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Old 05-26-2011, 03:24 PM   #1
Jan 2010
Posts: 272
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So, I live in AZ, and it is warming up. I keep the ambient temperature of my house 85 during the day, and 80 at night (big house, and I am cheap). This is not good for beer brewing, and using the ol "tub with ice + fermenter" method, still doesn't maintain my beer at a constant temperature, even with switching out frozen water bottles twice a day.

I want to build a temperature controlled fermentation chamber/box and implement a window A/C unit. I plan to modify the thermometer on the ac unit so it will be attached to the fermenter.

Has anyone ever built something like this before? I have not yet drawn up a schematic to make this happen, but I know with a setup like this I will need some kind of one way door that will let warmer air escape from the chamber while the A/C unit is running. I do intend to make it close to airtight, and since I have never built anything like this, and I also need ideas for what kind of material I should build this out of.

I am also considering getting a fridge or a freezer and adding a temperature controller to it, but I have to weight the cost of it. I would like to build a chamber with and A/C unit, or buy a fridge with a temp controller for around $150.

I would not buy the fridge, or the A/C unit new if I was to go either way, I would hunt for a good deal on Craigslist. The nice thing about having a fermentation chamber, and building it myself, is that I can incorporate it into a closet in my home where it will be hidden from view (to keep SWMBO happy). She wouldn't be too thrilled with my Keezer AND another fridge...

Thoughts? Idea's? Input is greatly appreciated.

Thank you!

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Old 05-26-2011, 03:52 PM   #2
3 Dog Brew
3 Dog Brew's Avatar
Oct 2006
Houston, TX
Posts: 291
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My Fermentation Chamber

I tried to build this with the coil from a mini-fridge, but wound up with a small window a/c unit as you have suggested. I used R13 fiberglass insulation, but if money had been more readily available, would have used the R22 spray in foam insulation. It holds a nice temperature for ales at 62-68F but much below that and it will freeze up. Another thing is that I used a couple of squirrel cage fans to move the air from the bottom to the top and wound up needing to redirect one of the blower outlets to blow directly on the A/C coils to prevent them from freezing up.

Let me know if you have more questions. I love mine, it just needs more insulation.
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Old 05-26-2011, 06:16 PM   #3
Apr 2011
San Diego, California
Posts: 2

I am actually in the process of building my own AC unit cooled kegerator/keezer/fermentation chamber. I have found that if you can over-ride the temperature control on the AC unit (electrically with modern ones or bypassing the old mechanical temperature regulator), then you can get them to cool down below freezing.

You mentioned that you had an idea for the temperature control so I won't go into that. As far as air flow goes, it is a fully enclosed system. The cooling side of the AC unit pulls air in across the radiator and blows it out through a duct just above it so you don't need to deal with venting or drawing in air. All you need to do is mount it like you would in your house, but instead of sticking in a window into a room, you are sticking it into a small box filled with beer in various stages of progress.

On the construction side, there are a number of ways to go about it. The simplest is to use foam insulation panels (white, pink, or blue) to build the box and provide insulation. The foam isn't really strong enough to allow for multiple levels, but for a single level it should work. Also, if it isn't providing enough insulation, you can always double layer it.

I am finishing up the temperature controller for mine now and should have a blog post up on it in the next couple weeks, but to give you an idea, Here is a link to my teaser post.

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Old 05-26-2011, 10:48 PM   #4
itsme6582's Avatar
Nov 2009
Posts: 883
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If you're handy, you can get pretty creative with these designs
Son of a Fermentation Chiller (pdf)
Mother of a Fermentation Chiller

and the budget buster...
Ultimate Conical

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Old 05-26-2011, 11:48 PM   #5
Oct 2010
Atlanta, Georgia
Posts: 554
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This was mine...

Key word WAS. I recently moved to a chest freezer and haven't looked back. When the AC unit kicked on it sounded like an airplane in my garage. It wasn't bad but the chest freezer is about 1000X better and efficient.
Denny Conn - “The best beer possible with the least effort possible while having the most fun possible!”

Me - "Gun Control Means Using Both Hands."

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Old 05-27-2011, 12:03 AM   #6
Jul 2009
Posts: 182
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I am thinking AC unit is not as efficient. I have a small fridge that holds a carboy or bucket no problem. It doesn't run very much and I never hear it. It wouldn't take much to take the door off and add a box to the front to ferment in.

I am cheap like you and a window unit AC is not efficient. That is why I went with the fridge instead.
Olde Brick House Brewery....I live in a brick house built in 1782.

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Old 05-27-2011, 12:13 AM   #7
BioBeing's Avatar
Jan 2009
Memphis, TN
Posts: 1,520
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I just modded my chamber from mini-fridge to window A/C. The fridge just couldn't keep the box (big enough for 3 carboys) cold enough even for ale. It's in my garage, which has been over 90 already this summer. Right now, it's holding 40 nicely.

My box is basically 2 layers of 2 inch pink foam insulation.

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Old 05-27-2011, 12:18 AM   #8
Feb 2011
North Central, Ohio
Posts: 509
Liked 31 Times on 22 Posts

Here is a neat controller for using a small air conditioner, but they're expensive. There may be some way to do it with a micro-controller & some programming - maybe some people in this group have tried something similar? http://www.storeitcold.com/

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Old 05-27-2011, 07:16 AM   #9
Apr 2011
San Diego, California
Posts: 2

I'm actually doing a super simple controller for my first version. I am using an MSP430G2231 with a built in temp sensor, a basic relay driver chip, and a 12v relay to bypass my AC unit's mechanical relay. All told it'll cost <$10, programmer included (soldering iron and EE degree separate).

My next version will use a separate thermistor probe and might have a simple display and input to change the temperature. The final one will be hooked up to a wireless module that will allow it to communicate with my home server to log the temperature data and allow me to monitor and set it from my Android phone anywhere I have a data connection. (I may be just a little ambitious...)

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Old 09-20-2011, 05:14 AM   #10
kickrjason's Avatar
Jun 2011
Phoenix, AZ
Posts: 285
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Originally Posted by kbrtny View Post
The final one will be hooked up to a wireless module that will allow it to communicate with my home server to log the temperature data and allow me to monitor and set it from my Android phone anywhere I have a data connection. (I may be just a little ambitious...)
Any progress on your ambitious final plan?

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