Temperature Controllers

One of the most important processes to be controlled in your homebrewery is the temperature of your wort and beer, be it hot or cold. If you want to have a better chance at brewing success, as well as more automation, consider investing in temperature controllers to help keep fermentation and mash temperatures more consistent.

What are they?

Temperature controllers are electronic devices — essentially switches — that monitor the temperatures of your mash or fermentation and turn heating or cooling equipment off or on based on temperature readings.

On the cold side, a temperature controller installed in a refrigerator or freezer, for example, will override the machine’s internal thermostat and maintain a specific temperature range (known as the differential) by turning off the power to the machine when the temperature goes too low, or back on if it is too warm.

Similarly you can also install a  temperature controller for your hot liquor tank (HLT), which will turn off the heat source when your water heats up to the temperature point you specify. (This setup requires a gas valve pilot light or igniter or a Solid State Relay (SSR) to control the heat source.) If you are all-grain brewing you can also add a temperature controller to monitor your mash temperatures and turn heat sources and pumps on and off depending on your temperature differential. Using temperature controllers on the hot side, however, requires more expert knowledge to install and use safely, so be sure to get assistance from someone who is knowledgeable if you decide to install a temperature controller for anything heat related.

Choosing a controller

Temperature controllers come in a wide variety of models and prices and vary based on what you would like to use it for. For example, a simple model with a digital display and temperature probe for monitoring fermentation temperatures in a refrigerator can be had for around $50 to $100, while more advanced models that can control more than one heat/cold source or pump can cost a few hundred dollars. Temperature controllers are available in both analog and digital models and have a differential between 1 and 4 degrees Fahrenheit (0.5 to 2.2 °C) .

When choosing which controller you need, it pays to do a little research. There are lots of ways to use them, depending on your setup. Get in touch with your local homebrew supplier, or contact the customer service department of your favorite online retailer for advice. And of course ask your fellow homebrewers what works for them.


Be sure when you choose a controller that you are comfortable installing it. Some temperature controllers are as simple to use as plugging an appliance into the controller and then plugging the controller into the wall outlet. Other controllers, however, require some electrical wiring to install. If you are not experienced and comfortable with electrical wiring, stick with using the simpler types of controllers that don’t require wiring, or ask someone with electrical experience to install it for you. Improperly combining electricity and liquids is dangerous and can cause electrocution. Also, for additional safety always plug your temperature controllers into a

GFCI (ground fault circuit interrupter) outlet, which is an outlet that shuts off an electric circuit when it detects that current is flowing along an unintended path, such as water — or a person.

Issue: November 2012