam or grease beneath it's surface. I've found that if the hood is allowed to run for about 10 minutes prior to cooking that it can be operated at a lower level and do a good job. The hood on low is fairly quiet but is noisier than I had anticipated at higher levels with having dual fans and baffles. Also, highest cfm level is 1000 which is a factor. However, I used a different size led bulb than Imperial recommended. I now have a gap around the bulb that needs to be filled with a rubber gasket. Also, the temporary roof jack is too large, and the correct one is waiting to be installed so the jury is still out on the noise issue. Noise level was quite an issue for me, but even if it remains unchanged, I would still buy the same hood given how pleased I am with the overall operation and that I can easily live with the noise that I now have. I'll have to look up the name of the online vendor I used and will add that information tonight.

The canopy wants to trap the rising smoke/vapor/greaseparticles, which we call "effluent" for short, and the effluent column expands as it rises. What that means is that as you increase the vertical gap between the stovetop and canopy, you need a wider and deeper canopy to get the same amount of effluent capture. You may also need a little more cfm. If not, as Momto says, some of the effluent escapes. How worried you are about that will depend partly on your cooking. If you do a lot of wok cooking and meat-searing, I'd be more worried about effluent capture. Also how close the kitchen is to the rest of the house, how sensitive people are to odors, how often you want to wash your walls etc. A lot of folks go for 30" or less vertical distance to get good capture, and say that they soon learn not to bump their heads. I went for a canopy just above my 6' height, but with 12" overlap on either side of the cooktop and a 9-inch bump-out from the wall. You will find *lots* of discussions of hood height if you search the appliances forum, as well as cfm and other issues. For example, makeup air is essential if you are venting a 60" Wolf, and will have a lot to do with how effective your ventilation is. This is new to a lot of people...

I have 6" of space between the widest part of my hood and the cabinet on either side of it. I didn't give much thought to how many inches would be best. I just knew I wanted some space between the cabinet and the hood. In retrospect I wish I had just done 4" because then I could have made the two narrow cabinets on each side 2" wider. I think 4 inches of space would have been fine. Some people will say that you need more space or the sides of your cabinets might get some grease on them. My kitchen is almost 5 years old now and there has not been one bit of grease ever on the cabinets by the hood. Here's how 6" of space looks with my hood. And here is a link to previous discussions about spacing between cabinets and hoods. Space next to hood