Back to Shopping at NorthernBrewer.com

Mother of a Fermentation Chiller - Airflow

I was wondering if anyone wanted to give feedback on my design for “airflow”… I have three 120mm PC Case Fans, and two 80mm PC Case Fans that I want to use up. So, this is my design:[attachment=0]fermentation_chamber_sketchup.png[/attachment]
The Bottom-Back Fan pulls air from the room. The Top-Side Fans blow warm air out into the room.

Things to consider… Would a closed circuit be a better design? What if only the Intake Fan was on a closed circuit and the Outtake still blew warm air out? Would that create a vacuum? How would that affect it?

Okay, have at it (feedback on the design please). Attack!
ps: The ambient temperature of the room this will be in is about 68 F.

OK, glad to give feedback, but have some questions first. How are you planning to maintain temperature? Is there an air conditioner working on the intake area or are you planning to load it up with ice? If you have an air conditioner, there is no need for any of the fans or separate chamber, so I’m guessing you are using ice. In that case, do you have a temperature controller hooked up to the fan power? If not, you will quickly melt the ice and it is likely that the temperature in the chamber will be too cold until the ice is gone. Assuming that is taken care of, then I see two potential issues with your design:

  1. You are putting heavy buckets or carboys on top of the shelf you build, and you need to make sure it is structurally sound. Styrofoam isn’t enough for that.
  2. There is too much airflow and you are likely to waste a lot of your cooling potential (melt ice too quickly). You really only need one fan to pull the air through to drop the temperature to what you want, and perhaps one more fan to run in the chamber all the time (except when the temperature changing fan is running) to make sure the air in the chamber is a reasonably uniform temperature.

If I was to make a recommendation, I would place the air intake on one of the side chamber on the bottom with no intake fan. There would be vents going from the intake chamber to the middle bottom chamber, then to the last bottom chamber and then finally a single vent from the third chamber to the big chamber where your beer is. A temperature sensor would be hooked to a controller which actuates a single fan to pull air out of the top chamber. When the exhaust fan is not on, you can have a very small fan to circulate air in the main area if you want, but that isn’t really critical, and I’m not sure it would really make any real difference. To minimize losses, you should also hang a flap on the first intake vent to prevent cold air from escaping into the outside, but will freely allow air to flow in when the exhaust fan creates a small pressure difference. If your insulation is decent, you don’t need very big fans for any of this, so 80 or 120mm box fans are plenty big.

If you have the intake air flow through the three chambers in series as I’ve recommended, you can load up ice into each chamber and you’ll get the ice preferentially melting closer to the intake, which could make figuring out a schedule for replacement of ice easier to anticipate.

I understand how airflow (especially from room-temperature) will make the ice melt faster. But, wouldn’t better airflow also cool the top-chamber faster? Therefore, there will ultimately be less airflow overall. So, the rate that the ice melts would maybe be the same.

I suppose since it is such a small space, not that much airflow is needed. I saw a design that is exactly what you are talking about. Where there is a fan in the right chamber, and vents going to each other chamber and a top vent into the vessel chamber.

Yes, I’ll be using ice and all the platforms that you see will be made of wood. The support beams in the “ice chambers” will just be wood, and the rest will be 2 inch foam sheets and wood for support. As far as temperature control, I’m planning on using a “Johnson Digital Temperature Controller” that is outside one of the fermentation vessels using pipe insulation.

It’s nice to see what people are thinking. That’s why I said “Attack!” I’m hoping for a flame-war on this design.

What are your thoughts on a closed circuit Intake and still having Outtake fans?

Any other takers?

What are you expecting your build costs to be? A 7.1 cu chest freezer can do 2 buckets/carboys. (just got one a couple of months back.) Since you’re already committed to a controller, that cost is a wash. I paid $170 new, but used can be found for MUCH cheaper.

Assuming the build goes on, could the ice be at the top? it’s less stooping to replace the ice and convection works in your favor, which would reduce the need for fans.

Regardless of placement, I would worry about melting ice causing condensation, and general damp which leads to mildew. keeping those ice chambers clean is going to be a pain. You could also build around a dorm fridge instead of ice.

BTW, my temp controller runs the freezer for about 5-10 minutes per day. More with an actively fermenting beer producing heat, less with beers in secondary. I think the controller uses more electricity/day than the freezer.

You are wanting to bring fresh (warm) air in, cool it, then expel the warm air?

I can’t say I’ve seen a build like that.

[quote=“Nighthawk”]You are wanting to bring fresh (warm) air in, cool it, then expel the warm air?

I can’t say I’ve seen a build like that.[/quote]
Good point. It would be far more efficient to have NO intakes or exhausts, and simply control a fan that circulates the air through the ice chambers when the main chamber gets too warm.

[quote=“rebuiltcellars”][quote=“Nighthawk”]You are wanting to bring fresh (warm) air in, cool it, then expel the warm air?

I can’t say I’ve seen a build like that.[/quote]
Good point. It would be far more efficient to have NO intakes or exhausts, and simply control a fan that circulates the air through the ice chambers when the main chamber gets too warm.[/quote]

This is why I posted this. Very good point. I haven’t bought anything for my build yet, not even the Thermal Controller. The only thing I have is the 5 fans (from old computers / spare parts). I’m looking for constructive feedback so I don’t make a big mistake in building a pile of junk that doesn’t work.

I think I’ll redesign the entire unit to be a Closed Circuit. I can still use the 5 fans, (I want to get rid of them) I’ll just use them to direct the airflow throughout the Chamber.

Thanks for the input guys!

Here’s the new sketch-up:
[attachment=0]fermentation_chamber_sketchup_closed_circuit.png[/attachment]
The fans direct the airflow over the ice chambers (green ones are 120mm, red ones are 80mm). The 120mm fan on the front-left blows air into the chamber. The 120mm fan on the rear-right is the outtake that blows air back to the beginning of the “snake of ice”.

I think this is a much better design. Thanks for all your help!

Back to Shopping at NorthernBrewer.com