Rereading this thread in its entirety -- a trip down memory lane -- reminded me of some web sites with filters on their search function such that when one clicks on enough constraints there are no candidates left to purchase. feisty68's constraints have a similar effect. Thinking that maybe there is some way out of the box, two concepts come to mind to bring up: (a) One can choose a hood with internal blowers (as seemingly required) that has more specified flow than the external duct can handle. In this case, at full power the flow will be low, (or possibly zero, depending on the fan curve shape), but when run at part power to yield an appropriate flow rate for the duct, there should be reasonable flow. Whether this is adequate flow would require some analysis. At partial power the blade tip speed will be less and lower noise should result. For example, a VaH hood with two motor squirrel cage fan assemblies run at part power would likely still expel grease onto their housings as intended. Choked flow, however, may be sooner (CFM-wise) than a similar over-sized conventional blower / baffle system due to the nature of a squirrel-cage blower (as implied by VaH CFM vs. pressure loss data). I wouldn't want to guess which approach was louder at the power setting that was at the point of diminishing returns, CFM-wise. Related to this category is using an inline axial blower designed for higher pressure loss at the desired actual flow rate. Fantech might help here. Such blowers may be noisier, so an in-line silencer on the hood side of the blower might be essential. There are screaming-mimi aerospace fans that can push 1600 CFM through a six-inch duct. (b) The other concept is a hybrid exterior/recirculating hood scheme. I think both Best and VaH have examples of recirculating hoods. In this concept, if the actual systems are so configurable, the path to the filter pack would be split with one branch going outside. When the pressure losses of the exterior duct path rose high enough as blower power increased during heavy cooking, additional flow would be through the filter pack and back into the room. Some recirculating hood users here have commented on effectiveness and noise and their threads might be discovered and checked for relevance. Obviously, the simpler approach here is recirculating without engaging the external ducting. In that case, a separate soffit blower, soffit face register scheme could be used for further kitchen overall ventilation, helpful (slowly) when the oven is opened. kas

Thank you segesta & weissman. weissman - I can't vent outside from my high rise apt. :( I hope to finally get to see the Culinarian in the next week or so. If it's as good as everyone says, I can't see myself settling for lower BTUs. As it is, I hardly ever use the burners I have under 12,500 BTU. And even if I did go with 15,000 burners, I would still need 600 cfm's. segesta - yes, idiot software, but it is even more idiotic that their personal shoppers assured me I would get the rate advertised, and then their bosses refused to back them up. If I get a vent, I have to either give up the microwave or lose the counter space. And the reviews of recirculating vents on this site are awful. Tough decision. Can't an appliance co. develop a 600 cfm microhood that can withstand high heat ranges? The only microhoods I have been told can withstand high heat (well, 60,000 BTUs) are the Viking & Dacor, and both only have 300cfm. Doesn't make sense. There must be lots of apt dwellers like me who want a high heat range but can't vent outside!

i agree that 600 will be *adequate*. it won't be awesome or perfect. i have a 600CFM VAH over my 30" bluestar. 24" depth. it's more than adequate for most things, but when i stirfry, i do get quite a bit of smoke in the house. i don't stirfry all that often, so it's not all that big a deal for me, but if you do, you may want to consider going with more.

I have a Viking range and hood, and we love them. My gas water heater and furnace are in an attached garage, and I live in a mild climate area, so my situation is different from yours, BUT, speaking simply from the hood's operating efficiency, you need to have make up air coming from somewhere for the hood to work. Air is stupid, it will come from wherever available - leaks in the house, down an exhaust vent from a gas appliances, etc. Unless you get the model with the remotely mounted motor, the thing gets so noisy that you will rarely use it at full power. We're normally at half, unless we're cooking many smelly things. In those instances, the fan is on high, a window is cracked, and you can't hear yourself think but the exhaust works great. Stay away from the downdraft models - they don't work. I'm not saying they don't work as well, I'm saying they don't work. We had a friend get one based on a decorator's advice, we tried to talk them out of it, they now regret the decision. Easiest solution - use it on low or medium for most uses, and crack a window for the brief instances when you need really good airflow because you're using many burners or you need to exhaust stinky smells.