Thanks for the posts. Yes, I was thinking that some sort of secondary filter, maybe a really open foam or some sort of deal was made to go on there. Especially after it says that on the sticker about cleaning the filter. Nothing according to KA. I've cleaned what I can, but not got into the fan blades or if there is anything slung inside the housing. There are no instructions in the manual about how to get in and clean it. By my looking I wondered about taking the screws out of the side and that bracket piece in the first picture, but then I'm unsure if the whole motor assembly would try to drop out! Flow wise I was just wondering if there was something like those foam filters they have for cars. Really an open type foam with large holes in it. Flows with little restriction, but would make the grease stay on it rather than go in the blower. Would probably have to clean the filters often as I do the baffles, but no one seems to know of any or any old part numbers etc. for older lines or alternate lines so far. Would have loved to have a roof top blower or perhaps a better grade vent, but just did not have the funds to do it. Saw blowers for about $1000 and then would have to buy the stainless vent housing, pipe etc. etc. Looked way over my budget. Got this one on clearance as they had a new model coming out. Don't remember what I paid, but seems like it was right at $900-1000 all done. Thanks for the posts. I'm going to try KA tech again and see if they have any suggestions (beyond pay a service person to come out and deal with it) on how the fans are supposed to be cleaned and some sort of secondary grease retainer. Thanks again for the posts. Any other info or suggestions still welcome!

Here are pictures which show what I mean. Some vent hood sizes require forgoing cabinets due to size and result in a matching piece of shallow cabinet wood or a pull up shelf above the hood. Btw, your vent hood and duct are very similar to mine. I have two 3 1/4" x 10" centered vertical ducts next to one another under the 42 inch hood. Rectangular ducts are less efficient in venting than round ducts, reducing cross section area from almost 50 square inch (7" diameter round duct) to around 36 sq inch for a 3 1/4" x 10" vertical duct. No wonder the original owner put in two (70 square inch total). Since your system is rectangular and vertical prior to its 90 degree turn, it may help if you measure the 'long' side (side facing cabinet and through soffit) and 'short' side vertical height (side on wall) to review with the vent hood company or HVAC company. There are specifications or exact requirements for each hood (specs). My vertical height is 52' long (directly behind the cabinets)and 30' vertically on the wall side (prior to the first large 90 degree turn). It's a tad more complicated to get all right with our rectangular duct design. Here is a link that might be useful: [Link:[(https://www.houzz.com/products/range-hoods-and-vents-prbr0-br~t_442)

I have a master bedroom closet area along a wall that is bisected by the chimney chase of a fireplace on the floor below, making a his and hers pair of closets. This is a triple-wall metal chimney surrounded by firecode sheetrock on the inside, studs, insulation, and sheetrock on the outside, including an access panel. It eats up about 30 inches of closet length. For a 10-inch kitchen hood duct with significantly less fire and access restrictions, you would probably loose at most only 20 inches. Many things are possible if the house design is recursively adjusted to accommodate all of the requirements. Do not rush the construction until you are certain that you have met your needs; there will be enough surprises even after everything seems to be defined. If you go to equivalent rectangular duct, you may still need to bulge the wall or otherwise ensure that there is not too much duct restriction. Rectangular ducts of equal sectional area to round ducts have a bit more pressure loss per foot. This should not be your first consideration, however, because you can find a blower with a fan curve suitable for the duct design, even if the duct path is tortuous. As for all of your construction questions, I'll have to ponder them when I have time, if I can understand them. In any case, if cooking is an important part of your life, then ensure that the kitchen design and the ventilation design are given the attention and space that they deserve. Unfortunately, it seems that your framing plan is somewhat past the point of easy revision. For others reading this: Please, please, PLEASE look into and solve all of the kitchen issues before finalizing a design and signing a contract. Comments on your bullet questions: - ?run horizontal through floor joists? YES - ?use rectangular duct vent when necessary? YES - ?Is it allowed to run near/along side the gas dryer vent? Not aware of any restriction on the moist air vent (note dryer vent has to be metal also. However, care to allow access for both, and particularly for the dryer vent duct for cleaning, is important.) For gas effluent vent, that should be determined by consultation with the architect, code officer, or gas company tech. Note: given a gas dryer, we are now in the regime of not letting the differential air pressure at the dryer fall below 0.03 inches, w.c., and make-up air performance or sealing off the gas dryer from the kitchen air is another big part of the kitchen ventilation design. - Run down into the basement if it can't run up? YES, but less optimal than up - Exit through an exterior wall rather than roof? YES - Best to get it in the garage and up into the attic and then up out the roof? Don't know about best yet, but it is a valid option. - best to have the range on wall A or wall B (does it make a difference)? TBD. Kitchen layout should account for numerous factors, of which duct location is only one. - assume need to use remote or in-line blower with any plan given its non-traditional route? In most cases, an external blower with an in-line silencer will be the lowest noise solution. kas

The duct size is determined by the manufacturer of the specific unit you select but it is likely to be 8" round which will fit in a 12" dropped ceiling or soffit. A round duct is cheaper and more efficient but in such a short run you could use a rectangular duct to raise the soffit/ceiling a bit. The duct could rise vertically in cabinets and then run horizontally to the outside wall. Your kitchen designer can easily accommodate that standard detail. I've never seen a range exhaust duct installed in a wall. I can think of no reason for a remote blower unless the sound of the fan at the highest speed (rarely used except when something is burned) is seriously objectionable. Most people run these fans at the lower speeds to reduce odors in other parts of the house. In my experience a remote fan is common in a commercial kitchen but very rare in a residential kitchen. If you are going to use a fan larger than 400 CFM, you may have to provide an automatic make-up air system. that would only be worth it if you have a very large, high capacity, semi-pro gas range or the room is unusually large. I would not terminate an exhaust at a roof if I could possibly do it at an exterior wall. It's not a matter of efficiency but avoiding roof leaks and snow & ice in northern climates. I try hard to avoid all unnecessary penetrations in a roof because wall penetrations are easier to waterproof. I would do option C because it puts the termination away from windows and on a less important facade. Also, the ceilings/soffits can be easily built at 8 ft. from the floor and there would only be one 90 degree bend, and it might simplify the cabinet design. Be sure to get rid of the attic access hatch in the ceiling of the closet. You wouldn't be able to use it anyway and it is contrary to building code requirements.