Fermentation temperature: Room vs Wort

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iXanadu

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Hi,

My house temperatures vary in the summer from 70's to mid 80's when we are away. For my last several batches, I've created a "fermentation" room by dedicating a spare bedroom and installing a window air conditioner. I can keep the temperature between 68-72 with with most peeks at 70º. Yesterday the "room" temperature was 72, and wort temperature was 76. Today after work the room temperature was 64 and wort temperature was 68. The difference was my wife ran the house air in the afternoon because it was raining outside.

I recently researched S-04 and got the opinion that folks referring to fermentation temperatures are talking about controlling the temperature of the wort - not the room. If it is wort temperature I have to regulate to 65-68, I have more problems. I've looked at the various swamp coolers, ice bottle cooler boxes and such, but it seems there isn't any home grown system that will be able to hold the wort temperature steady when it hits a hard ferment.

Comments?
 
the temp of the wort/beer during fermentation is what's important. usually the temp of the room = the temp of the wort/beer. if your in the 70's and brewing an ale your good to go. my house is between 70 and 75 and there have been no issues. going into and past the 80's gets problematic, the AC sounds like a good idea to keep it steady and in a good range. no worries
 
I've got an amber ale in primary right now, sitting in my kitchen in a bare bones swamp cooler. My ambient apartment temp averages out around 80-83 during the day, 75 at night. My wort has not gone above 66 degrees since it started fermenting on Saturday.

I use an 18 gallon Rubbermaid container ($3.50 at Target). I take two medium sized stainless mixing bowls, fill with about 3/4 gallon of tap water, and place in the freezer the night before I brew. I put the primary bucket in the container after pitching yeast and fill it with cool faucet water up to about the 2 gallon mark on the bucket. As fermentation picks up I start swapping in the bowls full of frozen ice. One in the morning when I get up at 8am, one after work at 5:30pm.

The swamp cooler water actually serves two purposes: it cools the wort when you drop the ice bowls in, and it insulates against warmup the rest of the time after the ice has melted. Surrounding the fermenter with water means warmer ambient temp swings won't affect it nearly as much, since it would take much more ambient heat to raise the temp of the water enough to make the wort temp rise as well. An hour after inserting an ice bowl, the temp is down around 63-64, 12-15 hours later, it only gets up to 65-66, and this is in an 80-85 degree apartment.

My advice would be to get the swamp cooler going, drop in two ice bombs per day and keep an eye on the liquid temp inside the swamp cooler. At peak fermentation within 72 hrs of pitching, the exothermic reactions mean the wort can be 5-8 degrees higher than the water temp, but if you're down at 63-66, you're still in reasonable territory. Plus you won't have to use electricity to run a window a/c, all you need is the $3.50 bin and a couple mixing bowls in the freezer.
 
Use a swamp cooler with frozen 2 liter bottles. Replenish the 2 liters into the swamp cooler water as necessary. After the first few days of active fermentation, the exothermic reactions will calm down a bit.

I have a basement with ambient temps in the mid 60's in the summer. I still use a swamp cooler to keep the ferment temps in the lower 60's

Cheers.:mug:
 
OK, so sounds like its Wort temperature I'm trying to keep in the mid 60's, even at the height of ferment activity. I'll look into some form of a swamp cooler for my next batch.

The follow-up question is "how long". I typically primary for 3-5 weeks and go directly to a keg. After the first week, I usually don't notice any visible air lock activity, but some fermentation must still be going on, because I'll drop several more points by week 3+ (generally 1.18ish to 1.10ish). Do I control wort temp the entire 3-5 weeks, or just during primary ferment.
 
I wouldn't worry about too much after the first 5-7 days. Depending on the starting gravity and level of fermentables you should have the ferment done by then and the rest is just the yeasties cleaning up after themselves. After the majority of work is done temp control is not as crucial and the exothermic activity is at a minimum so if its just sitting at room temp it should be fine.
 
