Cool Brewing Fermentation Cooler Bag

Cool Brewing Bag Review – Is It Worth the Money?

This is a review of the Cool Brewing Fermentation Cooler Bag.

When you want to step up your brewing game but don’t want to invest into a dedicated fridge, grab a fermentation temperature control bag

That was my situation. I bought the Cool Brewing bag and after several uses, I can soundly recommend it.

In this review, I will go through the features of this fermentation cooler bag and show you how it can improve your next batches of homebrew.

Let’s get started.


Cool Brewing Fermentation Cooler Bag Overview

cool brewing bag and me
That’s a happy user of the Cool Brewing bag!

This bag works exactly like a cooler. Yes, like the one you take to go camping.

It is insulated, which means that if you put ice in it, the inside of the bag stays cool.

Why is it good for homebrewers?

You can keep the temperature of your fermenting beer under control during the hot summer months or if you live in a tropical place where the ambient temperature isn’t suitable for a healthy fermentation (usually below 73° F or 23° C).

And if you’re reading this, it means you know that fermentation temperature is key to making a good beer.

I was actually very surprised to read in How to Brew that John Palmer considers fermentation temperature control to be the 2nd most important thing (after Sanitation, #1) to make great beer; not the recipe, not the gear.

That’s when I decided to look into a solution to manage my fermentation temperatures better.

With the Cool Brewing bag, I’ve been able to keep my fermentation temperature in the range of 64 – 70°F (18-21°C) in summer.

cool brewing bag inside
The inside of the Cool Brewing bag. There’s a simple zipper to open the bag


Pros and Cons

Pros Cons
Easy to keep the temperature cool (with bottles of ice) At first, a bit difficult to manage the temperature in the bag
Lots of space in the bag (for at least two 5-gallon carboys or buckets) Need to change the ice often (at least once a day)
Easy to clean
Takes less room than a dedicated fridge. Can be folded and put away when not being used.


Main Features

  • Keeps a low temperature. It keeps the temperature low for a decent amount of time. I found out that what works the best for me is to change the bottle of ice once a day. Usually the bottle(s) are not completely melted but almost.
  • Keeps the beer in the dark. No need to put it in a dark closet, the bag allows no light.
  • The bag is foldable, easy to clean and put away when not in use.
  • Can fit at least two 5-gallon fermenters. The diameter is 20.5 inches (52.1cm), I didn’t try but I think you could cram a third one in there. It’s quite tall, 26.4 inches (67.3 cm) so it could also fit a conical fermenter.


How to Use the Cool Brewing Bag 

I freeze bottles of water of 1 L or 1.5L and leave them inside the Cooler bag next to the fermenter.

I also stick the thermometer to the fermenter allowing me to know if I hit my target temperature.

cool brewing bag termometer
I stick the thermometer on the fermenter to get the most precise temperature possible of the beer
cool brewing bag temp check
I use this kind of thermometer to compare the temperatures outside and inside the bag

It took a bit of tweaking over the first few days to get the temperature I wanted inside the bag. Basically, I was putting in too many iced bottles so the temperature went down too low inside the bag.

I found out that 1L of ice for 1 day would lower the temp 5 to 10° F (3 to 5° C) inside the bag than outside.


The Experiment

I made an experiment and took some readings several times per day for 2 weeks for this beer in fermentation to compare the temperature inside and outside the cooler bag.

For your information, the beer was a Double IPA and the recipe I was following was calling for a fermentation temperature of 68° F (20°C). In the month of May, the temperature in my Barcelona flat was already a bit high, around 73-77° F (23-25° C).

Here are the results:

graph bag temperature readings
Temperature readings taken over 2 weeks inside and outside the Cool Brewing bag (click to enlarge)


Changing the Ice

Open the bag, remove the melted bottle of ice and replace it with a new one.


This Cooler bag does take less room and money than a dedicated fridge, but the drawback is that you constantly have to change the ice. Once or even twice a day depending on the outside temperature.

So you can’t really go on a vacation, leave it alone and forget it like you could do with a dedicated fridge.

If you don’t change the ice, the temperature inside the bag will quickly climb to the outside temperature in a day or so. And so does the temperature of your fermenting beer.



Cool Brewing Fermentation Cooler Bag Reviews

96% of homebrewers would recommend this Fermentation Cooler Bag to a friend. Over 170 reviews give this product an average rating of 4.7/5 stars on Amazon.


Fermentation Cooler Bag vs Fermentation Fridge

If you have enough room at home and the budget, I’d recommend going for a fermentation fridge. It’s easy, set it and forget it. You can be sure that the temperature will be totally stable.

But if you don’t have a spare fridge that you can transform into a fermentation chamber, you’re looking at buying a new fridge ($100-200) and an Inkbird (around $40). Quite a budget compared to the price of the Cool Brewing bag (around $70).

Also, if you live like me in a rather small flat in a city, you might not have enough space for a beer fridge. In my case, I surely don’t.


Should I Buy The Cool Brewing Fermentation Cooler Bag?

If you want to control your fermentation temperature during the summer months and not break the bank (a dedicated fridge can be pricey), then I recommend the  Cool Brewing bag.

Controlling the temperature of your fermentation is a big step towards the grail: making great beer. It surely works for me.

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