Did I miss this answer, or can you not use the telescoping downdraft mentioned earlier? I think any of the ceiling options are going to look a little odd; a hood hanging down in the middle of that small space will be the first thing you see coming through the door. So my first choice would be a downdraft (if architecture allows for the venting), and I know it isn't considered ideal but perhaps there is one that will work adequately. My second choice would be to just let the ceiling ductwork be exposed. Surely the industrial look would fit in a rowhouse? Perhaps the ducting could even be painted. I am not sure what's possible... I have seen painted ceiling ductwork in public buildings, though possibly we are talking about different kinds of ducting material.

So it's been a while since I've needed to calculate head pressure losses in pipes, but you have to consider how many CFM your desired vent system is moving before you can calculate how many 90 degree bends will negate. That's why I suggested a remote fan setup since you can get higher CFMS that one that resides in the hood itself. 2. You'll need some kind of port to vent out of and they'll have a spring or gravity baffle to prevent critters from getting back up in. That's some static head pressure too. Piping diameter and type (flex, corrugated, solid) will affect airflow velocities as well. Flex pipes can do angle change sweeps (gradual) for a better flow than solid pipes. 3. You can get a hood microwave too. Even if you can't vent to the outside, a hood can be useful since they have grease traps. Sure you won't be venting heat or smell, but the hood will capture grease particulate and help contain it, rather than having it disperse all over your kitchen.

opaone opined. I think there is a fairly direct relationship between the baffle area, CFM's and noise. More CFMs for a given set of baffles (and constant baffle area) will increase baffle turbulence noise. However, baffle noise (generally a hiss sound) is not dominant unless a silencer is used with a remote blower. Otherwise, blower blade turbulence noise can be expected to dominate at the flow rates needed when cooking with hot pans (grease or oil near the smoke point). The larger the baffles the less the noise for any given CFM. I assume though that likewise the larger the baffle/CFM the less grease is removed? Two things are happening here. First, if the flow velocity near the baffles is not high enough, rising effluent will reflect from baffle surfaces and potentially escape from the hood aperture. Second, if the velocity in the baffles is not high enough, grease particles from the larger end of the particle spectrum will not be collected as well as they should be, causing them to pass into the ducting where they may condense on the duct surfaces. @Kaseki, do you know if there are any guidelines for baffle design/size/CFM for proper residue removal? Certainly those in the business of designing hoods and baffles will have design rules they use. I haven't come across any specific baffle design guidelines, but hood guidelines for use of particular baffles exist for those sources that produce baffles for commercial uses. Below are links to two example baffle (systems) with their pressure characteristics. (Links may need to be copied and inserted into one's browser.) http://productadmin.componenthardware.com/pdfRepository/repositoryFiles/20120906_025437_type%20i_product%20info_11-2011.pdf http://productadmin.componenthardware.com/pdfRepository/repositoryFiles/20120906_025211_type%20ii_product%20info_11-2011.pdf Baffles are going to be relatively simple on residential baffle arrays, and may have been experimentally tested and revised before production to yield decent effectiveness at minimal production cost. Are there trade-offs to that 90 CFM per sq ft aperture? EG, what happens if it's only 75 CFM? My simplifications are intended to avoid the extreme complexity of a problem space that can best be analyzed by computational fluid dynamics (CFD). What we have is a plume extent that has a shape, and associated with that shape is a velocity profile. The velocity changes with height and angle. When this plume enters the flow field close to the baffles, a lot of possible flow effects can happen, depending on the plume momentum and baffle details. There are also the tapered sides of the hood to consider as well as flat surfaces around the baffles. Picking the worst case plume velocity (~1.2 m/s) and demanding it be met by the baffle air velocity at the baffle gaps, and treating the plume shape (relatively bi-variate Gaussian) as a 10-degree constant velocity expanding cone for capture analysis seem to be adequate assumptions to avoid having readers later whine that their hoods were inadequate. 90 ft/min averaged over the aperture is just one of those approximations where the reality is that cooler cooking will require less, hence induction will require less than gas cooking due to lack of entrained hot gas combustion products in the plume, and in some cases will require more, except that the hood typically extends beyond some parts of any given plume thereby aiding containment of some momentum-degraded sideways drifting effluent near the baffles. Further, the overall air flow has some small capture influence beyond the edges of the hood entrance aperture, particularly for the lower velocity portions of the higher angle plume portions, and the overall flow over the cooking surface tends to move air toward the hood which also has some influence farther down for low velocity effluent. So, for many cases 75 CFM/sq.ft. may be adequate. Below is a copy of a table providing recommended updraft velocities for different cooking devices taken from one of the most useful of on-line sources, the Greenheck guide available at: http://www.greenheck.com/media/pdf/otherinfo/KVSApplDesign_catalog.pdf Note that this is for a 4-ft x 9-ft commercial hood probably 7 ft above the floor. Also note that there are various factors involved in using these numbers that may be found in the accompanying text. And of particular interest to me is that "wok" is listed with the "extra-heavy" category. This is probably applicable to Asian restaurant wok burners providing 100k - 200k BTU/hr gas jets. For residential wok cooking, the plume effects from the burner will be much less, but the temperature at the wok surface may be similar -- meaning that some parts of the plume velocities may be similar. So where should a residential wok be located in the table? I have induction for both cooktop and wok hob, and roughly 90 CFM/sq. ft. maximum air flow rate into my Wolf Pro Island hood, mounted at 34-inches over a peninsula, and it does a pretty good capture and containment job. Wall mount instead of island mount, gentle cooking instead of grilling or wokking, induction instead of gas, and other factors such as no cross drafts or an oversized hood may allow lower specific flow rates to be adequate relative to the table or others' experiences. Further, the reality is that for the most affordable MUA schemes, the inherent pressure loss will degrade the hood flow rate beyond that due to just duct and baffle pressure losses. So the renovator's task when contemplating 90 CFM/sq.ft. is to divine the degree to which my conservatism is overkill in the context of the entire ventilation system, kitchen layout, and cooking style, and design accordingly. kas

