CFM needs for extractor fan

[shoengine]

I'm looking at making my own hood for steam and CO2 extraction. I was wondering what CFM I should be looking at to efficiently extract all the steam and CO2. Any recommendations on numbers I should be looking at? I assume this will have to be a bit more stout than a Broan bathroom fan.

 

[crazyjake19]

Lot of different factors come into play (batch size, duct length, temperature, etc) but for what it's worth I have a 250 CFM fan with 5 feet of 6" diameter smooth rigid duct and while it does OK, it's not nearly enough for my setup (4 gallon batches, electric, 3500 watt @ ~70% power). I should have gone with at least 400 CFM for my setup.

 

[Golddiggie]

IIRC, there was a BYO article years back that went into the math to figure out what CFM fan to get depending on how much ducting was between the source (steam side) and the final exhaust point. Part of that was the diameter of the ducting used. From what I can recall, you probably need more CFM than you think you do.

 

[shoengine]

I'm fortunate here for a few reasons. Namely, I don't have a system yet. Currently I'm BIAB in a propane fired kettle outside. I'm planning on moving to electric brewing at some point and adopting two or three vessel systems. I'm also fortunate because I'd be brewing in the garage and I removed a 10" chimney pipe so I have a large hole I can directly vent out with little to no ducting. Really all I have to worry about is drain management to avoid dripping.

I'll see if I can dig up that article. I'll determine what the max power output of my system could be (limited by 240 VAC 50 A service).

 

[sibelman]

My setup is similar to @crazyjake19 but a bit longer and with a jog in the path that adds some resistance. I went with a Vortex S-800 (711 cfm) and 8 in. ducting. It's more power than needed -- their 340 cfm 6 in. S-600 would probably suffice but I followed @Golddiggie 's "rule" of erring on the high side. A cheap fan speed control widget allows me to set the roar speed where needed.

 

[Golddiggie]

Going through all that is why I'm glad steam condenser lids are available now. Especially if you're heating with electric elements (which I am now). Since I have no propane fumes to deal with, I only need to take care of the steam produced in the boil.

 

[shoengine]

Going through all that is why I'm glad steam condenser lids are available now. Especially if you're heating with electric elements (which I am now). Since I have no propane fumes to deal with, I only need to take care of the steam produced in the boil.

That's certainly a possibility, but I'd need to work out what to do with all the water so that I'm not wasting it. Also, I have this huge hole in my roof...

 

[Golddiggie]

That's certainly a possibility, but I'd need to work out what to do with all the water so that I'm not wasting it. Also, I have this huge hole in my roof...

Some people use it for cleaning. I'm on a well, so doing something with it is far less of a concern.

 

[shoengine]

Fair. In the grand scheme of things it probably isn't much, but I track my water usage (as does the water company).

 

[Golddiggie]

When I was on city water, brewing never made enough of an impact to even worry about. Now that I'm on a well... Actually, the water probably gets returned to the well (eventually at least). So it's even better. Never mind cheaper.

You could always get some large containers/barrels and put it in there. Let it cool down and use it for irrigation (lawn, garden, etc.).