Internal vs External Temp: Fermentation Running Hot

[Eiffel]

For the past two brews (pumpkin porter and APA) using 1076 and Wyeast Scottish Ale 1728, I have noticed that the fermenter is running hot.

My fermentation closet is stable around ~68F and I use a starter from slurry as my yeast. About 3 hours after pitching I start getting good fermentation with a fermenter temperature of ~80F. I have put a wet towel over it overnight which drops the temperature a couple degrees but until fermentation completes the beer stays around 80F and then drops to room temp.

No matter what I read, I cannot figure out if this is just that my yeast is happy and roaring away or if there is something wrong. If it was one strain of yeast I would just dump it and start another house blend but after the second brew with a different yeast, I thought it would be best to come here.

Some additional information:
Temperatures are determined by an infrared laser gun that is calibrated
I have not tasted any of the beer because I just kegged the first one (pumpkin porter) where this happened.

Thanks for any help! :rockin:

 

[porterpounder]

Fermentation can create a significant amount of heat with a healthy pitch. A 68 F space can easily get a fermenter up in the 80s. Try the wet shirt sitting in a bucket so the continuing wicking of water and evaporation will cool a bit more efficiently. You really only need to keep that fermentation temp down for the first 2-3 days in most ales, then you can usually let it go within reason.

 

[IslandLizard]

Your yeast will ferment faster at higher temps, which again raises the temps more, etc. But that binge will cause all kinds of off flavors and fusel alcohols, none wanted in good beer. You should bring those temps down, especially during the first 4-10 days, depending on the gravity of your beer. Aim at 65F or a few degrees lower.

Aside from a "fermentation fridge," I have a small bathroom on the lower level where the ambient temps are 63-65F pretty much all year round. But I still use a large Igloo cooler there half filled with cool water in which I can place 2 fermentation buckets. I "dope" that water jacket with frozen bottles of water to keep the temps around 62-65F depending on the beer, until the fermentation is about 80% done, then let it naturally rise, bring the fermentors to a warmer part of the house, or put a small temp controlled heating element in the cooler.

 

[Eiffel]

Thanks all! I ferment in the coolest part of the basement and did not see this happen last year. I must not have been paying attention.

Now to find a cooler big enough to fit a big mouth bubbler!

 

[IslandLizard]

Thanks all! I ferment in the coolest part of the basement and did not see this happen last year. I must not have been paying attention.

Now to find a cooler big enough to fit a big mouth bubbler!

Not sure about the accuracy of laser gun thermometers. I stick to an old fashioned long stem analog one to measure the actual beer temp in the bucket through the airlock/grommet hole. A thermowell can help too in constant monitoring, but after doing it once, you know your system.

I think the huge thermal capacity of the large water jacket helps in draining off heat created in the fermentor faster than air can, while keeping the temps more constant too. But fermentation fridges work great too, as long as you don't overshoot the temps too far, so keen placement of the probe is essential for those.

I happen to have this huge 120qt (?) cooler. A big (e.g., 19 gallon) storage tote can be used too, as long as the ambient temps are close, say, within 5-7 degrees of your intended ferm temps. Or wrap some insulation around it. Fill with water until the fermentor just starts to come loose from the bottom (starts to want to float). I use 2-6 frozen pint bottles and refresh once or twice a day. I keep the whole system "insulated" with some large towels and blankets to limit evaporation and exposure to the ambient air.

 

[MrBJones]

Try one of THESE. I got one a few months ago, have fermented my last three batches - five gallon carboy each time - in it...have to say it works as advertised. I use frozen gallon milk jugs because they last longer and in my opinion lend more stability to the temp; I start off with two, then when fermentation slows (and there's less internal heat being generated), I go to just one...regardless of the number, I swap them out for new ones once a day. Sure, a fridge would work better but this is cheaper, and it can be put away when not using. Lots of room inside, you'll have no trouble fitting a carboy of any size/sort and milk jugs. I easily fit all of that and a blowoff setup.

 

[Eiffel]

Great! Thanks!

Well I left the brew bubbling away and when I got home +24 hours from pitching and the Krause has dropped, temp has drifted to ambient, and there is no activity. I'm at a complete loss for this "easy brew" I set up for myself!