Small Batch Brü

Recipes, techniques and tasting notes

fermentation fridge

Fermentation Chamber Build: Getting Serious About Temperature Control

If you’ve read How to Brew by John Palmer, or if you’ve ever listened to the man speak, then you know that fermentation temperature control falls second (sanitation being number one) on his list of priorities when it comes to brewing great beer.

To keep things simple; fermentation temperature control keeps your yeast happy. And when they’re happy, they excrete a lot less compounds into your beer that will lead to off flavors. After all, brewers make wort – yeast make beer.

So after almost two years of homebrewing I’ve decided to step up my fermentation temperature control game. I decided to convert a mini fridge into a fermentation chamber. Up until now I’ve been using the Cool Brewing fermentation bag. I’ve been able to keep my temperatures fairly steady for most of the ales that I have brewed. My biggest gripe with this method of temp control is that I need to change out the frozen water bottles every 12 hours or so. I’m actually not home a whole lot so that job usually falls on my better half, Liz. I don’t like burdening her with babysitting my beer, so I went out and bought the fridge. The other plus is that I can now brew lagers!

The Fridge

I went with the Galanz 4.3 cubic foot mini fridge from After some research and measuring of my space, I found that this was really the smallest and biggest fridge I could use. Smallest meaning anything smaller than 4.3 cubic feet really won’t work well as a chamber, and biggest meaning I only had 19 inches of width to work with.

If you decide to go with a mini fridge as your fermentation chamber, then you are more than likely going to have to remove all of the shelving from the door. Newer fridge models’ shelves are injected with foam for insulation. I would recommend cutting away all of the foam and plastic – JUST BE CAREFUL AND LEAVE THE PLASTIC THAT HOLDS THE GASKET IN PLACE. Remove the gasket and cut the plastic and foam away that is keeping the door from closing. I was able to cut most of the foam away – and I even cut a little extra out to leave a little more room for where the carboy sticks out of the fridge.

Cut the foam out of the door.
The bottom of the carboy sticks out a little - cut foam to fit.

Materials and Insulation

To replace the insulation I removed, I used Reflectix and aluminum foil tape to cover the foam. This also cleans up the look a little bit. I got both of these materials at Lowes for about $10.

Paint, reflectix and aluminum tape
Cover the inside of the door with reflectix and aluminum tape

Then I took the door outside and sprayed it with a few coats of black chalkboard paint. DON’T USE CHALK MARKERS WITH CHALKBOARD PAINT. I THINK REGULAR CHALK WORKS A LOT BETTER.

While the paint was drying, I drilled a 1/4 inch hole in the side of the fridge and inserted a rubber grommet in the inside and the outside walls. I then ran the temperature probe through the wall and into the fridge. The grommet seals up any leaks and also just looks nice.

Painted black with chalk board paint

I decided to leave the shelf as-is. I’ve seen other projects where people bend the shelf down. I just didn’t want to break the coolant hose. If you are going to bend the shelf – USE EXTREME CAUTION. The coolant is under pressure and you could injure yourself. And probably ruin your fridge.

Hole for the grommet and temp cable

When fermenting, I just have the fridge thermostat set to the highest setting and use my temperature controller to turn the compressor on and off. If you have any questions about building your own fermentation chamber, feel free to email me or leave a comment here!

Thanks for reading.