It just occurred to me that my fermometers are only reading the temperature of the outside of the liquid. Should I be adjusting that temp +/- degrees?
Yes, by 5 degrees on average during primary. After that, what you read will be close to temp. at least good enough.
I have a primary that just took off now, my strip says 59, that to me means mid to low 60’s.
I try to keep the beer on the low side of fermentation just because i know it will have a warmer inside temp. Most likely it will be higher than what the strips will indicate. I use this to my avantage to make a good brew. Low and Slow wins the race.
I mostly agree with the above, but think it is closer to 2 degrees than 5. The liquid inside is constantly churning during the peak, so I think the outside temp is pretty close. I am in the slow and steady camp too and most ales have an ambient temp if 58 or 59 degrees. I show a 4-5 degree rise on the fermometer
I think the temp you get of a fermometer is close enough to call it the real temp. I know Jamil tapes a temp controller probe to the outside of this fermentors, and calls that the temp of his beer. If it good enough for one of the most awarded homebrewers of all time, it’s good enough for me.
I’m mostly curious because a black ale I made tasted a little sour appley… I’ve been much better about temp controls than I have been in the past, but I know that flavor can be attributed to acetaldehydes. This was one of the only things I could think of that could have gone wrong.
What really worries me is that I’m treating two other five gallon beers (fermenting as I type) the same way I treated this ale with maybe 2-3 degrees difference. So, given the flavor of this ale I’m started to get the itch of opposing Charlie (i.e. Stress-out-worry-have-a-home-whisky).
I’m mostly curious because a black ale I made tasted a little sour appley… I’ve been much better about temp controls than I have been in the past, but I know that flavor can be attributed to the ever temperature temperamental acetaldehydes. This was one of the only things I could think of that could have gone wrong.
What really worries me is that I’m treating two other five gallon beers (fermenting as I type) the same way I treated this ale with maybe 2-3 degrees difference. So, given the flavor of this ale I’m started to get the itch of opposing Charlie (i.e. Stress-out-worry-have-a-home-whisky).
I’ve always considered the fermometer temperature to be “close enough” to the actual beer temperature. The wall of your fermenter is going to have a higher thermal conductivity than the air, so the temperature of the liquid should dominate the result.
[quote=“Hoppenheimer”]I’m mostly curious because a black ale I made tasted a little sour appley… I’ve been much better about temp controls than I have been in the past, but I know that flavor can be attributed to the ever temperature temperamental acetaldehydes. This was one of the only things I could think of that could have gone wrong.
What really worries me is that I’m treating two other five gallon beers (fermenting as I type) the same way I treated this ale with maybe 2-3 degrees difference. So, given the flavor of this ale I’m started to get the itch of opposing Charlie (i.e. Stress-out-worry-have-a-home-whisky).[/quote]
Green apple flavor is usually the result of not enough time on the yeast. Listen to Charlie. Relax, Don’t Worry, and let your beer ferment longer while you Have a Home Brew.
I don’t see how the temp could be anything but evenly distributed, or very close to it, since the beer is constantly churning throughout active fermentation. I guess I could see a 1 - 2 degree difference between the middle and the edges of the carboy, but 5 degrees? I’d be surprised.
[quote=“Nate42”][quote=“Hoppenheimer”]I’m mostly curious because a black ale I made tasted a little sour appley… I’ve been much better about temp controls than I have been in the past, but I know that flavor can be attributed to the ever temperature temperamental acetaldehydes. This was one of the only things I could think of that could have gone wrong.
What really worries me is that I’m treating two other five gallon beers (fermenting as I type) the same way I treated this ale with maybe 2-3 degrees difference. So, given the flavor of this ale I’m started to get the itch of opposing Charlie (i.e. Stress-out-worry-have-a-home-whisky).[/quote]
Green apple flavor is usually the result of not enough time on the yeast. Listen to Charlie. Relax, Don’t Worry, and let your beer ferment longer while you Have a Home Brew.[/quote]
From what I was reading in “Yeast” a temperature variation from 65F to 75F caused an increase of acetaldehydes by 140 ppm. I guess they get eaten up by the yeasties again, but it just seemed to warrant concern about temp controls.
[quote=“Hoppenheimer”]
From what I was reading in “Yeast” a temperature variation from 65F to 75F caused an increase of acetaldehydes by 140 ppm. I guess they get eaten up by the yeasties again, but it just seemed to warrant concern about temp controls.[/quote]
I don’t think anyone here disputes that!
Well now lets see, I have a beer going thats 3 days in the primary, let me go check with my new toy, a thermopen. Hmmm, 60 on the strip and 63 on the pen. I had some high krausen and I only went as deep as the probe, about 4in. Not sure how far into the wort it went but I wanted to seal it up right away. In any case, I doubt that the middle would be 5 deg warmer than the strip, 3.5 maybe. At least not at that low ferm. temp.
