Cool Brewing Bag Review

by Karl S Updated on September 10, 2012

One thing I always stress to our Batch 1 and Beyond students it to control their fermentation temperatures. Most new homebrewers ferment waaay too warm.

Cool Brewing is helping to combat that. They invented an insulated bag made especially for fermenters. It will fit any size fermenter up to 6.5 gallon carboys and buckets.

How does it work? You put frozen water bottles into the bag, zip it up, and the bag will keep your beer cool. Simple, but smart.

I was able to try it out with my robust porter.

My experience with the Cool Brewing Bag

I cooled my beer down to 66°F as I do with most of my ales. I pitched my yeast, and let the temperature rise to 68°F. That’s when I added a one-liter water bottles.

I chose one liter bottles because I wanted more control over the temperature and was afraid that a 2L bottle might be overkill since 68°F isn’t that cold.

Fermentation really took off the next morning and I had to add two more 1L bottles to maintain 68°F. 3 bottles did the trick for the first few days. The ice melted after about 24 hrs at which time I swapped them out. Once fermentation calmed down, I was able to go down to 2 and then 1 water bottle.

Do I recommend it?

Well the results speak for themselves. Unlike the swamp cooler which required me to change out the water bottles every 8 hours or less, these bottles stayed frozen for a day and sometimes more. No more getting up in the middle of the night to check on your beer.

It takes a little practice to know how many water bottles to add, but once I got the hang of it the resulting temperature change was fairly predictable. It would be interesting to try fermenting a lager in the bag. Here is a quote from someone on this HomebrewTalk thread who’s had success:

“I am having tremendous success keeping my lager at a steady 50/52 (I use adhesive temp strips, so probably 51. Ambient temperature ~70) I froze five 3 liter Poland Spring bottles, put four in, and each morning and afternoon I replace a watery one with a frozen one. It is fermenting away, and I couldn’t be happier. This product should definitely advertise the fact it can be used to cool down to lager temps, as that would be a big selling point for folks.”
– Libeerty

Not bad. It appears that the Cool Brewing guys are also having success with heat wraps when you want to warm up your beer.

So yes, I recommend this product. It’s still not as effective as a chest freezer, but for the price, smaller footprint, and how well it works, it’s a great deal. If one of these were included with every starter kit then new brewers would see much more success with their first attempts, which we all know can be a disaster.

Check out the Cool Brewing bag

Disclosure: This product was provided free of charge for evaluation and feedback.