Keeping Homebrew Chill

Brewing in regions of the world that have extreme temperatures (like Texas) can provide some unique challenges to the home brewer. When the heat regularly gets up past 80 degrees Fahrenheit, those temperatures can seriously affect the taste and quality of any beer you are brewing. Overheated fermentation can cause a host of problems including yeast problems, semi-toxic offshoots of alcohol in the brew, and a big taste difference.

Keeping Homebrew Chill
Room temperature fermentation and conditioning of your homebrew is usually the easiest and most convenient method, but not always the best for your brew.

This is why it is advised to ferment your beer in a refrigerator or in your kegerator's cooling chamber if the temperature gets above 72 degrees where you live. Ideally, most beers should be fermented even colder to ensure a proper and thorough fermentation. By using temperature controllers in your kegerator, you can keep your fermentations at the 68-73 degrees Fahrenheit that is most advantageous to the fermentation process. Here I will go over some ideas for using thermometers, temperature controllers, and thermowells that can help with this aspect of home brewing.

When fermenting, I always like to have the stick on thermometer as a quick reference for each carboy or steel fermentation vessel in the cooling chamber. This is a good back up system for verifying the temperature. As a primary system of temperature monitoring, the digital air thermometer is what most people use, but temperature controllers can also be hooked up to a digital thermometer mounted in a thermowell. [Homebrew Temperature Controllers]

A thermowell is a modification that can be made fairly easily to any non glass fermentation vessel. The idea is that the thermowell reaches inside the fermenting wort to more accurately measure the temperature of the liquid, as opposed to a conventional air thermometer, which measures the ambient air temperature inside the cooling chamber.

MPT Thermowell
MPT Thermowell

Most refrigeration devices rely upon the conventional air thermometer's measurement of the temperature variation in the cooling chamber - meaning the air temperature is being measured, not the temperature of the fermenting wort. For the specific application of the cooling chamber for fermenting or serving beer, the use of a thermometer mounted inside a thermowell can be more accurate.

The variation in the air temperature inside the cooling chamber can be great, especially if the door to the cooling chamber is often opened and closed. I have met more than one home brewer who uses their refrigerator-conversion kegerator as a store house for special vintages of their bottled home brew.

Thermowells that are specifically designed for home brew applications are available through or can be made in the D.I.Y. fashion. One home brewer's set up that I saw used a length of crimped copper tubing and some common pressure fittings from the plumbing department to produce a thermowell modification for a mash tun. The whole mod cost less than $15, and was very quick for him to install. [Thermowells]

When it comes to mounting a thermowell in a glass carboy, you will need some custom hardware. The good news is that double-holed carboy stoppers are available, and you can either buy a stainless steel probe for around $20 or make one out of ¼" copper tubing with a crimped end for cheap.

Double Hole Carboy Thermowell

If you decide to use a top mounted thermowell to monitor your fermentation, or to control the temperature of your cooling unit, you will need the right thermometer to plug into it. Thermometers come in either analog or digital format these days. Analog thermometers are more reliable, but it is difficult to find one that can interface with an automatic temperature controller to maintain the ideal temperature for your home brew. Since various types of home brew are best served at slightly differing temperatures, having a set up with a temperature controller with a digital thermometer accurate to at least one degree Fahrenheit of difference is important.

As far as analog or mechanical temperature controllers go, you have the old stand-by of the Johnson Controls gas capillary tube on/off controller, first introduced in 1990. This controller is uses the mechanical action of the gas in its closed system to activate an on or off power adapter for the cooling unit's power plug. This unit will fit inside a thermowell, but you may have to do some drilling to get the capillary tube or power cord inside your cooling chamber. His unit does not have a temperature read out, so you will need an additional thermometer to gauge the setting properly. Once the controller's setting is dialed in, it should work just fine. On fridges, this unit can keep the temperature in the range of 37 degrees Fahrenheit to 80 degrees Fahrenheit, and if used with freezers, the range improves to 20 degrees Fahrenheit in the low side.

For digital temperature controllers, Johnson Controls also offers a digital controller that costs a little more but has some nice features - like a temperature read out, for one. The unit is called Johnson Digital Temperature Controller Wired FE611. This unit is nice because it has an anti-short cycle feature which will save some wear and tear on your refrigeration motor. This feature stops the wear and tear of turning to motor on and off in rapid succession by applying a timed delay to the action of the solenoid that turns the power on and off. The price is very reasonable, only about $20 more than the analog controller, and with a much more utilitarian feature set.

Here is one last note for the home brewers who operate in colder regions. If you are brewing on a smaller scale and in a colder climate, you can still ferment at the right temperature by using The Ferm Wrap Heater. This unit is composed of a heating mesh that fits snugly around your glass carboy and heats is just enough to keep the fermentation at the correct temperature. If you do live in such chill climates, the option for heating an individual carboy can free up some space in the living room and send the brew to the garage.

Christian Lavender Christian Lavender is a homebrewer in Austin, TX and founder of and

Related Home Brewing Articles :
Build a Home Brewing Kegerator Fermentation Chamber -- The fermentation chamber will let you keep your beer's fermentation temperatures stable.
Build an Insulated Keg Fermenter -- Use a rubber insulated keg for greater temperature stability.
Cold Storage Conditioning in a Kegerator -- Cold conditioning your homebrew in a kegerator can be a useful technique for clearing and building additional body in your brews.