However I think that a warmer ferment will mean a bigger gap in the temp reading. Lets say you fermented at 70, then i think the inside will be at least 4 to 5 deg. higher than the strip.
In any case the beer was 3 deg. higher than the strip and I stand corrected. I have always thought that the strips were inacurate but they are closer than what i thought. I’m going to check this out further on future beers and see what i get. I hope that some of you brewers will do the same and we’ll see what we come up with. Heck, it’s about making good beer right? That couple of degrees could make a difference.
Cheers and Beers my brew brotha’s. Sisters too.
[quote=“wallybeer”]Well now lets see, I have a beer going thats 3 days in the primary, let me go check with my new toy, a thermopen. Hmmm, 60 on the strip and 63 on the pen. I had some high krausen and I only went as deep as the probe, about 4in. Not sure how far into the wort it went but I wanted to seal it up right away. In any case, I doubt that the middle would be 5 deg warmer than the strip, 3.5 maybe. At least not at that low ferm. temp.
However I think that a warmer ferment will mean a bigger gap in the temp reading. Lets say you fermented at 70, then i think the inside will be at least 4 to 5 deg. higher than the strip.
In any case the beer was 3 deg. higher than the strip and I stand corrected. I have always thought that the strips were inacurate but they are closer than what i thought. I’m going to check this out further on future beers and see what i get. I hope that some of you brewers will do the same and we’ll see what we come up with. Heck, it’s about making good beer right? That couple of degrees could make a difference.
Cheers and Beers my brew brotha’s. Sisters too.[/quote]
Is that the difference between the temp of the middle of the carboy and the strip on the outside, or a measure of how accurate your fermometer is at reading temps period? I’ve never used a thermo pen before, but you could use it to measure the temp of the outside of the carboy, and compare that to the inside reading. Use the same tool to get temps to compare.
Assuming both temps are correct, there would be some wort at 63°F in the center of the carboy, and some wort at the edges at 60°F. So there’s a gradient there. The only way you could figure out the average temp of all the wort would be to shake that sucker up a bunch to homogenize it, then take a reading.
Try it and get back to us 
When someone says to ferment at x temperature, are they talking about the temp at the edge of the carboy, middle, or the average temp?
^^^ my thermowell versus the fermometer on the same carboy was about this.
i agree with the churning keeping things well mixed.
[quote=“WiVikesFan”][quote=“wallybeer”]Well now lets see, I have a beer going thats 3 days in the primary, let me go check with my new toy, a thermopen. Hmmm, 60 on the strip and 63 on the pen. I had some high krausen and I only went as deep as the probe, about 4in. Not sure how far into the wort it went but I wanted to seal it up right away. In any case, I doubt that the middle would be 5 deg warmer than the strip, 3.5 maybe. At least not at that low ferm. temp.
However I think that a warmer ferment will mean a bigger gap in the temp reading. Lets say you fermented at 70, then i think the inside will be at least 4 to 5 deg. higher than the strip.
In any case the beer was 3 deg. higher than the strip and I stand corrected. I have always thought that the strips were inacurate but they are closer than what i thought. I’m going to check this out further on future beers and see what i get. I hope that some of you brewers will do the same and we’ll see what we come up with. Heck, it’s about making good beer right? That couple of degrees could make a difference.
Cheers and Beers my brew brotha’s. Sisters too.[/quote]
Is that the difference between the temp of the middle of the carboy and the strip on the outside, or a measure of how accurate your fermometer is at reading temps period? I’ve never used a thermo pen before, but you could use it to measure the temp of the outside of the carboy, and compare that to the inside reading. Use the same tool to get temps to compare.
Assuming both temps are correct, there would be some wort at 63°F in the center of the carboy, and some wort at the edges at 60°F. So there’s a gradient there. The only way you could figure out the average temp of all the wort would be to shake that sucker up a bunch to homogenize it, then take a reading.
Try it and get back to us
When someone says to ferment at x temperature, are they talking about the temp at the edge of the carboy, middle, or the average temp?[/quote]
I could do that but my ambient temp was 60 and so was the strip, When i opened the pen it read 60 as well so there is no need to do so. When I took a reading I took the lid off, put the pen in and got 63, all this took 4 or 5 seconds, I then re-sealed.
I do understand what your trying to get at, and I'm trying to figure this out as well.
and after taking the readings earlier, i would like to check this out further.
At least I know that there is a difference, as much as I thought? No. Was there a difference? Yes, there was. Now were talking a difference of a couple degrees. Something that I'll Check out very soon and I hope that you can do the same.
With that said, It's all about making the best beer that we can. WE, as homebrewers try our best to help other homebrewers out, even to a fault.
Did anyone actually take any readings like I did or is just guessing?Going the opposite direction…
If you have a thermal well in the middle of the fermenter, the center of the beer will be a different temp than the outside area of the beer.
The only way to have a consistent temp throughout would be to have cooling lines running through the fermenter. Something that a commercial conical doesn’t have.
