Fermentation Temperature Control

[triwave]

Hello,

Having minimal space for equipment I struggle in warmer weather to keep fermentation in check.

I tried a 2.5 gal fermentation bucket in a water bath of approx same volume cool water. Add ice packs moning and night and to my surprise the analog thermometer in the water is fairly constant around 68F with no big excursions.

So I have successfully maintained a water bath temp with manual method.

I guess my question is about the temp gradient one might see in the wort? I know it produces heat, but over time if the water remains constant how much different can the wort be? A couple degrees higher?

I'm trying to reduce off flavors that have crept into my last two batches...

Thanks!

 

[brew_darrymore]

68F might be a bit high as the fermentation temperature inside the fermenter could be 5-10 degrees higher. See if you could bring the surrounding water temperature down to 60-65F and you're good to go. Add more frozen water bottles, and if your swamp cooler is not large enough then get a bigger bin or bucket that can accommodate more frozen water bottles.

 

[d3track]

Put an old t-shirt over the carbon, evaporation will help cool too.

 

[flars]

Put an old t-shirt over the carbon, evaporation will help cool too.

Have a fan blowing on the wet cotton t-shirt, towel, or sweatshirt for more cooling. Protect your thermometer from the cooling breeze or it will show a larger temperature drop than is actually occurring.

 

[revco]

I think there's been tests that show ~1 degree difference between the exterior of a fermenter (taken from say, a brewmometer or well insulated thermal probe) compared to the internal temperature. The confusion comes around air temp vs. beer temp where you can see 5-10 degree higher temp differences between ambient air and the beer.

68 degrees is a pretty common and decent temp to ferment at much of the time and will probably go a long way to reduce the off flavors. Lower is often a slight bit better, but you really want to stay away from 70+ most of the time. (Some yeasts actually prefer warmer temps to get esters you'd expect in that style.) Some yeasts will show remarkably different characteristics even a small temp difference like 62 and 68.

I used to only brew in the winter and shoulder months, such that I could drop my house temps to 60 or so to maintain temps. I did use the water bath method a couple of times, but found I just didn't care for replacing the ice bottles on a continual basis for a week.

What I can tell you is that proper fermentation chambers (like say a converted freezer) are pretty awesome because they open up virtually all styles and characteristics you might be able to get from a given yeast. It also opens up options for lagers and cold crashing, which definitely help.

Hope that helps!

 

[DurtyChemist]

I put mine in a spare tub and fill the tub with water about 2 gallons up on the bucket. More thermal mass required to heat up means it will hole temps a little better.

 

[DapperD]

I started using the water bath method with my last brew, no off flavors that I was able to notice. However it was a bavarian hefe with a strong yeast taste so I was a bit worried since I've never had it before. However I brewed this kit for a friend and he said it tasted almost identical to something he had in at a bar before. So it seemed to work fine for me.

I've understood the temp delta to be up to 10 degrees as well but only during active fermentation and 5 or less as it tapers off.

My current bucket in water is a marris otter/cascade SMASH using safale us-05 yeast which ideal temp range of 59-71 degrees, so I shot to keep it 63-65 ballpark. So during active fermentation I tried to keep the bath temp around 55-58. I actually stalled it at one point after about 2 days and had to warm it up a few degree and light swirl to fire things back up.

It defiantly requires your attention a couple times per day but is easily manageable and will help to avoid off flavors that make all your hard work feel pointless when they're present.

 

[triwave]

I bottled the porter today and a little taste seemed quite nice. No strange tastes that aren't supposed to be there!