Temperature fluctuation in primary

[NoBrewsIsBadNews]

Hey all, new to the forum. Got a few batches under my belt, but still quite the noob. Just recently moved on to partial mashes and have run into some problems, off flavors, etc. Batch I have going now is a slightly hopped hefe using WLP300. Pitched the yeast at around 70 and within 12 hours the airlock was jumping. All was well until I noticed the temp started rising, and is now around 75-76. Temp of the room remained constant (around 70), so could this just be the exothermic reaction going on? Potential for off favors? Any input would be lovely.

Thanks!

 

[Corey_SS]

Yeah that's the yeast doing that. That's too warm; it'll still be beer and it may even be good beer, but it won't be as good as it could have been. At that temp you're gonna get those fusel alcohols that aren't too fun to drink, especially the next morning.

In the future you may wanna stick the fermenter in a tub of water to help even out the temps better. Ideally you'd be able to ferment it at a cooler ambient temp, and with the temp of the beer itself in the mid 60s for most ales. WLP300 says 68-72 but for me personally I'd still go a little cooler than that. Do you have a colder room you could use later?

 

[NoBrewsIsBadNews]

Damn, that's what I thought. The temp has gone back down since last night when it was 75ish all the way down to 68, but I'm guessing that's still not ideal because of the rapid fluctuation. But, it is better to keep it at this lower temp throughout the rest of the fermentation, correct? I do have a basement where is as thinking of putting my next batch, much cooler down there. Smart to just move my primary down there now?

 

[Math0]

He said it all! You should check on internet the perfect temperatures for the kind of yeast you use and follow them. Always go a bit lower to leave a small range for the temperature rise while fermenting.

 

[kombat]

But, it is better to keep it at this lower temp throughout the rest of the fermentation, correct?

It's better, but I'm afraid at this point the damage is done. The first 3 days of fermentation are the most crucial, as that's when the majority of the flavour compounds (and esters and fusel alcohols) are produced. Keep it in mind for your next brew and I'll bet you'll notice a big improvement in the flavour.

 

[NoBrewsIsBadNews]

Got it. Thanks fellas, very helpful!

 

[zdbrown1]

Grab a couple of rubbermaid containers that are big enough to fit your fermenters. Fill them with water and add frozen water bottles to it a couple times a day to control your temps better. Not a perfect solution but better than nothing.