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Old 07-01-2008, 01:01 AM   #1
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Aug 2006
Whitehouse Station, NJ
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If you've ever heard people say how controlling your fermentation temps are a huge step to improving your beer, you've probably given it some thought. You may have also concluded that keeping the primary in an area with ambient temps in the general safe temp zone was good enough. Not really.

The first thing you ought to do is get some stick on thermometers to get a reasonable idea of what temp the wort is.

Fermentation kicks off a lot of heat so the wort is always going to be hotter than ambient during the active period. Just so you know I'm not just spouting off things that have been said in the past, here's proof.

This is my fermentation and cold conditioning fridge. On the top shelf you'll see some American Amber that is done with active ferment and has been transfered to secondary for aging and clearing.

On the bottom shelf is a Barleywine and ESB that are at peak fermentation "high krausen" having been pitched on yeast cakes two days ago.

Right, so what?
Here's what temp the Barleywine is running:

Here's the amber:

Yeah, the actively fermenting beers are 10F hotter. You might guess that it's because they're in different elevations in the fridge but think about it. Heat rises so if anything, the top beers would be warmer.

The moral of the story is that you can't assume that a reasonably comfortable ambient of 70-75F is anywhere close to cool enough for fermenting. Maybe you knew that. If not, this post is for you.
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Old 07-01-2008, 01:32 AM   #2
Jun 2007
smAlbany, NY
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I will 2nd this. I have noticed a huge difference in how good my ale tastes between keeping it in ambient 70 degrees in the closet upstairs and the ambient 60 in my basement.

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Old 07-01-2008, 02:26 AM   #3
Jun 2008
Cavan, Ont. Canada
Posts: 5

I also agree. I use a temp controller in my freezer and set it usually around 62F for ales. Sometimes I have to lower it more than that when it goes over 70F. I do, however raise it to around 65F when activity slows down.


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Old 07-01-2008, 02:31 AM   #4
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Feb 2008
Amherst, Western New York
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I just finished my keezer for the most part and was thinking about doing a lager now, However that means that I cannot do any ales. My apt temp varies by 20 degrees easily over a few hours and although the basement stays at a nice 69 during the summer that is still a little hot considering all the heat that active fermentation throws. And this is why we have apfelwein!
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Old 07-01-2008, 03:43 AM   #5
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Apr 2007
Oakland, CA
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my ale fermentation cabinet will be staying at a steady 56°F ambient temp, leaving the beers to go no higher than 65°F. can't wait to get that thing up and running, i'm almost finished with the door and then she's good to go!
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Old 07-01-2008, 04:06 AM   #6
Eastside Brewer
Feb 2007
Posts: 328
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I have a fridge with tepm control, but have been experimenting with keeping tepms. Is there a general range between beer temp. and ambient temp of the fridge? Is it 10 dgrees diff.? I thought at first that the two temps would match, NOT! The controller I have is a single stage, so I have put a small light bulp in the fridge and turn it on and then set the fridge to a colder temp than the desired ferm. temp. Is this how others are doing it?


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Old 07-01-2008, 04:46 AM   #7
Bearcat Brewmeister
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Feb 2006
Cincinnati, OH
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Bobby, I'm really glad you posted this. So many people worry about getting the right recipe or mash temperature or numerous other things, but a non-optimal fermentation can screw the pooch on what was up to that point a top notch beer. It is probably the biggest difference between making a good beer and making a great beer. Do you ever wonder how the guys that win all sorts of awards at competitions in multiple categories do it? Look at NHC and what you have to go through to win a category - beat out 20 to 30 beers at regionals then do it again against the best of the best in round two - yet some guys win multiple categories and it seems to defy the odds. These guys have very controlled fermentations. Jamil says it is the most important part of making beer and there is no way you can argue with his success.
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Old 07-01-2008, 08:01 AM   #8
Sep 2007
Sheffield, UK
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Originally Posted by Bearcat Brewmeister View Post
Bobby, I'm really glad you posted this. So many people worry about getting the right recipe or mash temperature or numerous other things, but a non-optimal fermentation can screw the pooch on what was up to that point a top notch beer.
+1. Great post Bobby. The only beer I've ever totally f**ked up was my first, which fermented in a room that was about 72F. I thought that was fine, but hadn't taken into account the heat from fermentation. The beer stank of bananas and was kind of gross. So I second everything you and BB have said.
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Old 07-01-2008, 08:24 AM   #9
May 2008
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+3 (if that is possible) on this post, I used to use a small fridge to control the temp, when it busted I went back to swap cooling methods. I can tell you the difference was highly noticeable. Finally bought a new fridge and using the old POS as my fermenting chamber. I'm back to making good beer now and striving for great beer with all grain.

Side note, thanks for all your postings, they helped me a lot. I just wish I could fit four carboys in mine like yours. (jealousy rising).
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Old 07-01-2008, 08:51 AM   #10
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Jun 2008
Ventura, CA
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Great post.

I'm using the icewater bath & towel trick for now, and there is indeed a 10-15 degree difference between the water and the beer. Thankfully, I've gotten the ice water to where I pretty much throw one big blue ice pack into the water twice a day and it keeps things nice and rather steady.
I never did like to do anything simple when I could do it ass-backwards...

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