When we are home three days a week, we keep the temperature at 68. It's probably slightly colder (65? most likely not below 64) downstairs where the beer will be kept.
However, when we are at work/sxhool four days a week, or when we go somewhere, we turn the heat completely off. So by the time we return home, the house could anywhere down to 50 degrees, depending on how cold it is outside.
So the question is...is there a problem if the temperature dips down into the 50's like that, which is frequently does?
When in the fermenting stage (I'm talking about the ales, not lagers), do I need to keep a very consistent temperature? How low can I let the house temperature dip to? And if it goes below that point, what happens to my fermentation?
And how about the reverse? In the summer, the house is at 74-76 when we are home, but much warmer when we're gone.
Note: I haven't brewed anything yet, just planning ahead.
consistent temperature
for the beer is indeed important - see my previous post ("100% option B...")
when an actively fermenting beer is cooled, the yeast will become dormant - it's a defense, they're all like "WINTER IS COMING!!!". they will stop fermenting, drop to the bottom ("flocculate"), and the beer will be sweet and under-attenuated with off-flavors left behind. once beer has started fermenting and stopped, it is difficult to get it going again.
on the flip side, yeast like warmth and they'll go bonkers in high heat. your beer will ferment fully, unfortunately the yeast will create a lot of unpleasant off-flavors - mostly fusels, which give beers that "hot alcohol" flavor. other possible off-flavors include bubblegum and obnoxious fruity (over-driven esters).
that being said, it's not the temp of the surrounding air that is important, it's the temp of the beer inside the fermenter that is. so, the question is: how will the beer's temp react to the ambient changes?
personally, i wouldn't feel comfortable with that big of a swing. first thing i would do is increase the mass of the liquid, by putting my carboy/bucket in a big tub of water. the extra water in the "water bath" would help stabilize the temps - it would take that much longer for ambient temps to affect the beer's temp. target/walmart/etc sell 18 to 20 gallon tubs meant for icing kegs - they work perfectly for this. in addition, you could get a cheap aquarium heater and stick that in the water around the carboy/bucket and use its temp controller to keep the water at a (relatively) constant temp.
you can use that same "water bath" technique for warmer temps, but instead of an aquarium heater use ice packs or bottles of frozen water to regulate the temp. this is a manual process, but you'll quickly get the hang of how much ice to add & how often to maintain temps. if you don't/can't use a stick-on thermometer (see below) then use a regular thermometer to take the temperature of the water bath several hours after you've added ice and assume that the bath's temp is the same as the beer's.
if you use a carboy: plan on adding a
stick-on thermometer and place it below of the level of the liquid in the carboy. then be sure that the water bath doesn't cover the thermometer, AKA keep it above the external water level. i don't know if those things work on plastic buckets, since plastic is a pretty good thermal insulator.
merry christmas!
