Build Your Own Glycol Fermenter

Professional brewers control the temperatures of each of their individual fermentation vessels. To accomplish this, homebrewers are typically stuck using multiple chest freezers or refrigerators to control fermentation temperatures. I wanted to have temperature control over each of my fermenters like the pros, to store them within the confined space of my garage, and also still use my garage for its intended use . . . to park cars. So with a little research, welding, design and patience I built this temperature controlled fermenter.

This project does not require a lot of space to build or store. I built it in my garage and store it along one side next to my brewing system. All of the materials can be easily obtained and the whole thing can be built for about $2,000. You can ferment a lager in one vessel and an ale in the other; raise the temperature for a diacetyl rest and even crash cool to near freezing before kegging to help clear your beer.

I am a makeshift welder, and I’ve always wanted to learn how to weld stainless and aluminum. My solution was to take a TIG (tungsten and inert gas) welding course at the local vocational school. This is where I actually came up with the idea of a jacketing system for my Sabco fermenters. You may choose to do this as well or, armed with a six-pack of your favorite homebrew, you can find an experienced welder that will weld this part of the project for you. With a good understanding of how the chiller is going to work and look, this project will come together in a snap.

I used a 5000 BTU window air conditioner and a standard size ice chest for the chiller unit. The air conditioner’s evaporator coil is immersed in a glycol bath to cool the glycol. A small fountain pump is used to constantly circulate the glycol solution inside the cooler. Two slightly larger fountain pumps are used to circulate glycol through copper tubing that is wrapped around each fermenter underneath an insulated jacket. These larger pumps are switched on and off by a temperature switch that is monitoring the temperature inside each fermenter.

The Ultimate Chiller provides great temperature control. I set the glycol temperature to 30 °F (-1 °C) during primary fermentation, which allows adequate cooling so I can set the fermentation vessels at either lager or ale temperatures. After primary fermentation is complete you can raise the temperature for a diacetyl rest then lower to near freezing to help settle the yeast and clarify the beer before racking.