This is just a guess: I think if you meet the specs and requirements of the remote blower, you should be okay. The important thing is that the size of your duct is at least the size specified for the blower. You might want to confirm that with the blower's manufacturer, if they have a customer service 800#. If your duct size is too small (usually expressed in inches diameter), you will not get the full benefit from the blower, in other words, less than the 1000 cfm. BTW, are you sure you really need all that exhaust capacity? It's really a lot, the sort of thing suitable for a lot of heavy sauteing and grilling, cooking for a big crowd on a regular basis. With all that exhaust capacity, you need to plan also for fresh air intake to compensate for the negative air pressure you will be creating. Plan on having to open a window nearby or, if you really want to get fancy, build in an air intake device inside the venting system. I don't know exactly how they do this -- it's the kind of thing usually installed in restaurants. It's easy to go overboard when planning a renovation. You have to sit back and say, what do I really need, and what will please me?

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.

How big is the hood? What cooktop,rangetop,or range are you putting underneath it?

At the moment, I would call them concerns pending further information. First, do you have any combustion appliances connected, air wise, to the kitchen? Combustion appliances include furnaces, hot water heaters, and dryers. If they all have their own make-up air sources, then they don't count. Fireplaces count unless roaring hot and quite large, in which case they need their own make-up air even without any kitchen ventilation effects. One of two windows cracked open a couple of inches will perhaps achieve adequate make-up air for a quite low CFM requirement in lieu of wall cracks and other dusty paths. Bathroom exhausts and dryer vents should have dampers that will not allow enough MUA for any purpose. Gas fireplaces are required to not have dampers, so only the doors limit back-drafting. That is also an undesirable path. 300 CFM, for example, is 5 cubit feet of air per second. This would require more than a couple of inches of window, even if unscreened, to avoid an undesirable pressure drop in the house when combustion appliances are present. It will certainly degrade the flow rates of the kitchen ventilation blowers, more so with VaH squirrel cage blowers used in Magic Lung systems. What are the claimed CFM of the VaH inserts you are using? (Zero static pressure values not Magic Lung claimed equivalent values) What is the area (or dimensions) of the air intake aperture at the bottom of the hood assembly containing the inserts? Is there some overhang of the overall hood relative to the entry apertures of the inserts?