Ambient temp vs. beer temp during fermentation

Hey just wondering about fermentation temps. Let's say I want to ferment at about 68... are we talking about the temp of the room, or the temp of the actual beer? Should I keep the beer in a room with a lower temp or higher temp than I want to be fermenting at? And temp is really only a concern with the first part of fermentation, right? The rest of the time it's in the primary clearing up, the temp can go up a bit without problems, correct?

you want to be talking about the temp of the beer.

So if you want to ferment at "68" you likely want ambient temp to be around ~63 (obviously lots of factors apply) as fermentation is exothermic (creates heat).

Once fermentation is done, temp is not as much of a concern, but you obviously wouldn't want it to get really high or really low...

dandw12786 said:

Hey just wondering about fermentation temps. Let's say I want to ferment at about 68...

1. are we talking about the temp of the room, or the temp of the actual beer?

2. Should I keep the beer in a room with a lower temp or higher temp than I want to be fermenting at?

3. And temp is really only a concern with the first part of fermentation, right?

4. The rest of the time it's in the primary clearing up, the temp can go up a bit without problems, correct?

Click to expand...

Ill take a stab at this one... I numbered for my "effeciency."

1. beer
2. lower, the fermentation is exothermic.. so it gives off heat.
3. Id say temp is a concern throughout fermentation.. but you probably only have to drop the temp of the ambient for the first bit..when the yeas is really active.
4. I keep it at ferm temps until I rack to secondary, then I just leave it at room temp (68).. but, if no secondary, id say once your gravity is stable, you can probably relax a bit on the temps.

It varies from batch to batch, but fermentation produces heat, so your beer will be warmer than the ambient temperature. I use a stick-on thermometer on the fermenter to keep track of the temperature if I'm leaving the fermenter out in the room (in my basement, the fermenter temperature usually reads between 65 and 68.) Or a floating thermometer if I'm using my water/ice bottle cooler to ferment at lower temps.

dandw12786 said:

Hey just wondering about fermentation temps. Let's say I want to ferment at about 68... are we talking about the temp of the room, or the temp of the actual beer? Should I keep the beer in a room with a lower temp or higher temp than I want to be fermenting at? And temp is really only a concern with the first part of fermentation, right? The rest of the time it's in the primary clearing up, the temp can go up a bit without problems, correct?

Click to expand...

You want to have it be the temperature of the fermenting beer, not the ambient temperature. In a warm room, the fermentation temperature can be as much as 8-10 degrees warmer inside the fermenter than the ambient temperature. In a cool room, the temperature may be very close to the same or only a couple of degrees warmer. Fermentation itself produces heat, and it gets even hotter in a warm environment. In a cooler environment, it's more slow and steady. I have a couple of stick-on thermometers, called fermometers, for the outside of my fermenters so I can see the temperature.

I've heard that some people only control the temperature during primary, but I control the temperature the entire time. It may not hurt the beer much to let the temperature rise, but I don't see the benefit of uncontrolled temperatures after primary. A few degrees is fine, and a good idea, if you're going from say 65 degrees to 68. But I wouldn't ever let the beer get above the yeast strain's optimum fermentation temperature.

The fermentation temperature usually depends on the yeast strain you're using. Some strains are pretty forgiving of 70+ temperatures, but some are not.

Awesome, thanks everyone!