How to control fermentation temperature

Brewing temperature is a key consideration in making great homebrew.

Homebrewing temperature. Why worry?

As we covered in the yeast chapter, your yeast will have a specified temperature range where it will work best.

Below this, your fermentation will stall. The result will be unfermented sugars making their way into the bottle. These will continue to build pressure in this sealed environment until they explode. Not great.

If your beer ferments too warm, the yeast will produce off flavors. Your reputation as a homebrewer will plummet.

Check your yeast packet and work within the recommended range.

Controlling homebrew fermentation temperature

Brew with the season

You are best to brew when the ambient temperature is within your yeast’s working range. This means you don’t have to try to control it.

Depending where you live in the world, you can stockpile your beer during ‘brewing season’ for the coming months.

Brewing heat belts and pads

You can buy a brewing-specific belt that fits around your fermenter and warms your brew. Move it up and down your fermenter to adjust the temperature.

Likewise, heating pads are also available to warm your fermenter.

Use a yeast suited to the ambient temperature

Instead of changing the time of year you brew, change your yeast to suit the time of year. You pick the yeast that suits your ambient temperature.

Here are some reliable dry yeast suggestions for a range of ambient temperatures.

48-58°F (9-14°C)

Most of Fermentis SafLager range (S-23 and W34-70 are popular choices). True lager yeasts work at lower temperatures.

60-72°F (15-22°C)

American ale (eg Fermentis SafAle US-05). Clean and flexible for a wide range of ale beers. Also can make ales that look and taste like lagers.

65-75°F (18-24°C)

Australian ale (eg two packets of Coopers yeast). Fruity notes and performs well at high end of the temperature range. This yeast can reliably work up to 81°F (27°C), but best results are below this.

There are a range of others available but these options will give you a great starting point.

Homebrewing fermenting fridge

You can easily control fermentation temperature with a dedicated brewing fridge.

You can easily control fermentation temperature with a dedicated brewing fridge.

A dedicated fermenting fridge will make homebrewing much more flexible.

This is what I use now and gives me great control over my brewing temperature.

I have an old fridge used only for homebrewing. I run it with an external thermostat to control the brewing temperature.

The thermostat is really easy to set up and use. I can dial in the temperature I want and control with either the fridge’s cooling (summer) or a heat lamp (winter).

The added advantage is that I can clean and sanitize inside the fridge to create a safe brewing environment.

If you have the room and can come by an old fridge easily enough, I strongly recommend this option.

Cooling hacks

There are simple ways to bring wort temperature down to a workable range.

While not as effective or reliable as a dedicated brewing fridge, they can help.

Control fermentation temperature with an old t-shirt.

Control fermentation temperature with an old t-shirt.

T-shirt trick

Cover your fermenter in a clean T-shirt and sit in a shallow water bath. The shirt will soak up the water and the evaporation cools your fermenter.

Ice bottles

Freeze a couple of ice bottles, wrap one in a clean towel and sit on your fermenter at the hottest part of the day.

Pick your spot

If your house is heated or cooled in parts, you can move your fermenter to those spots.

Be warned though not everyone in the house may fully appreciate a fermenter in their bedroom.


cleaning-homebrew-companion-guide

Homebrewing With Kits—The Beginner’s Guide

To help you master homebrewing with kits, I’ve put together a guide based on my experiences over nearly two decades of homebrewing.

This is the information I wish I had when I first started. I hope it helps you make awesome homebrew.

Download your copy today.


Homebrewing basics Series