This is what internal temps do with no temp control

I pitched my wild yeast into a brown. The other half is under control with Roeselare. I wanted to see how far above ambient temp active fermentation will go, so I was willing to let this run wild.

I keep reading "3 degrees", so I thought I'd test it. This might produce a headache beverage, but we'll in a few months.

As you can see, at peak, there was almost a 5 degree difference from the ambient midpoint. The zigzag room temp is because of a heater to keep the room livable. Of course, this is for a specific volume, pitch rate, oxygenation rate, and ambient temp, but it's probably indicative of most.

Awesome it's good to see some real data once in a while. Do you think a swamp cooler would keep the internal temps under the supposed "3 degree above ambient" mark?

It is hard to predict what the temperature difference is going to be - way to many external variables. If you ferment in a closed closet, you will get very different results than if you ferment in a very open room with good air circulation. In my basement right now, my fermentors tend to run about 2 F over air temp

I assume the ferm temp reading was from a probe, so measuring the internal temp. I'd be interested to see a third line representing the temp reading on the exterior of the fermenter (typical fermometer reading). Curious what the measured difference would be between the fermometer and the actual internal temp.

Nice plot! Thanks for sharing this. A water bath will match the temperature of the fermentation within one degree in my experience. The temperature stability of 5 gallons of beer in 5 gallons of water is also very good. I'll have to look for my data logs, but I would be surprised if the fermentation temperature gets more than three degrees about air temperature in a water bath.

See here for details
http://woodlandbrew.blogspot.com/2012/12/fermentation-temperature-control.html
http://woodlandbrew.blogspot.com/2012/09/swamp-cooler.html

BGBC said:

Curious what the measured difference would be between the fermometer and the actual internal temp.

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I've plotted that before and they are almost identical. Less than a degree of difference.

Nice info, pelipen! Seems a lot of folks think the temp rises much higher than your info shows, and I'm sure given the right circumstances they may be right.

Personally, I've found it hard to buy into a 15deg increase...

hopmonster2189 said:

Awesome it's good to see some real data once in a while. Do you think a swamp cooler would keep the internal temps under the supposed "3 degree above ambient" mark?

Click to expand...

I've done a lot of graphs with swamp coolers, and yes they are very effective at controlling your temps. There is so much thermal mass in the water bath, that it's easy to keep the internal heat from running away. The churning of the wort during active fermentation equalizes temps very well. The only downside to swamp coolers is that they require more hands on, and a lot of water.

Roger that I figured they were pretty efficient. The large mass of water can be a pain sometimes, but its worth it.

WoodlandBrew said:

I've plotted that before and they are almost identical. Less than a degree of difference.

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I can confirm this with another graph.

The portion of this graph to look at is the section to the right of the veritcal line on the far right:
The light blue line is a probe attached to the side, with insulation around the outside to protect from ambient temps.

The green line is the internal temp, with the probe directly opposite the external prob maybe 1 cm from the wall. The difference is negligible. You can see the waves in the light blue line due to the glass temp changes having some influence on the reading.

For all intents and purposes, "fermometers" are only limited by their accuracy with the chemical change to produce color, and your ability to interpret.

pjj2ba said:

It is hard to predict what the temperature difference is going to be - way to many external variables. If you ferment in a closed closet, you will get very different results than if you ferment in a very open room with good air circulation. In my basement right now, my fermentors tend to run about 2 F over air temp

Click to expand...

This is true. In a small room, the heat from the fermentation will drive up the ambient, increasing the activity of the yeast, and could run to much higher ultimate temps. It would be interesting to know what the ultimate delta would be.
Even something as simple as adding a small fan to mix the air is likely to have slightly different results. I suspect that the delta also change as a function of ambient temperature, so your 2 degree difference at basement temps is easy for me to believe. There are a ton of variables.

wickman6 said:

Nice info, pelipen! Seems a lot of folks think the temp rises much higher than your info shows, and I'm sure given the right circumstances they may be right.

Personally, I've found it hard to buy into a 15deg increase...

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Every system will be slightly different. I think it would be hard to get a 15 degree difference unless the carboy was inside insulation to artificially drive it up. I'm not willing to test that

BGBC said:

I assume the ferm temp reading was from a probe, so measuring the internal temp. I'd be interested to see a third line representing the temp reading on the exterior of the fermenter (typical fermometer reading). Curious what the measured difference would be between the fermometer and the actual internal temp.

Click to expand...

Yes, I have a stainless probe in the center of the beer, and one several inches away on the outside at about the midpoint of the beer level. "Ambient" is difficult to define. I decided to stay close to the carboy since it will impact its surroundings, and the difference between floor to ceiling is probably 10 degrees or more this time of year.

Do you have a link to your testing setup? Would love something like this for my fermentation chamber and/or keezer.

WoodlandBrew said:

Nice plot! Thanks for sharing this. A water bath will match the temperature of the fermentation within one degree in my experience. The temperature stability of 5 gallons of beer in 5 gallons of water is also very good. I'll have to look for my data logs, but I would be surprised if the fermentation temperature gets more than three degrees about air temperature in a water bath.

See here for details
http://woodlandbrew.blogspot.com/2012/12/fermentation-temperature-control.html
http://woodlandbrew.blogspot.com/2012/09/swamp-cooler.html

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Nice charts. I'm going to have to kill some time reading through your site. I love data.

I prefer water baths personally. I switched to a cylindrical beverage cooler recently, because I got it for super cheap, and there is so little dead space that the temperature control is tight.
In a water bath... you can maintain a flat line. I had a tiny pump recirculating water around the carboy, and would feed in ice water as needed with the johnson A419 kicking on another water pump in a cooler. It worked awesome, but was klunky and I got tired of freezing water bottles. I was going to buy a fridge to chill the water, but then I found this cylindrical cooler for $30 and it was a no-brainer.

thadius856 said:

Do you have a link to your testing setup? Would love something like this for my fermentation chamber and/or keezer.

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This is what I'm using (I tried to avoid endorsing any one place and link to main sites where possible):
Dallas/Maxim DS18B20 sensors, available from a number of sources, even pre-wired and waterproof.
A DS9490R 1-wire USB adapter
I made probes out of this stainless conduit. Seal it up with something food grade. Lots of epoxy or FDA/NSF rated sealant options exist. you could also just stick a wired probe into a thermowell a lot of brew stores sell, like this one.

I run linux, so I scan the probes using Digitemp. owfs is another approach
I insert the data into a round robin database called RRDTool, which also does the charting. I do charting with php scripts which also build a web page to update once a minute. I only log once per minute.

My plan is to move all this to a Raspberry Pi later and probably use GPIO instead of the 1-wire USB controller.