Fermentation Chamber built with window A/C unit

Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

wulfsburg

Well-Known Member
Joined
Jan 28, 2010
Messages
273
Reaction score
2
Location
Phoenix
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!
 
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.
 
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.
 
This was mine...

DSC00166.jpg


DSC00195.jpg


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.
 
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.
 
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.
 
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/
 
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...)
 
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?
 
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

Do you have instructions on how you did this? I'm going to use an old 3 door Continental Reach-in Fridge that doesn't work. Since I don't have the tools or expertise to fix/replace the compressor an easy route to go may be to just cut a hole and use a window A/C.
 
If you're building a large ferment chamber the A/C is the way to go. I've been running an AC to cool my 15 gal conical for the last few years. I just have a box with 1" EPS foam insulating it. It's not well constructed, nor well sealed, but it will get the chamber down below 10F regardless of ambient conditions. The coil does freeze up when it's humid and I try to do anything below ale temps, but that can be managed with good sealing and control scheme. I've just been too lazy to bother with those things.
 
If you're building a large ferment chamber the A/C is the way to go. I've been running an AC to cool my 15 gal conical for the last few years. I just have a box with 1" EPS foam insulating it. It's not well constructed, nor well sealed, but it will get the chamber down below 10F regardless of ambient conditions. The coil does freeze up when it's humid and I try to do anything below ale temps, but that can be managed with good sealing and control scheme. I've just been too lazy to bother with those things.



i would love to see some pics of your build!!
 
My Fermentation Chamber
...
Let me know if you have more questions. I love mine, it just needs more insulation.

Update: This was been completely dismantled and replaced with a proper upright refrigerator. It started to grow mold because there was no way to ensure that the insulated panels were airtight. The warm humid air lead to condensation inside the panels and before I could see it from the outside, the panels were filled with black mold (of death). See Failed Experiments.
 
So i just finished building my .. :( sort of ugly fermentation and conditioning chamber.

its 28 inches Wide by 25 inches (with a 24 Wide x4 entry way part) by 7 feet high.

I'm not the best with wood working but its .. okay looking. someone posted a MUCH better looking one on here.

anywho AC unit was $35 on craigs and i spent $50 ish on lumber. need to buy 1 last stick of 2x2 so i can rest the shelves . bottom chamber is 30" tall, middle is 40" and the top is like 18"

Fermentor (SS Bucket) will go in the middle chamber,

I bottle, so i figure i would stick Carbing bottles in the top or middle , and move them to the bottom after 2 weeks to let them "age/condition"

so granted there's almost no thermal mass in there right now. my empty SS bucket and 3 cases of empties but my 24 hour thermometer seems to be showing 62-70 as the range. temp is set to 70 .. Maybe the AC unit is too strong? I believe i have it set on economy power saver mode. maybe low would result in better temp resolution. also the AC unit is at the very top and i don't have a top shelf in there yet. and my doors have not been insulated yet either...

sounds like i should try to glue something mold proof on the inside or maybe find a spray / paint that is mold proof / washable ??

so i cut that 2x2 stick that's in the photo , there's now a small beam behind the intersection of the top and middle doors, and a 2nd one behind the intersection of the middle and bottom doors.

i also used magnetic catches so that the doors stay air tight (in theory) was gonna glue insulation to the doors as well but now i'm thinking a spray on might be better.

maybe i'll brew a batch this weekend and try out the cabinet.

IMG_20150715_200607_066.jpg
 
Last edited:
Back
Top