How critical is temperature control

This question is general and relates to nonspecified ale yeasts. How critical is a constant temperature? Can a room fluctuate say 5 or 10 degrees every day (say when using a digital thermostat to save fuel)?

Does anyone know of an a fast, easy fix for leveling these spikes when brewing? I will need something because I'll switch to wood heat again which will fluctuate temperature in the living room from 80 (early evening) to 65 degrees (middle of night). I plan on building an insulated chest, but that's neither easy nor fast. Does wrapping a fermenter in a blanket work or even help?

The best way to do something like that is to increase the thermal mass, one way I have seen is setting the carboy in a giant bucket of water. It takes a lot more heat/cold to change that total temp.

I keep my carboys in coolers filled with water. My house is a little cooler than yours (you really keep your house at 80? damn) i see only a few degrees of change using the water bath. im at 64 during the day and 50-55 at night.

i actually need to add some frozen water bottles once in a while to keep the temp down to where i want it, i usually ferment at 57-64 depending on what beer im brewing.

during the summer when temps never go below 70 i use a freezer with temp control

k47k said:

I keep my carboys in coolers filled with water. My house is a little cooler than yours (you really keep your house at 80? damn)...

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Not to hijack my own thread, but that there is the beauty of having a wood stove. You just burn the wood, get a nice thick base of coals, and then feed as needed. It just happens to get as warm as it gets. So basically if the two buckets happen to fit in an open picnic cooler, I'm set...

No wood stoves down here.

To answer your question, in my experience, variation of temps is not a problem. Jut keep temps down. Ales over 70, during the first 5 day of fermentation, can get a fruity estery flavor. Lagers, if you make them, won't be as crisp if fermented over 60.

I believe that temp control, along with pitch rate, are the two most important factors to good beer. The better the control, the more "standard" your beer is. What I mean is: temp has a huge relationship with all yeast activities. The less fluctuation your yeast experience, the more reproducable your results are.

When I started brewing, I didn't want to believe it. I said, "I like fruity ale flavors, I don't care if my beer gets hot." But I was so wrong. I really feel my beer quality improved astronomically when I got a temp control system. That was the exact moment when people started drinking my beer in disbelief that it was homebrew, SWMBO (who has an amazing palate) started actually praising my beer, and I started winning some medals.

Once you get temp control yourself, you'll be angry you didn't do it sooner.

Temp is critical, especially during lag-time and the first couple days of the ferment.

It's also noteworthy that certain strains are more forgiving with respect to temperature. I've mishandled US-05/1056/001 very badly and still had very good beer. I've also done the same with S-04 and ended up with nail polish beer.

Temperature control is very crucial regarding the outcome of your beer. Being able to keep temperatures standardized means you will be able to reproduce beers much more easily. That said, yeast also respond differently to different temperatures, so it's important to keep them in the range you desire.

Unfortunately I pitched my last beer at a temp of 80f by accident. Fortunately the temp dropped rather quickly and is hovering around 63, but who knows.