If it were my own home, I would have followed systems engineering process and analyzed the Hades out of the relevant subjects to be sure that what I ordered was all compatible, and then would have collected all components on site so final measurements could be made before ordering cabinets and placing electrical outlets. Perhaps needless to say, this has (and did have) the effect of greatly dragging out the reno. I would also have desperately tried to find a way to (a) use an exterior blower, and (b) find a place to put a silencer. And I would have to consider whether an 11 x 7 duct was too non-standard to contemplate. I have to assume for your home, eliasgrace, that your duct path is pretty fixed and there is no point in discussing variants. I think I would go with the squished 10-inch duct and then do the following: Tape all duct connections with approved tape See how well it works with more challenging plume generating cooking. Listen for how noisy it is Most importantly, not initially close up the access so that any vibration can be suppressed with techniques we can address later, and in any case, horizontal ducts should have a way to get into them if grease build up is detected, in this case possibly in noxious ways thru the cabinets. (Most of the time, residential grease not collected by the baffles is too sparse for grease drips out of the ducting, but plan ahead.) Some thinking about that now may save a lot of pain later.* You may wish to use a wood cover that is magnetically attached so it can be pulled off. If the blower is roof mounted, allowance should be made for having to upgrade it if flow rate is too low for full containment of the challenging plumes. If the blower is internal to the hood, then allowance for adding a roof blower is worth considering, although that could have electrical consequences. In spite of my comments above, I might be tempted to cut away the cabinets. However, this would change their structural strength without some additional structure that would have been much easier if added by the cabinet manufacturer. Replacing them would depend on their cost relative to the whole project. I'm not wearing your moccasins, so I fear that there is too little I know about all the details to assert that I know what's best. Last, let me note that your hood aperture is larger than my hood's 10 sq. ft. I use a 1500 CFM @ zero static pressure roof blower and 10-inch duct. It is adequate even without completed pressurized MUA (although it won't be if other exhaust fans are running so I still need it). Your actual specific flow rate (with all windows wide open) may turn out to be less than 90 CFM/sq. ft., and the impact on capture and containment will need to be closely observed. Fluid dynamics (applies to hood operation) is not linear or independent of the overall configuration, and general rules of thumb are merely ways of avoiding solving nearly intractable problems. What is your MUA approach? kas *Fantech makes some clamp unions that could perhaps simplify taking out a duct section.