1) Make sure your carpenter makes the wood surround / hood bigger than the sizes of the insert. so if your insert is 34" x 22" make the hood 36" x 24" ish if possible or even bigger. 2) Recess the insert 6" up into the cabinetry to create a larger capture area. Think of this as an upside down sink, the insert is the plug hole and the bowl is the wooden frame. The bigger the frame the more smoke and grease will end up going out of the house. 3) Insulate the gap between the wood and the insert. 4) If possible make 2 x 45 degree turns above the hood instead of 1 x 90 degree turn, this will reduce noise and friction.

Front to back depth should achieve the same capture goal as described for side to side. Sometimes a hood can be mounted farther from the wall and a spacer applied at the back, thereby achieving a somewhat deeper effective hood. Effluent will curl off of a flat back spacer. If flow rate is high enough this effluent will still be captured as it can't escape into the wall. Alternatively, the back spacer can be angled between the back wall and hood entry to reflect upward. Keep in mind as you think about this that the plumes have velocity (more than a meter per second in some cases) and momentum. Momentum is conserved on reflection (accounting for angle of reflection equals angle of incidence relative to the normal, just like light), but overall momentum is degraded by friction with the air and enhanced when entrained in the hood flow. Cooktops and ranges placed against walls with counters on both sides and cabinets above them that drop down below the hood provide a certain degree of flow support as the air is somewhat channeled to the hood and the plumes are somewhat restrained at the sides. Along with an excess of air flow (relative to my suggestion above), you may find that most of the plume is still captured. I have an island configuration so I can only surmise the flow patterns that will likely occur, as informed by various schlieren photographs of commercial hoods that have been published. Hoods can be at any height, but given the plume expansion, have to grow in size the higher they are placed. Commercial hoods often have their apertures at 7 feet above the floor (four feet above the cooking surface), and are built commensurately larger and have appropriately greater air flow (and MUA to replace it). You want the hood to be high enough to avoid head interception, as well as high enough to provide clear sight-lines to the interior of pots. I recommend drawing a side view sketch to scale of the cooking configuration, and add a stick figure cook. Observe sight lines and head vs. hood as the figure bends at the waist. This lends itself to experiments with hood mounting, both in height and offset from the wall. My Wolf pro island hood base is at 34.5 inches above the cooktop for a variety of reasons, and it just clears my head. Hoods that don't extend so far out may still miss one's head due to bending effects. At worst, head interceptions will train the cook to avoid the hood. :) At max power, the zero static pressure flow rate is 1200 CFM. Mounted In the hood, duct, or roof with pressure losses from baffle restrictions, hood transitions, duct losses, and in particular imperfect MUA, the actual flow would likely be closer to 800 CFM. This is higher than the 560 or so nominal flow rate needed for your newly described aperture, so you should have some margin unless the MUA is inadequate, in which case the house pressure will drop some and the flow rate from the blower will match the MUA that results from the MUA design and the pressure the house drops down to. Carbon monoxide sensors become desirable in such cases if there are combustion appliances in use. kas

Stainless steel easier to wipe down than wood. Also, it’s more of a pain to buy the separate components for a hood with cabinetry surround than a metal hood where it comes all-in-one. Also you need to make sure that the cabinetry surround is designed with proper proportions. A metal hood, you just shop for the one with the correct measurements. For a cabinet hood surround, you will have to carefully examine what the designer‘s hood surround plans are. It needs to be 6” wider than the cooktop. It must be deep enough front-to-back which is at least 24” deep; a common error of cabinet hood surrounds is that they are designed too shallow. Also sometimes a cabinetry surround plus a wall of more upper cabinets all around it can look like too much wall of cabinetry. Depends on the design.

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?