Exactly. I use the yeast manufacturer's websites all the time- an excellent resource, by the way! So, if your yeast strains' stats say, "optimum fermentation temperature 62-69", they are talking about the beer temperature during fermentation. The room can be up to 10 degrees cooler, in order to keep the fermentation temperature at a good range for the yeast. That's no doable for many of us, so in the summer, I resort to a cooler with a foam lid I made and a water bath and frozen water bottles. (Pictures in my gallery). With this set up, I can keep a steady temperature of whatever temperature I wish.

Another thing I learned that even if you're in the optimum fermentation range, you can have very different flavors from the different extremes. For example, a beer fermented at 60 degrees with Nottingham is clean, and "neutral" and almost lagerlike in character. The same beer, same yeast, fermented at 72 is fruity, and can be almost fusel-ly in character.

I think there are two things that have made my beer better- temperature control, and pitching the correct amount of yeast. Both of those can be very easy to do, but are usually the most frequently overlooked aspects of beermaking.

Now, if the beer gets over 72 degrees, it's NOT ruined! It just means that there may be some fruity flavors or some other flaws. It might taste fine, and it might even be desired (like in some Belgians). Unless you know a beer snob friend who can pick out the esters and some phenols, it might not even be noticed. But I notice flaws in my beers, and do my best to control the things I can. So often, I'm worrying about water chemistry, sanitation, ingredients, grain crush, etc, but sometimes the biggest keys to a great beer vs. a good beer are simple, like temperature and yeast pitching!
 
Yooper_Brew said:
Exactly. I use the yeast manufacturer's websites all the time- an excellent resource, by the way! So, if your yeast strains' stats say, "optimum fermentation temperature 62-69", they are talking about the beer temperature during fermentation. The room can be up to 10 degrees cooler, in order to keep the fermentation temperature at a good range for the yeast. That's no doable for many of us, so in the summer, I resort to a cooler with a foam lid I made and a water bath and frozen water bottles. (Pictures in my gallery). With this set up, I can keep a steady temperature of whatever temperature I wish.

Another thing I learned that even if you're in the optimum fermentation range, you can have very different flavors from the different extremes. For example, a beer fermented at 60 degrees with Nottingham is clean, and "neutral" and almost lagerlike in character. The same beer, same yeast, fermented at 72 is fruity, and can be almost fusel-ly in character.

I think there are two things that have made my beer better- temperature control, and pitching the correct amount of yeast. Both of those can be very easy to do, but are usually the most frequently overlooked aspects of beermaking.

Now, if the beer gets over 72 degrees, it's NOT ruined! It just means that there may be some fruity flavors or some other flaws. It might taste fine, and it might even be desired (like in some Belgians). Unless you know a beer snob friend who can pick out the esters and some phenols, it might not even be noticed. But I notice flaws in my beers, and do my best to control the things I can. So often, I'm worrying about water chemistry, sanitation, ingredients, grain crush, etc, but sometimes the biggest keys to a great beer vs. a good beer are simple, like temperature and yeast pitching!
Click to expand...

I know its old but thanks yoop, that was exactly what i needed!!!!!
 
I use an old picnic cooler for glass carboys and a rubbermaid bin for my plastic bucket sinc eit doesn't fit inside the cooler. The picnic cooler with minimal and sporadic ice additions (a few ice cubes, stuff like that), can keep my wort in the 14-15C range for a whole week, even during fermentation. I needed to be careful about adding too much though, since from the tests I conducted, I could drop temps in the 6-7C range very easily, wich can stress ale strains and produce undesirable results...

If you use something that does not have any form of insulation and needs more water/wort level in carboy (such as a storage bin), you'll need to add more ice regularly but should be less concerned about overcooling as long as you are sensible about your additions due to the higher water volume.

A wet t-shirt wrapped around the vessel will also minimize temperature swings and block light.
 

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