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Old 09-24-2009, 08:30 PM   #1
Oct 2007
Posts: 66

I'm thinking about building a fermentation chamber and using either an A/C window unit or a mini-fridge using the standard insulation style of build.

Those of you with experience with this, which of these do you think would be better, more efficient?

I would be interested in the Pros and Cons of both of these.

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Old 09-24-2009, 08:38 PM   #2
Apr 2009
Somewhere in the middle of Nebraska
Posts: 873
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I went the AC route. Chamber is 3'W 4'L 6'T OD. Found a Haer 5250 AC unit at Wal-Mart on clearance. Has to be the manual control type, not remote. Moved the temp sensor from the front of the unit to the back to keep it from shutting off prematurely. Regulate it with a Ranco control. Used 2 layers of 3/4" insulated sheathing. Gets to 32F in just a few minutes.
If Homebrew & BBQ aren't the answer, then you're askin' the wrong questions... Cheers!!!

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Old 09-24-2009, 08:42 PM   #3
Sep 2009
Posts: 16
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IMHO - It depends on the beers you brew most, and volume that you are cooling.
Note I have no experience with either of these but, I would think that if you are lagering a mini fridge is going to stand up to the cooling demands much better as long as you are not trying to keep a large volume at 48 degrees. Where as window AC unit will handle the Ale temps better. In addition a window A/C moves a fair amount of air without adding any other fans, so may be easier to cool larger volumes.
The Belly

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Old 09-24-2009, 08:58 PM   #4
lamarguy's Avatar
Aug 2008
Austin, TX
Posts: 1,653
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Have you considered a frost-free upright freezer + Love controller? You can find upright freezers on Craigslist and scratch-dent models at Lowes/Home Depot pretty easily.

Pros -
  1. Already designed to be an energy efficient cold box.
  2. Frost free design (unlike an A/C unit or mini fridge).
  3. Sheet metal is most likely sturdier and lighter than a homemade box.

Cons -
  1. May cost slightly more than an A/C unit build (depends on source).

I've purchased two brand new scratch-dent upright freezers over the last couple of years, one for $300 (13.7 cu ft) and $350 (20 cu ft). They make excellent fermentation enclosures.
Doggfather Brewery

Planned: Lambic, American IPA
Fermenting: 6 gals of 1.090 stout (Belgian) & 6 gals of 1.090 stout (English)
Tapped: Berliner Weisse, Black English IPA, German Pils, & Live Oak Primus

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Old 09-24-2009, 09:01 PM   #5
Feb 2009
Albuquerque, NM
Posts: 320
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The ac generally has realllllly high btu/$ number and is meant to cool large areas. I bypassed the thermostat on the unit and use an external controller. I haven't had any issues maintaining 45F with my 5000btu window ac.

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Old 09-24-2009, 09:06 PM   #6
Aug 2008
Portland OR
Posts: 5,387
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+ Haier 5200 btu from Target on sale about $75, to maintain a 65F ferment the thing barely kicks on. Added $20 heater for the winter months coming up. About the same size fermentation area as poster#2. Also moved the thermo to the outside of the cabinet, took about 5 minutes to get that done.

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Old 09-24-2009, 09:06 PM   #7
Apr 2009
Longview, TX
Posts: 529
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Whatever you find cheap gets my vote. That even includes freezers if you can find one (I can't since all the hunters around here snap 'em up).

Cheap is why I went with a dehumidifier
Primary:A simple Bock, Vienna

Bottled: Centennial Blonde, Mostly Dead Guy Ale, Pale Rye Ale

On Deck: waiting...

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Old 09-24-2009, 09:06 PM   #8
Feb 2009
Albuquerque, NM
Posts: 320
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Added my build thread to my sig if you're interested...

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Old 09-24-2009, 09:29 PM   #9
Cpt_Kirks's Avatar
Sep 2008
Lakeland TN
Posts: 3,723
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I used a 4.5cf Haier fridge and some 2" pink foam board. It maintains a steady 62*F or 49*F with the fridge almost never kicking on...and that was in the hot part of the summer.

I don't even have the lid attached, it just sits on top. The box is big enough for two six gallon Better bottles and a couple of cornies.

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Old 09-24-2009, 09:41 PM   #10
ThreeTaps's Avatar
Aug 2009
Pacific Beach, CA
Posts: 520
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This brings up a really good point. I have an A/C unit that I was planning on using for my garage closet, however it's a digital one that has a remote with it. You don't need the remote to operate the unit, but it doesn't have a dial that you can set to an "on" position so it turns on whenever power is sent to it.

This basically makes my current A/C unit non functional for my fermentation chamber, eh?

...Unless of course I can take it apart and find the current sensor, then splice in about 5 feet of extra wiring to extend it to the middle of the cabinet.
Justin H.
Brew Blog: Three Taps Brewing
Primary: Centennial Blonde Ale, Deception Cream Stout Secondary: Empty.
Bottle Conditioning / Drinking: Pumpkin Spice Ale, Cherry Wheat Ale, Bee Cave IPA, EdWort's Apfelwein.
R.I.P.: Bee Cave Haus Pale Ale, Oatmeal Stout, Pecan Scottish Ale, Nut Brown Ale, Blonde Ale.

Brewing Since August 17, 2009
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Originally Posted by shortyjacobs
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