Varying Fermentation Temperatures

What are the implications of my ale fermentation temperatures varying up and down in a yo-yo pattern?

My house is poorly insulated, and when the heat comes on the thermometers on my carboys varies between 64 and 72. Of course, this doesn't happen right away, but over a period of several days, in a yo-yo pattern.

The yeast will likely become confused and may go dormant when it goes from 72 to 64. They may wake up again when it swings back up to 72. You'll also have issues with ester formation depending on the timeframe of these yo-yo patterns.

Do you have a sleeping bag or other insulating material to help cushion the swings? Or even a closet near the inside of your home?

It depends.

If it starts cooler and warms over a couple days you probably ok. If it starts hotter and cools then warms within each day you will probably have esters, fusel and other off flavor then when it cools again yeast will flocculate and maybe no attenuate fully.
imo fermentation temp. control is the most important step in brewing.

AmandaK said:

Do you have a sleeping bag or other insulating material to help cushion the swings? Or even a closet near the inside of your home?

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Even if you don't insulate with a sleeping bag, something that could work very well for you is to submerge your fermenter in a water bath in a cooler or bin. It takes a LONG time for 5 gallons of beer and 5-7 gallons of water to change temperature, so that would really help minimize temperature fluctuations.

I can't find the article that I read on this, but temperature fluctuation will stress the yeast and it may cause off flavors. Your beer would be able to tolerate the temperature change better if it was in a bucket of water.

This blog post describes the effects of a large water bath on changing temperature:
http://woodlandbrew.blogspot.com/2012/11/lagering-outside.html

Yooper said:

Even if you don't insulate with a sleeping bag, something that could work very well for you is to submerge your fermenter in a water bath in a cooler or bin. It takes a LONG time for 5 gallons of beer and 5-7 gallons of water to change temperature, so that would really help minimize temperature fluctuations.

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Just do this ^

Get a rubbermaid for cheap from Big Lots or WalMart and fill it halfway with water.

Yooper said:

Even if you don't insulate with a sleeping bag, something that could work very well for you is to submerge your fermenter in a water bath in a cooler or bin. It takes a LONG time for 5 gallons of beer and 5-7 gallons of water to change temperature, so that would really help minimize temperature fluctuations.

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Very good idea.

sure, Yooper gets to the submit button 5 minutes before me and gets all the credit.

WoodlandBrew said:

sure, Yooper gets to the submit button 5 minutes before me and gets all the credit.

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Okay, you're special too! And you get one star! nestar:

Looking back on the thread though, it's so much easier to see posts by people with bolded names/avatars. Maybe that's just me though.

AmandaK said:

it's so much easier to see posts by people with bolded names/avatars. Maybe that's just me though.

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Hint, Hint! *coughbecomeapremiumsupportercough*