Strange that these sources are promoting a liner that is smaller than the actual cooking zone. Perhaps they haven't discovered that cooking plumes expand as they rise, and hence hood overhang of the cooktop is needed to capture the effluent entrained in the plume. Some of my thoughts on this matter are published above, and in other threads here. I would consider the 40-inch liner necessary, at a minimum. (One cannot always get any particular size one might want unless it is made to order.) Also worth noting is that the higher the hood is mounted, the wider (and deeper) it should be to ensure capture.
As noted in messages above, for good containment after capture, the actual CFM should be close to 90 CFM x hood aperture area in square feet, and in this case the aperture dimensions may expand to the inner dimensions of the liner cabinetry, depending on details of the shape that results. Rated CFM should be roughly 1.5 times this value to compensate for pressure losses affecting the actual flow rate of the blower. These are pressure drops going from cooktop to outside and then back inside measured at the desired air flow rate. To keep these losses to a minimum, some make-up air approach has to be defined and incorporated.
(Many factors affect both the 90 value and the 1.5 value, and these are only generalizations based on approximations. They have, however, worked for me, and seem consistent with information published by the commercial cooking ventilation specialist Greenheck. These values should lead to ventilation that is sufficient for most, overkill for some, and insufficient for few. In my view, money plus a little extra that may lead to modest overkill beats spending the money and finding the result unsatisfactory.)
Make-up air (MUA) is another whole topic that is nonetheless essential, and usually not negligible in cost. Please search for and review other relevant threads for background and then ask questions.
For lowest noise, a silencer (if it will fit) should be in the duct path between the hood and the exterior or in-line blower. If the motor is adequately balanced, blade tip turbulence noise should be the loudest noise, and this can be reduced with the silencer. Baffle turbulence noise should then dominate, and be tolerable for normal conversation next to the hood.
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gold cabinet hardware and chrome faucet
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