@catinthehat fan curves? like the graphs you mean?

Yes the graphs =). The graphs tell the full story. For example, you can buy a large room fan at Home Depot for 300 bucks that will put out 5500 cfm. Why so cheap? Because that same fan will barely work when it has to pull that same amount of air under frictional forces. Fans in ducts have to work hard to move air because the ductwork "drags" on the air, making it harder to move. House fans sitting in rooms barely have any pressure drop to account for. Fan curves tell you how much air a certain blower will actually pull given a certain pressure drop. The flatter this curve, the more powerful the motor and more that fan will perform closer to its rating. The Prizer blower is significantly more powerful than the other two options you listed, and barely loses cfm as your pressure, or duct length, increases. Hope that helps! It gets even more complicated than that, but this analogy should be sufficient to get the big picture.

@catinthehat that's great to know, do you have a link to these curves that I can checkout? I'd like to see what they look like!

I'm just following to see what you find out.

I've had the Prizer roof mounted blower for about 5 years now. Having not had any others, I can't compare. Due to my roof over the kitchen area, my duct run is only about five or six feet, so I can definitely hear the blower. I rarely use it on high, medium or low takes care of most cooking.

@cookncarpenter Hear it like you can tell it's on? (like say an external heat pump unit) or hear it like you can't have a conversation in the kitchen when it's on?

Can't help you on the blower, but I installed an inline blower, was not thrilled with the noise, and then got a Fantech silencer muffler, and that made a dramatic improvement - well worth the cost. https://www.amazon.com/Fantech-LD-8-Silencer-Duct/dp/B00073IO2Q/ref=sr_1_4?ie=UTF8&qid=1523672896&sr=8-4&keywords=fantech+silencer  note the link is to an 8 inch silencer, based on your cfm, you would likely go with the 10 inch size, or even larger if they have a 12 inch.

catinthehat: Do you have a link to the CFMR1400 fan curve? I couldn't find it in a quick search.

Thanks

@kaseki - if it exists, they don't publish it online, I spent hours searching for it

We have the Abbaka and are very happy with it. It's quiet outside the house too, which was a consideration given that it's located near our deck. I'd second the recommendation for a silencer. Here's [a link[(https://www.houzz.com/discussions/help-which-hood-zephyr-monsoon-ii-or-best-dsvw-vd~4849683?n=2) to some other comments about it our adventures in fan.

Hi @kaseki and snafu,

sure no problem:

https://www.bluestarcooking.com/wp-content/uploads/2015/12/BlueStar_Designer_Hoods.pdf

I believe it's on page 16. They plot their curve with equivalent lengths so you'll have to do a standard friction loss conversion.

catinthehat what are your thoughts on Prizer vs ModernAire? Which one is better? I will be getting a 36" Bluestar gas range / rangetop.

Hi Ria!

Their website gives no information on their blowers. I just emailed them asking for their blower curves for their 1400cfm external blower. At their price point I’m assuming you don’t want a noisy motor inside the hood. Will post the results and comparison!

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I may have failed to notice catinthehat's response of April17, 2018 because I don't see a response from me. Thanks for the link.

Ria Raj: The fan curves by duct length can be converted, but either way don't tell the critical part of the story -- what is the pressure loss vs. flow rate of the hood with baffles in place? This pressure loss may be expected to dominate duct loss when using 10-inch ducts at the 1400 CFM blower's full power, even a 100-feet's worth. And that assumes no MUA pressure loss, which will certainly exist, even with a sophisticated active MUA blower system. I still recommend assuming a 2/3 of rated actual flow rate when all of the variables are not known, and using that value divided by the hood entry aperture area to achieve roughly 90 CFM/sq. ft.

My asserted hood rule is: Overlap the cooking plumes to achieve good capture, get the velocity in the baffle gaps up to roughly the highest plume velocity, ca. 180 ft/min. (With induction one might squeak by with a bit less due to lack of a gas flame aiding the upward velocity of the plume.)

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