Question Relating to Ventilation (CFM) Requirements

[IowaHomeBrewer]

Hi All,

Recently built my indoor electric brewery, went with a BIAB solution from High Gravity.

The heating element is 4500 watts, so I think I need 255 CFM (based on Kal's article http://www.theelectricbrewery.com/ventilation).

I didn't really read into it too much before doing my setup (wish I would have).

I built a frame for a normal range hood for a stove and installed one there and vented it outside. I think the fan included is at 90 CFM.

As I brew, I see the steam all leaving but the condensation collects on the range hood and dripped back into the boil kettle. The batches I've brewed are still fermenting, so its really hard to say how it impacts the beer but I'm sure there will be an impact.

Obviously I need to bump up the CFM.

My question is, do the CFM values stack? Example, if I install a 190 CFM inline fan in my ventilation ducts and keep the 90 CFM fan on the hood, and both are active, is my CFM rating at 280? I ask this because I see fans for 190 CFM for like $30, but a fan for $255 adds significant cost and I'd like to keep cost down so my wife doesn't disown me.

 

[dmcman73]

Hi All,

Recently built my indoor electric brewery, went with a BIAB solution from High Gravity.

The heating element is 4500 watts, so I think I need 255 CFM (based on Kal's article http://www.theelectricbrewery.com/ventilation).

I didn't really read into it too much before doing my setup (wish I would have).

I built a frame for a normal range hood for a stove and installed one there and vented it outside. I think the fan included is at 90 CFM.

As I brew, I see the steam all leaving but the condensation collects on the range hood and dripped back into the boil kettle. The batches I've brewed are still fermenting, so its really hard to say how it impacts the beer but I'm sure there will be an impact.

Obviously I need to bump up the CFM.

My question is, do the CFM values stack? Example, if I install a 190 CFM inline fan in my ventilation ducts and keep the 90 CFM fan on the hood, and both are active, is my CFM rating at 280? I ask this because I see fans for 190 CFM for like $30, but a fan for $255 adds significant cost and I'd like to keep cost down so my wife doesn't disown me.

You will always have some condensation collecting on the range hood no matter what the CFM is. The way to fix this to make a "channel" (sort of like a gutter) and the edge of your hood all the way around then in one corner or end, drill a hole, attach a vinyl tube and insert the other end into a sink or a bucket to collect the condensation. That will keep any of the condensation from dripping into your wort.

Is your hood round or rectangular/square?

EDIT: It doesn't hurt to bump up that fan either, this is the one I have and works great: http://www.amazon.com/gp/product/B002JQ14F8/?tag=skimlinks_replacement-20

 

[IowaHomeBrewer]

It is a rectangular hood, think of something you'd see over a normal stove in your kitchen, just vented outside.

There is a little gutter, but the moisture collects everywhere. The moisture that collects on the fan housing itself is what drips into the kettle. Most of the moisture collecting on the range hood itself does go into the gutter and drains out like normal.

 

[kal]

As I brew, I see the steam all leaving but the condensation collects on the range hood and dripped back into the boil kettle. The batches I've brewed are still fermenting, so its really hard to say how it impacts the beer but I'm sure there will be an impact.

I wouldn't think so. It's likely only a few drops here and there. The bigger impact is the steam the room. The main reason to properly evacuate the steam with a properly sized fan (and to replace it with make-up air) is to avoid too much condensation inside the house/building.

My question is, do the CFM values stack? Example, if I install a 190 CFM inline fan in my ventilation ducts and keep the 90 CFM fan on the hood, and both are active, is my CFM rating at 280?[/quote]
No, not really. While it depends on the types of fans, the CFM may even be limited to the lowest fan (think of two people driving at different speeds on the highway - if someone in front of you is going slower you need to slow down too).

Note that CFM in many cases is theoretical. As soon as you add any amount of ductwork to some fans (especially simple stove hood fans means to directly vent outdoors), the CFM can drop drastically. This is why I recommend the fan I do in the ventilation article that you linked to.

Good luck!

Kal