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Old 08-30-2011, 04:36 AM   #1
wittmania
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Default Vent hood and exhaust fan: Minimum CFM?

I just installed a vent hood and exhaust fan in my basement with the bright idea that I can brew down there when it's too cold to brew outside. I installed a 108 CMF axial fan (http://www.surpluscenter.com/item.asp?item=16-1260) and vented it through a 4" louvered dryer exhaust vent. It's only about 4-6" from the fan to the vent.

After I got all of this installed it occurred to me that I have absolutely no idea if 108 CFM is enough to keep the room free of Carbon Monoxide and the other nasty things that two turkey fryer burners would put off. Any CO experts out there that can tell me how to calculate the CFM I need in order to, you know, not die?

P.S. I'm not looking for any "I wouldn't do it if I were you..." replies. I appreciate your concern for my safety, but I'm trying to calculate what I actually need in terms of ventilation, and then I'll go buy a fan that can do what I need.



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Old 08-30-2011, 11:00 AM   #2
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I brew in my garage and had initially bought a 200-ish CFM duct fan from HD and it did nothing! there was condensation dripping from the ceiling and walls.
I upgraded to a Active Air 8" fan 720 CFM. I have it in line with 8" ducting out through a louvered duct on my exterior wall. I have it for the BK only and it is a beast! works great and is quiet.



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Old 08-30-2011, 11:40 AM   #3
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In the industrial world we would use something like 2000 cfm fan as a starting point and verify with a certified gas detector for oxygen and co content. I wouldn't use a turkey fryer indoors period, but if you must at least install co detector. You can get them at big box stored for like thirty bucks.

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Old 08-31-2011, 07:36 PM   #4
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I use the Votex 6" Inline Fan rated 449CFM and it works great. I brew on a electric system much like the one on this site. http://www.theelectricbrewery.com/

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Old 10-06-2011, 09:36 AM   #5
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The CFM will depend on how big is your basement is. If the basement is really large then you need to inject at least 400CFM. It's good that you found out that the CFM is not right.
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Old 02-26-2013, 07:31 PM   #6
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I realize this is an old post but it is exactly where I am now.

Interested in how bullywee finished off the Active Air 8" fan 720 CFM.

Called Braun to see what fan would be needed to vent a 5K CF garage (28x21x9) and was told an 800 CFM 10" fan. The model they recommended costs $400. THAT is not happening but the Active fan for $100, some duct work and inlet / outlet grills to cover the fan should work.

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Old 02-27-2013, 02:10 AM   #7
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From my research, the recommended ratio is 100 CFM per 10,000 BTU. I have a 3 burner system and use a 1,500 CFM Broan vent fan. It's kept me alive so far.

Keep in mind you need a fresh air intake or you may end up cause a negative draw on your furnace venting and suck exhaust back down your chimney.

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Old 02-27-2013, 04:40 AM   #8
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as a former weed grower I have many fans to vent with, and the Can Fan max line is my favorite, quite and efficient, and high powered. they are turbine fans, not centrifugal fans, and they are crazy powerful.



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