Thanks for your response. I am definitely not an expert on venting even though I've read a ton of threads about the subject.

The owners manual for the rnb says 300 cfm minimum, so is that suggestion way off? Why would they suggest it if it totally inadequate?

I don't do a lot of wok cooking, but I'd like to start. I do cook a lot and often have at least thee burners going. I can't say they are all full blast. I have five kids and cook at home all the time. I use mostly cast iron cookware and my Dutch oven on the top.

Thanks in advance

I'd say you'd need at least 600 cfm, which in some models of a vent a hood is 900 cfm equivalent. Seems like you do a lot of cooking and you will need something powerful. If you're used to no vent hood at all, like I was in my previous house, then even 300 will seem great. But to really use the bluestar the way it can be used (very high heat cooking, multiple burners going, lots of smoke and grease), you'll need something in the 900+ range.

I have a 1200 cfm bluestar hood and it works great. The hood is as important appliance as any in a kitchen.

I'd say you'd need at least 600 cfm, which in some models of a vent a hood is 900 cfm equivalent. Seems like you do a lot of cooking and you will need something powerful. If you're used to no vent hood at all, like I was in my previous house, then even 300 will seem great. But to really use the bluestar the way it can be used (very high heat cooking, multiple burners going, lots of smoke and grease), you'll need something in the 900+ range.

I have a 1200 cfm bluestar hood and it works great. The hood is as important appliance as any in a kitchen.

your blue star hoodâ¦is it loud?

i wonder if ventahood is really as quiet as they sayâ¦

Clinresga once reported here a sound test comparison of his Vent-a-Hood he had at one location and a more conventional system at another location. The VAH was reportedly much louder. A Google search based on this web site's URL and his name may find the thread. As I recall it was a long thread.

There are also threads about cleaning VAH that should be evaluated.

In my view and that of others, the 18-inch VAH mentioned above is too short front-to-back (depth) for serious cooking. One wants an approximately 24-inch depth to have overlap in depth as well as in width. With the added aperture, more CFM are needed to keep the air velocity up at the baffles (or whatever VAH use in their aperture because they use the squirrel-cage fans to perform one of the functions of baffles -- grease collection.

The problem with the CFM capability reported is that it is an apples to oranges comparison. Different things are being measured. It has been my presumption (giving VAH the benefit of the [great] doubt), that the CFM they report is measured for the hood and blower, while that for most fans and blowers is for the fan/blower alone without a hood. In both cases, when ducting is added and the make-up air (MUA) is restricted, the actual flow rate will be significantly less than the number associated with either the VAH or other blowers and fans.

What I would recommend for a 3 ft by 2 ft aperture is 6 x 90 CFM actual, and a factor for losses. Maybe (!) this is only 1.2 for VAH (with windows open) and 1.5 for conventional roof-mounted or in-line blowers/fans. It depends on too many factors to just throw out a number that will be valid, but the 1.5 is probably at least reasonably conservative given a decent source of MUA.

Under most cooking circumstances, you will be operating the fan at part power because this maximum flow rate won't be needed; the uprising effluent velocity will be lower than assumed for the "90" value. Sound level should be significantly lower. If you like quiet, then a roof fan and in-line sound suppressor with a baffle hood will be best, with most sound apparent to the cook being air turbulence at the baffles.

kas

In my experience VAH is comparable with other range hoods on high, but barely quieter on lower settings than on high. This is based on just one unit that I've worked with (where the duct immediately made a 90 deg turn then straight out the wall) so YMMV.