I haven't done any brewing this summer because when I brewed some mead last summer, my apartment was very warm during the days, and I think this higher brewing temperature was related to some solvent-y flavours that some people detected in that batch.

I'd like to start a batch now to be ready later in the fall, but it's still rather warm (gets close to 30C indoors in the daytime) in my apartment. I don't have a budget for a temperature controlled fermenter. I make small batches (5 Litres) and the fermenting jar will fit nicely into a small picnic cooler. My plan was to put a few freezer-packs into an inch of water inside the picnic cooler to lower the temperature overnight and then put the fresh wort in the next day (in contact with the cold water at the bottom to keep it cooler). I imagine I'd have to change the freezer-packs twice a day.

Is this a good idea? I know that the process of fermentation itself will generate a little bit of heat and while I don't think it's enough to overwhelm the freezer-packs and overheat the inside of the cooler, I'm not 100% sure about that. Has anyone used this method before? Does it work (or sound like should work), or should I wait for cooler weather?

1 Answer 1


I do something similar, I keep my fermentor in a big rubbermaid bucket filled with cold water. If I need to make it even colder I drop in water bottles that are filled with ice, as they melt, I swap them out for others and put them back in the freezer. I don't have temp controlled fermentation (yet) and this method seems to help keep the ferm temp somewhat under control. I just have a thermometer strip attached to my bucket, however the water seems to ruin these, so I tape over them with clear packing tape, this seems to make them last longer (some water still gets in and ruins them after some time though). Clearly this method doesn't beat a thermowell with a temp controller and fridge/freezer but it works in a pinch in the summer heat.

Edit: I'm not sure this matters but I like to submerge as much of the fermentor in the water (below the lid obviously) to try and standardize the temp of the wort as much as possible. I'm not sure what the effects of having only the bottom of the fermentor in cold water so that the bottom was colder than the top. I like to try and keep the temp standard from top to bottom as much as I can.

  • +1 I would recommend the same. And definitely submerge the fermentor as much as possible.
    – hartski
    Aug 3, 2012 at 17:25
  • Until I built an SOFC (fermentation chiller) this was the method I used all the time. I had great success with it. The surrounding water acts like a heat sync for the wort.
    – David PGB
    Aug 4, 2012 at 15:16

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