Ferment Temps vs. Ambient Temps

[joshesmusica]

I have this crazy yeast that I've talked about a lot. Its original owners ferment their farmhouse beers at around 40C/104F with it. I have a christmas brown ale fermenting with this yeast right now, but I only wanted it to give off a little of its typical characteristics, so I decided to ferment at around 25/77. So I set my temp controller to about 21/70, so that if it dropped below that, the lamp would turn on and heat it up. But I figured that during the vigorous part of fermentation, it would rise up to around 25/77. Boy was I wrong!

So I got this idea, that I should show the new brewers what happens if you don't control the ferment temps, or if the temperature you're attempting to control is the ambient air. Room temperature is 21/70 as I stated, I've had the lid to the chamber open this whole time. The thing is chugging away just over 24 hrs post-pitch at 27/81! And that temp probe for the temp controller isn't even taped onto the bucket. It's just hanging out at the bottom of the chamber in that corner. So the actual beer temps are probably even a degree or two higher than that.

This first picture is a Hard Christmas soda that's finished fermenting and is just "chilling" at room temps to finish up and condition a bit while waiting to be cold crashed. It's just to show what room temps are, in case nobody believed me.

The second pic is the bucket in the chamber, and the temp controller.

 

[iijakii]

Fantastic. Should be Sticky'd. Cool-ish rooms are not adequate fermentation control.

 

[Brew_G]

Fantastic. Should be Sticky'd. Cool-ish rooms are not adequate fermentation control.

But if that's all you've got, then you do what you can to make it work.

 

[cjones]

need to have that temp prob in the liquid or at least a thermal-well - took me a while to catch on to that to... also sometimes it may not be possible and some will put the prob in the blow off buckets liquid- this will not work real well either - because those yeast sure like to heat things up. - specially if you got 15 gallons going.
View attachment ImageUploadedByHome Brew1446514713.607354.jpg

 

[joshesmusica]

need to have that temp prob in the liquid or at least a thermal-well - took me a while to catch on to that to... also sometimes it may not be possible and some will put the prob in the blow off buckets liquid- this will not work real well either - because those yeast sure like to heat things up. - specially if you got 15 gallons going.
View attachment 313537

I would love a thermowell, but I don't believe it's completely necessary. I think you can still get a very close measurement from taping the probe to the bucket, and some kind of insulating material taped to the outside of it.

Though, this wasn't necessarily to show how to properly control temperatures. Just trying to give a clear example of how much more heat will be produced by fermentation, and how far off it can actually be from room temps.

 

[cjones]

completely agree bud - and yes taping to the side is the best option if a thermowell is not available - i was just trying to throw a bit of what i learned about blow off bucket liquid... I have seen some put the prob in there and I have done it as well for awhile - It does a great job of controlling that liquid, but those yeast can heat things up... now I had a new problem when i went to thermowell that was funny - the chest freezer will sometimes freeze the blowoff bucket liquid - not all the way but i get like a little ring - found best thing todo is put it on a peace of foam to not let it touch the walls.

 

[joshesmusica]

Just to really drive home the point, I thought I'd just take it out of the chamber and see what the thermostrip was reading. As suspected even a couple of degrees higher than the "ambient" air at the bottom of the chamber.

View attachment ImageUploadedByHome Brew1446515729.695875.jpg

 

[cjones]

to bad I can add a video so easily- maybe I will later to give you added help - i can video the digital read out as I move the prob from one spot to another - and show the difference in real time on a video. - think that would help?

 

[Gavin C]

very clear images and explanation.

Really nice job Josh in demonstrating the exothermic nature of fermentation.

That's a 10C increase in the beer temperature over the room temperature you're showing, yes?

 

[Calder]

It does show there is a decent temp rise during fermentation, but I don't think it is really representative of a bucket sitting in an open room.

You have the air sonewhat trapped in a small volume, and the bucket insulated by the surrounding heat reflective silver walls.

I don't have a clue as to the amount of heat it is trapping, but in an open room I would expect it to be a lot cooler. Maybe only half the temp rise you are seeing.

If I just put insulation board around a fermenter, with an open top, I would expect it to trap a decent amount of heat.

 

[brewcat]

Right now I have the most active part of fermentation going. Ambient temp is 64. Fermentation temp is 68. I'm getting around a 4 degree difference in a more open space.

 

[joshesmusica]

Right now I have the most active part of fermentation going. Ambient temp is 64. Fermentation temp is 68. I'm getting around a 4 degree difference in a more open space.

Yeah, I think it's less extreme the lower the temps get. I guess my point was to show how it can really begin to get out of hand. Since I had a yeast that I didn't mind if it did get so warm, I thought I would give examples. I'm sure a lot of people ferment in open spaces, but some people just throw it in a closet, or have it sitting in the corner of a room next to some furniture. I think both of those would also help to trap in some heat.

But, I have been wanting to see what this yeast gets like at even lower temperatures. So, next batch I ferment with it, I could either put it in my basement which is probably sitting at around 14-15C/57-59F, or I'll just take it out of the chamber. Not sure which yet.

 

[cjones]

I ferment in the living room so I can watch the airlocks bubble during commercials....

 

[joshesmusica]

Ok, update time:

1st photo - Shows that it's clearly sitting out in the full effect of the ambient temps. Practically nothing to help trap the heat in, although I had to move it close to the bed in order to get a blowoff tube set up.

2nd photo - Shows the ambient temps in the room, which are 17.9C/64.2F. The probe was placed below the stool. At first, I had the probe on top of the bucket, but that was actually (maybe even obviously) picking up some of the heat from the bucket, so it was reading around 20C.

3rd photo - Just to confirm the air temperature with a different thermometer. Glad they're both reading the same thing.

4th photo - Thermostrip reading 23C/73.4F, which is a difference of about 5C/9F.

Yeast is WLP400 pure pitch, pitched at 19C/66F. Activity started approximately 15 hours post pitch. OG 1.050, 25L/6.6G, so nothing terribly crazy. If it was the same amount of sugars in 5 gallons, it would be 1.066 OG, so I just made it into the requirements for direct pitching the pure pitch packet. Manufacture date was Nov 1.

 

[PrinceOfThePoint]

Good post - this is why most homebrew kind of sucks.