Pick a temp and a way you can measure it. Find the temp that make a beer that you enjoy. Enjoy it. 
I am not sure it is guessing when you have several fermenters at different stages (1 day, 1 week, 2 weeks) in the same ambient environment which is carefully controlled and you observe the changes during the process. My ambient is never higher than 60* and during the most intense part of fermentation my fermometer will rise to 63* maximum. If the beer temp at the middle of the bucket is 1-2* higher, what am I going to do? I do generally swirl after 4-5 days and do not see a rise at all.
I thought I would call everyone’s attention to the “Accuracy” information provided on the manufacturer’s website: http://tkachenterprises.com/Products.html
[quote]People have often inquired about the accuracy of the fermometer and what it is measuring when placed on the outside of the fermenter in contact with ambient air. To answer those questions, I conducted an experiment where I put warm water in a glass carboy and placed the entire setup outside in thirty degree weather and compared the fermometer to internal temperatures measured by an immersion fermometer as they came into equilibrium.
What I learned is that for every ten degree difference in temperature between the atmosphere and the fluid in the fermenter, the temperature was off by approximately one degree as follow.
0-10 degrees difference between ambient and internal temperature ~ 1 degree difference between fermometer and immersion thermometer
10-20 degrees difference between ambient and internal temperature ~ 2 degree difference between fermometer and immersion thermometer
20-30 degrees difference between ambient and internal temperature ~ 3 degree difference between fermometer and immersion thermometer
So in most normal fermentation situations, the fermometer is only off by about 0.0 - 0.5 degrees from the internal fermenting temperature.[/quote]
[quote=“wallybeer”][quote=“WiVikesFan”][quote=“wallybeer”]Well now lets see, I have a beer going thats 3 days in the primary, let me go check with my new toy, a thermopen. Hmmm, 60 on the strip and 63 on the pen. I had some high krausen and I only went as deep as the probe, about 4in. Not sure how far into the wort it went but I wanted to seal it up right away. In any case, I doubt that the middle would be 5 deg warmer than the strip, 3.5 maybe. At least not at that low ferm. temp.
However I think that a warmer ferment will mean a bigger gap in the temp reading. Lets say you fermented at 70, then i think the inside will be at least 4 to 5 deg. higher than the strip.
In any case the beer was 3 deg. higher than the strip and I stand corrected. I have always thought that the strips were inacurate but they are closer than what i thought. I’m going to check this out further on future beers and see what i get. I hope that some of you brewers will do the same and we’ll see what we come up with. Heck, it’s about making good beer right? That couple of degrees could make a difference.
Cheers and Beers my brew brotha’s. Sisters too.[/quote]
Is that the difference between the temp of the middle of the carboy and the strip on the outside, or a measure of how accurate your fermometer is at reading temps period? I’ve never used a thermo pen before, but you could use it to measure the temp of the outside of the carboy, and compare that to the inside reading. Use the same tool to get temps to compare.
Assuming both temps are correct, there would be some wort at 63°F in the center of the carboy, and some wort at the edges at 60°F. So there’s a gradient there. The only way you could figure out the average temp of all the wort would be to shake that sucker up a bunch to homogenize it, then take a reading.
Try it and get back to us
When someone says to ferment at x temperature, are they talking about the temp at the edge of the carboy, middle, or the average temp?[/quote]
I could do that but my ambient temp was 60 and so was the strip, When i opened the pen it read 60 as well so there is no need to do so. When I took a reading I took the lid off, put the pen in and got 63, all this took 4 or 5 seconds, I then re-sealed.
I do understand what your trying to get at, and I'm trying to figure this out as well.
and after taking the readings earlier, i would like to check this out further.
At least I know that there is a difference, as much as I thought? No. Was there a difference? Yes, there was. Now were talking a difference of a couple degrees. Something that I'll Check out very soon and I hope that you can do the same.
With that said, It's all about making the best beer that we can. WE, as homebrewers try our best to help other homebrewers out, even to a fault.
Did anyone actually take any readings like I did or is just guessing?[/quote]
I think you missed my point. You saw a difference of 3° from the middle of the fermentor to the edges. That means that not all the beer in the carboy is the same temperature. Some of it is fermenting at 63°F at some of it is fermenting at 60°F (I would guess the beer in between the edge and center is a steady gradient between the two). So it is really just a matter of deciding which temp reading you want to go with. Either way some of your beer is either fermenting warmer than your set point, or cooler than your set point. The important thing is to pick one of the temp readings, stick with it, and adjust your fermentation temperature to get the flavor you want.
Of course you could just get a big honkin stir plate and stir during fermentation so the temp is even throughout.
Re: fermometer accuracy, I just discovered how true it is that they are quite accurate. I recently acquired a new thermometer with a traceable NIST certification, and I used it to check the temp of some cooled wort on Sunday. The fermometer said 58*, while the certified thermometer said 58.6.
