The reason you are getting conflicting advice is because of your 10" duct. Your builder recommends the Wolf line because the 1200 CFM and 1500 CFM blowers connect to 10" duct. However, this will be noisier than the Vent-A-Hood when connected to 10" duct. Therefore; your salesperson, who appears to have been listening to you, is aware of the noise factor in your situation and recommends a 900 CFM hood. Vent-A-Hoods are very quiet but 900 CFM is not enough to ventilate a range with a griddle and a grill. They'll both perform okay, but you may not like the noise from the Wolf and probably won't like the power of the Vent-A-Hood. Your situation requires adequate ventilation and quietness. A different Vent-A-Hood, with a 1200 CFM rating instead of 900, would do both, but you will need to change out to a 12 inch duct. The size of the duct is a determining factor in overall noise of a hood. Larger is always quieter and the extra 2 inches decreases noise by about 30%. Your builder does not want to redo this and the salesperson is selling to what is already there. There could be an X factor. The Vent-A-Hood, although you won't have to clean it often, requires you to reach up into the shell and detached the box around the motors for cleaning. Not knowing your health or what you look like I don't know if this is practical or not. Your builder may know this and recommends the Wolf for that reason. But, your 6-3 husband can certainly do this task then. IMO, when comparing these two lines, go with a 1200 CFM Vent-A-Hood, utilizing 12 inch duct.

In principle, any hood with an internal blower could be gutted of the blower and operated with an in-line or roof mounted blower. (GreenDesigns may have meant that using it while leaving the blower inside would be a poor plan.) I can imagine construction details that might cause non-optimal internal hood flow patterns, but I have no detailed knowledge of the internal construction of myriad hoods to know whether such are prevalent. There may be nanny jurisdictions that would claim that code approval of the hood was violated when it had its blower removed. Any hood available for order without a blower likely is fully compatible with an external blower. This, of course, can be confirmed with the manufacturer. The most important adaptation requirement is that the blower be continuously controllable, and that the hood control be a continuous motor control. A hood with just a few motor speed positions on a switch might require a compatibly-wired motor. While a multi-position hood control could in principle be replaced by a continuous control, par. 2 may apply. When I was doing my kitchen reno, I chose a compatible hood/roof blower combination (supplied by Wolf) because the entire scope of the project (gutting and reconstructing part of a house) made playing with the details of the blower circuit a side project of tertiary importance that I couldn't afford the time to deal with. As it happens, inside my Wolf (Independent) hood is a diac/triac motor control circuit, about the simplest design available that goes back to the '70s. The compatible Wolf (Broan) roof blower uses a typical induction motor that is easily controlled by this type of circuit. The cost versus time value trade-off needs to be considered when dealing with issues like this. kas

Thank you for choosing the Appliance Forum. We hope to meet your needs. Air flow rate (CFM) requirements are not determined by the area of the room when the subject is cooking ventilation. Cooking ventilation works by capture and containment of the rising and expanding cooking plumes generated by the hot cooking surfaces. Hence there are two essential performance requirements: Capture requires that the hood overlap the expanding plumes. The plumes have various shapes and speeds, but for convenience we treat them as conical from each point on a hot cooking surface, rising upwards over a range of angles from vertical to ten degrees from vertical. This leads to the capture requirement of having the hood overlap (as much as practical and affordable) the contour of this distribution of cones, at the chosen height of the hood aperture. A three-inch hood overlap of the cooktop is often mooted as a simple version of this requirement, but in some cases is inadequate for full capture. Containment requires that the blower flow rate be high enough to ensure that the effluent in the plumes is moved to the interior side of the baffles and expelled from the house, with none allowed to reflect off of the baffles or other hood parts and escape from the hood. The nominal air speed that I suggest is adequate for residential cooking is 90 ft/min over the hood entrance aperture. 90 ft/min is equivalent to 90 CFM per square foot of hood aperture. Other points: The rising plumes can have a velocity of up to 1.2 m/s (somewhat less for induction) so the containment air velocity is used to block significant downward reflections at the baffle surface. Your two hoods should be treated independently as to requirements, except when make-up air (MUA) is addressed. I"m going to skip that subject in this message. Most importantly: Blowers are rated at zero static pressure across them, i.e., hanging free in the air. This is not the situation in the kitchen ventilation environment. Skipping the discussion of all the reasons why, I suggest you choose a blower that is rated at about 1.5X the intended actual flow rate calculated from the 90 CFM/sq. ft. requirement. Else, a more elaborate analysis is needed, and the MUA system is involved. This makes it somewhat recursive to perform. For a given flow rate, blower noise is reduced by using large blades moving a low speeds. (Consider the Casablanca fan, for example.) So it is true that a higher rated external blower will, at a setting below its maximum, be quieter than a smaller rated external blower running full speed. Typical Wolf/Broan or Abakka blowers mounted on the roof will be quieter than the baffle hiss if silencers are used in the duct path. In your case you will want two blowers and individual ducts, I think, with individual silencers. MUA comments follow in next message. kas

Ideally the hood should be 6" wider than the range. I think the recommendation above to go 12" wider than a 30" range is overkill. "reasoning was something along the lines that with a bigger hood, you can install it a little taller (looks better) than the recommended distance between stove top and base of hood." Either you misinterpreted what you read, or the person who said that is misinformed. I think what you are referring to is that a taller canopy-style hood will gather and contain, i.e., capture, the smoke and grease better than a more sleek-looking flat glass hood for example, or the smaller undercabinet hoods that are 3-6" tall. In addition, a taller hood has more of a wow factor and presence in a kitchen. I would not equate a taller hood to being able to install the hood a greater distance above the range. Also if you install a hood too high above the range, the proportion can begin to look odd. Most of all, installing the hood too high above the range gives the smoke and grease more opportunity to escape. You wouldn't want to spend all that money on a hood and then curtail its efficiency by installing it too high. The ideal height is a 30-36" distance between the top of the cooktop and the bottom of the hood. I didn't see any mention in the OP of exhaust duct size. Duct size is important. You could buy the best hood in the universe, but if the duct is not sized appropriately, the hood will have decreased efficiency and increased noise through no fault of its own. The most common required duct diameters are 8" and 10". The hood's specs will say which. For a 30" range, the 36" hood will most likely require an 8" diameter duct. Hoods that require a 10" duct typically are for 48" ranges or larger. Do NOT give in to your builder if he says "I am sure a 6" duct will be fine". That might be an easier installation for him, but you have to live with it.