Knights of the Mashing Fork
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  • By: Bryan Peretto

The Cold Room

Even at the beginning of my homebrew career, I envisioned my basement being an Irish pub. As it was, the basement was one big concrete room with some mechanicals, washer and dryer, and a whole lot of crap in storage.

I knew how important temperature was to both fermenting, storing, and serving beer and its ingredients. I decided that since I was building walls and rooms to partition the basement, I might as well build a cold room for my beer.

Iíve seen one or two articles on the web where people have turned a small corner of their basement into a walk-in fridge with the use of an air conditioning unit. Iím going to assume you, or someone you know, is familiar with basic construction and electrical. If not, this might not be a project you should attempt, and I surely wonít be held responsible for your stupidity.


One article claimed that you should use the LOWEST BTU (3k) air conditioner for your cold room because a larger unit will cycle the compressor on and off too quickly, leading to premature failure of the unit. They claimed to get 15 degrees below ambient with the AC.

Another article used a high BTU (20+k) unit and they claimed to have almost frozen their beer. One of my concerns was cost. Not just for the unit itself, but operating cost in electricity.

I eventually purchased a 6k BTU unit with manual controls. I was afraid that I wouldnít be able to rewire a digital system properly.

The Room

Other than the AC advice, I pretty much winged everything else. I built a roughly 4x8 foot room in my basement where one of the walls was the outer basement wall, itself. My ambient basement temperature can be anywhere from 55 to 75 degrees during the year.

The room was made with your standard 2x4 inch studs. The studs and rafters were insulated with your typical fiberglass insulation (paper facing out).

The inside of the cold room was finished with paneled insulation that has a reflective foil face. I taped the seams with a foil tape.

The inside of the room contained a built in shelf on one side. It was built into the structure itself and has held a few hundred pounds of grain and beer at any time. Obviously, you need to frame an opening for the AC unit as well.

The door, because Iím cheap, was made of a piece of plywood with an attached piece of expanded polystyrene for insulation.

Readying the AC

Getting the cover off of the AC unit was probably the hardest part. After that was completed, I located the temperature module- itís the thing with the probe coming out of it thatís also attached to the temperature knob.

Luckily, the wires all had connectors on the end. I simply pulled the wire going from the power to the temp controller and the wire from the temp controller to the on/off switch. Taking out the temp controller, I directly wired the AC to go from the power to the switch. That means the compressor will always be running when the AC is on, no matter what temperature the room is at.

So, how do you regulate the temperature? CíMon- youíre a homebrewer! You use the typical temperature controller as with any chest freezer.

But ACs drip condensed water. Yeah, youíre correct there. Fortunately for me, I can just run a hose from the AC to a dry well in my basement. Some of you are lucky enough to have utility sinks in your basement. Thatíd work, too. In a worse-case scenario, youíll have to use a bucket and remember to empty it every few days depending on the season.

Using it

Why would you choose a cold room over a chest freezer? Space is the biggest reason. I keep 8 kegs on tap at a time (I have room to put one more on). Theoretically, I could probably put in 14 taps on the front and at least 6 along the side if I wanted, with enough room in the actual cold room for the kegs. I may be a passionate brewer and drinker, but even thatís excessive for my needs.

I keep the room about 50 to 55 degrees throughout the year. Not only is this a great serving temperature, but I also ferment my ales and lagers at this temperature! Yes, I said I ferment my ales at 50 to 55 degrees- and they love it.

In the dead of summer if people open the door too much, it can cause the AC to run so long that ice begins to form on the coils. When that happens, it interrupts the flow of air and the room doesnít get cold and the AC continues to run and run and run.

The first solution would be to mount your temp probe to the air intake of your AC unit. If it freezes over, the controller will power off the AC unit. Since I mounted my temp probe on the other side of the room, I havenít had a chance to move it. Instead, I used a heavy duty appliance timer with indefinite 15 minute on/off settings. I set it to turn on and off every 15 minutes so that the AC will never continuously run even if the coils do freeze over. Itís added insurance that everyone should install.

Ok, Bryan, how much does this all cost? Well, I donít have one of those wattage meters, but I can tell you that in the first month of using my cold room, my electric bill was $20 LESS than the previous month. So it obviously didnít have any significant effect on my utility bill. As far as materials, the AC unit was about $100, and the temp controller is about $50. I bought my materials along with more for the whole basement project, so I canít give you a figure. Iíd guestimate that it was around $300 for wood, plywood, insulation, and misc supplies. Try getting a 4x8í chest freezer for $450.

What would I do differently? If I had the money, a real door would have been nice. More insulation is always better. I would have gone with a slightly bigger AC unit. Maybe 9-12k BTU.

I would have considered lighting a bit harder. Right now I use two bright motion-detecting night lights. With the reflective room, they do a pretty good job. Itís not like I sit in my cold room all day, anyways.

Maybe, just maybe, I would have opted for a 15 cu foot chest freezer. But I honestly think I wouldnít be able to do all the things I am now with that setup. In addition to the 8 kegs on tap, I also store a few cases of bottled beer (homebrew and commercial) as well as full kegs in waiting. I usually have at least 2 fermenters in there, sometimes up to 6. Plus I stack more than a few bags of grain in there where itís cool, dry, and dark.

Lastly, itís just cool (no pun intended) to have a cold room.

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Printed from: on Oct 22, 2016
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