Kit Brewing 101: Brew Good Beer Your Friends Will Drink With You

Tip #2 Keep You Cool.

Does temperature affect fermentation? 

Greatly so – and accordingly home brew kit manufacturers place temperature ranges on their instructions. I would even go as fast as to say that after sanitation, temperature control is the next most important variable you can use to improve the quality of your final product. 

Good temperature control = good beer.

Kit Brewing 101

What is fermentation?

Fermentation is the metabolic process of converting carbohydrates into alcohol. By using yeast as the active ingredient glucose (sugar) is converted into ethanol (alcohol) and produces carbon dioxide as a biproduct (which is released as the bubbles you see in the airlock). 

Why does temperature matter during fermentation?

Yeast the is very sensitive to temperature. In the simplest terms:

To hot – yeast can become stressed leading to excessive levels of diacetyl and other chemicals that cause undesirable flavours.

Too cold – yeast can become lazy and lethargic resulting in your home brew becoming overly sweet from all the unconverted sugars.

Different yeasts are best suited to different purposes – and accordingly have different temperature ranges they are suited to.

What is the best temperature to brew at?

Every brewing kit will give you instructions with a suggested temperature range for brewing. As a guideline – stick within the range and aim for the lower end of the spectrum.

To give you an example for a kit with a recommended temperature range of 18-30 degrees I would want to aim for hold a fermentation temperature of 18-22 degrees Celsius or for a kit with a recommended range of 20-24 degrees Celsius I would want to aim for 20-22. 

What affects the temperature of your fermentation?

The main factors that affect the temperature of your fermentation is the ambient temperature – or the air temperature of the surrounding environment.

Ambient temperature has an indirect relationship to your fermentation temperature through heat exchange by acting as a heat or cooling source. In the simplest possible terms, the liquid in your fermentation vessel will be (approximately) the same temperature as the ambient air temperature.

Placing your fermenter somewhere that has an air temperature that is typically hotter than the target brewing temperature will result in increased temp.

Equally areas with large temperature swings perhaps between the day and night could also adversely affect your brewing process.

As a side note always avoid placing your fermentation vessel in areas that are exposed to direct sunlight. In addition to temperature control you could also encounter problems with ‘light strike’ which will also create off-flavours in your brew. 

The process of fermentation will also increase the temperature of your brew. Fermentation is a (natural) chemical reaction that generates heat because of the process. As a general rule, I would say that fermentation will at 1-2 degrees celsius to your brewing temperature, over the average ambient temperature. 

Brewing without temperature control

You can successfully brew good beer that your friends will drink with you, without any form of temperature control – but you do have to be flexible.

As a rule of thumb this would lead you to brew more ales over the summer and lagers in the winter. Spring and Autumn often offer perfect brewing temperatures.

Brewing kits

If you look at different brewing kits, you will notice some have different ideal temperatures for fermentation. 

For example, the Mangrove Jack’s Craft Series Juicy Session IPA has an optimal fermenting temperature of 18-23 degrees whereas the Kviek IPA (based on the yeast) has a suitable fermentation temperature range of 20-40 degrees and an ideal temperature range of 30-40 degrees. 

The recommended temperature ranges are based on the use of different yeast strains, that are designed to support different styles of beer.

Choose brewing kits with a recommended brewing temperature that is suitable for the season you are in. What I mean by this is look at the recommended fermentation temperature for a kit and select kits with ideal temperatures that are similar to the ambient temperature of your current season.

This is exactly how I brewed for a couple of years.

Premium yeast

One of my biggest suggestions is to disregard the ‘stock’ yeast that is included and purchase a premium yeast for your brew.

Craft yeasts offer several advantages and often help improve the flavour characteristics of your beer as well as give you more flexibility with temperature control.

Most of the time craft yeasts also have an ideal range and then a wider suitable range which can give you more control within your ambient temperature. For example:


SafAle US-05 yeast has a suitable fermentation temperature range of 12-25 degrees and an ideal range of 18-22 degrees.

Mangrove Jack’s M12 Kveik yeast has a suitable fermentation temperature range of 20-40 degrees and an ideal range of 30-40 degrees. 

SafLager S-189 yeast has a suitable fermentation temperature range of 9-22 degrees and an ideal range of 15-20 degrees.


If you use premium brewing yeasts, use the temperature range on the yeast instead of the kit.


Starting to use temperature control in your brewing

If you are brewing year-round, and you are trying to achieve a better final product or a more consistent final product you may want to consider temperature control.

I have moved to using a home made temperature controlled environment which in effect is the combination of a fridge, heat pad and an automated temperature controller. But you can achieve good temperature control using basic methods and equipment. 

Unless you have a temperature-controlled environment to brew with, avoid fixating on a target temperature and be ok with a range within 2-4 degrees Celsius.  

I would also suggest being open to where you place your fermenter in the house. I found my basement garage great over summer but too cold in the winter when I tended to find a spot in the house (subject to my wife’s approval).

Watch for temperature swings and try and find places in your house which have a relatively stable temperature throughout the day and night. 

Temperature control for brewing in Winter

For winter I would look at a heat pad and a timer from your local hardware shop. 

The heat pad may not need to be on all day, and I often used a timer set to come on during the coolest parts of the night only. This is a little trial and error and how long the timer was on for daily changes throughout the seasons. You will have to check your fermentation temperature at least daily and adjust the running time of the head pad as required to raise the fermentation temperature, or let it drop down.

It’s far easier to control target temperatures when you’re trying to warm the fermentation up. Brewing in summer – when the temperature is too hot is often a different challenge.

Temperature control for brewing in Summer

The challenge you will most likely have in summer (unless you are using the Kveik yeast) is cooling your brew down during fermentation.

I have a brewing fridge that has the shelves stripped out and is big enough to house my fermenter.

The approach is the opposite of the heat pad. You still use a timer expect this time the fridge is turning on and off to support your target temperature range. 

I went a number of years without using a fridge. How committed you are to the quality of your finished product may also determine what lengths you are prepared to go to, to cool your fermentation temperature down. Before my fridge I have been known to tape ice packs to the outside of the fermenter each morning and I have heard of people sitting their fermenters in ice buckets.

When you decide to get serious about temperature control

If you have a fridge and a heat pad your only a step away from your own ‘temperature control room’. All you need now is a dual temperature controller and with some handyman skills you’re in business. 

Mangrove Jack’s used to have a stock dual temperature controller which at the time of writing this article was discontinued. I use an Inkbird ITC-308 which also has a wifi model available. 

How much effort and focus to place on temperature control

Will effective temperature control help you create a better final product and produce more consistent results. Yes.

But what you define is good and what you aspire to in your process is up to you.

How much effort or focus you want to place on temperature control (or any other aspect of the brewing process) is up to you. Do what feels right and brew how you enjoy brewing.

And remember brewing is a journey. Many brewers go through periods where they want to experiment or improve the quality or consistency of quality of their final product. If this is you, and you are looking for more control over your brewing process then at some point you will most likely be drawn towards more precise temperature control. 

Remember that I started brewing in the ambient temperature with no control and then over time I added to my approach. It was at least three years before I started using a fridge and then another year after that before I added a temperature controller. 

Can we ask you a favour?

Our goal is to help you make good brews that you enjoy drinking, and if you want to share that your friends and family will be happy to drink with you.

Would you take one minute to give us some comments on this article? Your feedback helps us improve our content. 

And if there’s anything we missed we’re always happy to drop you an email. 

Cheers, Russell 

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