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Joechianti

Fermenting temp question

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Okay, I'm using the coolers and ice packs to control the temp on the LBK's. Works real good but there's one concern I have. Between the time you are able to swap out the ice packs, you can get an easy 10 degree fluctuation.

I'm getting down to 60 when I first put the bottles in, but up to 70 by the time I replace them again. Have to work and sleep, so more frequent changes is not so practical.

What I'm thinking is that I should step down to a cooler range with more ice packs. Say I get it down to 55 and it gets up to 65 before I can change them again.

Is the same 10 degree fluctuation less harmful in that range than in the higher range? I hope so, as it would be an easy solution.

Anyone know if this is correct or not?

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I'd say it depends on the yeast you are using. Personally for most ale yeasts I think that 60-70 is better than 55-65 though

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"JonEleven" post=267815 said:

I'd say it depends on the yeast you are using. Personally for most ale yeasts I think that 60-70 is better than 55-65 though

Agreed. While we know most ale yeasts just go to sleep when it gets too cold, rather than emit off-flavors when they get too hot, I still think I'd rather risk off-flavors than keep delaying, prolonging, and even stopping the fermentation process, especially during primary fermentation.

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Joechianti, how many ice packs are you using? Do you change them all out at once?

I'm going to be using a cooler pretty soon too, so I'm very interested in what you're trying right now.

It seems to me that having as many small units of ice in there as you can fit would help achieve a more consistent temperature. If I were to use one ice pack in the cooler to get a desired temp, and swap it out with a frozen one from my freezer when the temp in the cooler gets too high, I'd probably get on a temperature roller coaster. If I had two ice packs in the cooler, they might have to be smaller to hold the cooler at the same temp as the previous one ice pack, but I could change one of the smaller ice packs out on a regular basis, and get a rotation. With a little practice and note taking I could probably get a feel for how often I should rotate one of the packs out. If I had three tiny ice packs, I'd achieve more stability. Four icepacks, perhaps more stability still.

Any thoughts out there in the :borg: as to wether numerous water bottles would allow better control than a few icepacks?

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Just to be clear, are you seeing that big of a swing in the air temp in the cooler, or in the beer temp? I use a cooler and frozen water bottles and can keep the beer at a pretty much even temperature (maybe a swing of 1-2 degrees tops) swapping out morning and night, maybe three times a day when fermentation is vigorous. How big of a cooler are you using?

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Perhaps some more insulation around the ice? You say you're using a cooler. I have my carboy in a giant pot and it leaves room for ice packs and bottles around the carboy but inside the pot. Then I have towels around the outside to further insulate the ice.

Mine does not fluctuate as much. It gets to 72 and I can knock it down to 67. Then again, I have not done this yet during a real heat wave. I'm doing fine since it's getting to about 80 every day. Once we get some 95 degree days it could be a game changer.

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KZ,

Good question. I am reading the air temp. I do figure the temp of the wort in LBK is not fluctuating as much as the air is, which is a good point.
I'd bet the wort is not as high as 70 just before I change the bottles and not as low as 60 right after.
[edit] I'll have to use the probe thermometer to confirm this. Dumb stick ons won't give any reading below 66. Hate that fact with a passion.

Jason,

I've been using 2 half-liter bottles in a 48 qt cooler. They usually keep the temp down in the 60's for almost 12 hrs. It's getting hotter here lately and I guess I need to adjust. Was 100 yesterday. Haven't looked at today's weather yet.
I'm thinking like you, maybe more bottles, partially rotated instead of all at once, might help soften the swings in temp. Problem is between work and sleep, I'm either available too soon or too late. I can't be on it every 6 hours. I'll figure it out. You will too. The coolers are a wonderful deal, you just have to find the right routine for your location.

Jon and Dave,

As KZ pointed out, I forgot to specify that was air temp, not wort temp. So hopefully the swings are actually less in the wort. I assume it cools down slower and warms up slower than the air does from the influence of the frozen bottles.
It sounds like you guys are thinking the same amount of fluctuation, if I have a choice, may actually be safer in the 60 to 70 range than in the 50 to 60 range.
I always hear that temp fluctuations can cause fusels and off flavors just like high fermenting temps can. As long as it never goes above 70, does that minimize the impact of temp swings on off-flavors?

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The wort will change temperature far more slowly than the air, so you're probably only looking at a slow up/down swing of a degree or two, nothing I would worry about as long as your base temperature is good.

Cheers!

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It's doubtful that the actual liquid (wort)would fluctuate that much in that time as it takes time for 2 gallons of liquid to change but the ambient temperature in the cooler may change that much.
I've found in my ice chests that the ambient temp of 59 (after 2 days of fermentation) is actually about 65 in the LBK. Then, as fermentation slows down, after about another 3-5 days, the ambient temp in my cooler is 61-63 and the LBK temp is 65-67. By the third week of fermentation, assuming I'm still swapping out twice a day with the same amount, the ambient temp is much closer to the LBK temp.....about 61-62.
It's the first few days that I find hard to gauge due to the time it takes for my cooler to chill down the new, warmly fermenting LBK.

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