I have a passion, a "sickness", my wife calls it. I love beer - and I love to make it. I have been homebrewing beer for about 11 years - ever since my friend, Ross, showed me how to do it on his stove back in South Carolina. It is the perfect hobby.


There is fabrication, science, cooking, and the best part, consumption of the final product! I started brewing on the Connecticut coast, where the weather is very mild throughout the year. Sure, it gets cold in the winter or hot in the summer, but the extremes are not that bad for that long. Then I moved to the Southwest...

The Problem with Summertime

In Arizona we are blessed with 300+ days of sunshine. We are also "blessed" with 90F+ degree tap water in the summer and 110F+ degrees outside. In order to not go broke, my house has setback thermostats that keep the temp at 78 while we are away during the day, and 75 when we are there. The wet t-shirt trick works like a charm - except in the summer. Because it is so dry I can usually get about 10 degrees off of the ambient. Still, I much prefer to use my chest freezer with a temp control to keep fermentation consistent. The "problem" is it is usually filled with full kegs at lagering or serving temps.

Using the Freezer I Have Instead of Buying Another One

I had to have a better plan for fermentation. I looked at designs such as the Son of a Fermentation Chiller, and the 38DD version, but I didn't feel like messing with ice jugs daily. A second chest freezer was out of the question - I just don't have that kind of space. I have also seen people put partitions in their freezer or put a Fermwrap on the carboy inside the freezer. The thought of having the freezer and the heater fight to the death while I line the pockets of the electric company gave me chills (pun intended). Then it hit me. The chest freezer is so efficient because the cold air sinks. There is not much loss when you open the top. I needed to design something that took advantage of the laws of thermodynamics - cool air sinks, and warmer air rises. Thus was born the Mother...

The Design

Since this thing was going to be permanent I had to figure out a way to get to the bottom kegs. I designed the floor of the unit to have two trapdoors and a removable center support. Access to the ferm chamber is from the front. The unit has a dedicated temp control to keep the freezer at serving temps and another one to control the fans for the fermentation. The top unit has two 120mm fans to circulate the cold air. To improve cooling efficiency, I added two 4" X 24" ABS pipes as intake and exhaust tubes. The cold air intake goes down into the freezer. I cut it so that it stops 1" short of the compressor shelf. The hot air exhaust sticks up inside the fermentation chamber and returns the warmest air back down into the freezer.

Construction Details

The ports were constructed by first adding a flange to the ends of the two pipes. I glued a coupler to the pipe then cut it almost entirely off on a table saw leaving a lip to fit a routed groove.

The entire box is constructed of birch plywood that I found at the local Home Depot. What would be the collar on a normal chest freezer mod is made out of 2 X 4s. Each corner is strengthened with 2 X 2s. Insulation is two layers of 3/4" rigid foam insulation - "extruded" polystyrene, not "expanded" (a.k.a. coffee cups). The top and middle is wrapped with some 1 X 4" poplar stained with red oak stain. At some point I intend to finish the wood with some satin polyurethane. I have room for 6 taps on the left hand side spaced 3" on center. An 18" drip tray will also be added later.

The Mother Put to Use

My 14.8 CF freezer can hold six kegs comfortably (eight if I squeeze them in "8o8o8" configuration). The Mother will hold (4) 6.5 carboys comfortably up top. As for the gas plumbing - the initial plan is to run with two secondary regulators (one for "normal" beers, and one for belgians and hefe's). One regulator will be hooked up to a 4 way manifold and the other a 2 way manifold. I also intend to have a mechanism for counter pressure filling outside the unit, or purging kegs prior to transfer.

As of this writing I still have not fermented in there as I have been called away on business and leisure travel (Ed: "called away" on leisure travel. How nice, Mylo!). However, I did do a test of the cooling capacity. It is entirely possible to ferment lagers up top. However, I'll probably refrain from lagers at least until the temps return to the 70's in my Arizona garage.

Brew Strong!

MyloFiore is an avid homebrewer and lives in Scottsdale, AZ with his ever-enduring wife, Nancy, pre-teen son & daughter and Yorkie, Winston. He can often be found raising hell on the Brewing Network's forum. If he were a beer he would be a Saison.