Fermentation Chamber Build

As a home brewer there is only one thing I can’t control. One is the water temperature from the city. The temperature, especially during the summer doesn’t drop past 75-80 degrees in the summer.  In the winter, its about 65-70 degrees. However, if you live in the south you know that it doesn’t stay cold for long. A couple of days of freezing temperatures followed by 50-60 degree weather doesn’t help keep fermentation consistent.

Recently, I did two brews, one is the Chocolate Porter Brown Ale Fail and the other was an IPA called Blue Lagoon IPA that has Polaris and Horizon hops in it. Because I can’t control my water temperature my beer was consistently too warm when I pitch my yeast. I was almost killing the yeast before it ever had a chance to make alcohol. The other issue was that I wasn’t hydrating my dry yeast (I use US-05 a lot because of cost). Hydrating the yeast allows it to start working and it allows it to have a great head start at fermentation the wort.

I had to do something. The first thing is I’ll get wet yeast, do a yeast starter and wash the yeast allowing me to reuse it without having to buy more. The other thing I did was build a fermentation chamber to control temperatures. Let me show you what I did.

Items needed to Build a Chamber

To build a chamber like I did, I first had to get a mini fridge. I used a 3.1 cubic inch mini fridge that I found on OfferUp for $10. I grabbed some CuClean and my youngest son and cleaned the heck out of it. As you can see in the picture below it was pretty filthy. It had lots of dirt, mildew and more that had to go.

I took off the door because, as you will see later, it wasn’t going to stay in its present location. Sprayed it down with water, CuClean and got a scrub brush and cleaned it really well.

Next, Owen and I made one of many trips to Lowe’s to get supplies. On this first trip we got

  • (3) 2×4’s
  • (4) 2×3’s
  • Box of 2 1/2 inch screws
  • (2) tubes of Liquid Nails (we returned one later)
  • (2) 4 foot by 8 foot Styrofoam panels (we returned one later)
The Build

We started off by make a a frame out of the 2×4’s

The measurements are 48″ long by 18 3/4 inches wide. As you can see the fridge sits at one end perfectly. The frame is just a bit wider by about 1/2 an inch to allow for proper circulation.

Next I built a frame around the fridge (as seen below)

As a wood worker one of my favorite tools I have is a Kreg Pocket hole jig. No more toe nailing screw in and splitting the wood. Simply adjust the jig, drill and done. Its amazing. I also had a scrap piece of 3/8″ plywood from some cornhole boards I made last year so I put that on the bottom for extra stability. One 6.5 gallon carboy filled with beer can weigh upwards of 40-50lbs. I wasn’t just going to just put the Styrofoam on the bottom. It would crush it. You can also see where the door will be. Its not mounted in this picture, it is only there temporarily. Also at this stage of the build I added four wheels, two that lock and two that don’t for easy transport.

The Sytrofoam

Now that the frame is done I started adding the styrofoam on the the sides. I put a nice amount of Liquid Nails all around the wooden frame, and as you can see in the picture I grabbed some weights and clamps to help keep it sealed. On the inside of the, I took some white caulk and caulked the heck out of the inside around the styrofoam to give it a great seal.

After the glue dried over night, I took some Reflextic Tape and taped up all the edges on the outside to reinforce the seal.

**Note** at this point I should have put in my fan and temperature controller but I didn’t have them yet. Excitedly I continued. But I should have waited.

Here you can see the way that I put the styrofoam on. Starting with the end piece and then the sides and bottom, I added liquid nails, caulk and tape. I overkilled it probably on the tape, caulk and liquid nails. But I was going to take any chances.

First Test

After completing the box, insulation and taping it enough, I put the door on and did a four hour test. In 4 hours the inside of the box went from 77 degrees to 70 degrees. So far so good. I turned off the fridge and went to bed (day 4).

Hanging the door

Putting the door on the chamber proved to be more difficult then I ever imagined. As you can see in lots of the pictures there is a plastic shell around the inside of the door. At first the door seated well in the opening, until I got the hinges. The first set of hinges were too big and had to return to Lowes to get thinner  hinges. When I returned with the correct hinges, I noticed that there wasn’t enough space to put them on the frame.

Frustratedly, I ripped off the gasket and the plastic shell and was finally able to get the hinges to fit. However, drilling the screws in the frame I quickly noticed that there wasn’t much that the screws were being held by. The thin sheet metal on the frame of the door wasn’t going to be enough to hold the door on. I had just enough Liquid Nails left and placed some in the holes for the screws for reinforcement. So far so good.

At least thats what I thought. After getting the hinges on, I had a big (2×4) gap at the bottom of the door where the plastic shell covered before. Scrounging around my shop, I found a 2×4, cut it to length and placed in where it needed to be. “Yes” I thought, I’m done. Nope. I then discovered that the leftover foam inside the door needed to be flatter around the edges so make a better seal. Slicing up and making a mess I got the door edges flatter. Then I discovered it. The door is warped, just enough to frustrate me.

Back to Lowes

I went back to Lowes to get a hinge lock to be able to lock the door on the chamber. But as I just mentioned, the door is warped. Looking around the shop I found a big roll of weatherstripping and started working on making the door sealed tight. Not sure what to do, I took a step back.

Gathering my whits about me I figured it out. I had my hinges too shallow. Let me explain

The door wasn’t closing tight enough for my liking and just didn’t sit well with me. Then it clicked. If you look at the picture on the right (above) I added a 1/2 slat for the hinges to attach to. Hoping that would work I looked straight down and could see the floor. There was a gap between the door and the frame. Shoot!


I had a little bit of the styrofoam left over and some Elmers Craft Bond and bam. I cut 1 1/2 inch strips of styrofoam and glued them around the inside frame of the door. Once I had that completed, Owen and I added the door back.


Finally getting the door hung I added the electronics and the fan. I cut a small slit in the top of the styrofoam and inserted the temperature controller and the fan. I mounted the fan on top of the frame (as seen below) to add some circulation inside the chamber. Once I had the fan mounted I turned on the temperature controller and set it to the proper temperatures.

Final Thoughts

I’m testing the chamber now to see how it is going to work, but I think it will be fine. I think I’m about $120 into the build give or take. It was a fairly easy build considering the necessity of it.

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