Monitoring Fermentation temps

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Queequeg

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I keep reading that the biggest improvement you can make to your home brew is consitent and well controlled temperature during fermentation.

How exactly do you achieve this? Cooling and warming systems aside, the temperature around and on the fermentation vessel is generally accepted as unrepresentative of the temperature of the beer inside.

It would seem the average homebrewer know sthe solution may actually be warmer but by how much, all I seem to find is fairly wild estimates. Does anybody have any sort of system for more accurately estimating the temperature in the middle of the bucket? Either low or hi tech, suprise me.
 
The sticky "fermometer"-style liquid crystal strips are actually pretty accurate, at least if you're doing manual temperature control. You can calibrate it by also measuring the temperature of the water with a calibrated thermometer and seeing if it reads a little high or low. In air, it'll be within a degree of the beer in the middle of the fermentor, and in a cooling/warming water bath, it'll be about half-way between the temperature of the beer and the temperature of the bath, so, you can infer the temperature of the beer if you've also got a floating thermometer in the bath.

I'm still dreaming of the day I get an automatic system together, but, I've heard very few complaints about the method of sticking the probe to the side of the fermentor then insulating it from air temperature swings with styrofoam or something.

You can also build a thermo-well to get readings from inside the fermentor, if you're handy and have time on your hands.
 
How about something like this.

thermowell.jpg
 
I now use an stc1000 with a stand up freezer and a brew belt. I tape the probe to the side of the bucket insulated by some bubble wrap. I have use a thermowell but it seemed to cause the hot and cold to cycle a lot more. That and the probe on the side seems to get the average temp just fine.
 
I have been trying to perfect my fermentation temps recently.

To test the inside of the fermentor. Take a sample with a thief and test it. I have seen the difference between the fermometer (stick on thermometer) and the inside of my carboy up to +5°F. And that was in an 1.094 beer at high krausen with no temp control. Using simple temp control methods I usually see about +1°F.

The two methods, outside of buying major equipment, that I found are the wet T-shirt and fan method and the water bath method. They both are pretty simple. The water bath is easier, just add ice to the bath and measure your bath temp. Try to keep the bath temp at your intended temperature. The wet T-shirt and fan is a good way to drop the temps by a few degrees... But you have to keep the T-shirt wet.
 
Queequeg said:
[...]the temperature around and on the fermentation vessel is generally accepted as unrepresentative of the temperature of the beer inside.[...]
Click to expand...

Where did you get that idea?

I've used an accurate digital thermometer in a thermowell versus an LC stick-on versus a probe strapped and insulated to the outside of a glass carboy - all at the same time - and all three were within a half degree F of each other.


PAjwPhilly said:
[...]Take a sample with a thief and test it. I have seen the difference between the fermometer (stick on thermometer) and the inside of my carboy up to +5°F.[...]
Click to expand...

Let me guess: the thieved sample was cooler.

That's certainly not a reliable way to compare wort temperature readings...

Cheers!
 
Queequeg said:
I keep reading the action of fermentation increases the temp inside the vessel. Some say by 5 degrees F. This is quite a significant difference.
Click to expand...

The activity of the fermentation does increase the temperature of the beer but since the beer is in contact with the vessel it is fermented in, that vessel will be pretty close in temperature with the beer inside it. Half a degree difference is what has been tested. If you put that vessel into a tub of cool water, that water will absorb the heat created by the fermentation pretty effectively so by keeping the water cool, you keep the fermenting beer cool.

The temperature rise from fermentation depends on how active the yeast are so when you ferment a little warm, the beer can warm quite a bit but when you start the fermentation process near the bottom end of the yeast's preferred range, they aren't as active so they won't raise the temperature by nearly as much. I start mine at ~62 F. and keep them in a room that stays that temperature and the highest temperature I have seen for the fermenter is 64 because the yeast just don't have a chance to get active enough to warm it any more. If I included a water bath I could probably keep the beer at 62.
 
my last brew I put the temp probe wire thru the grommet with my airlock and the internal temp tracked fairly close to the stick-on thermometer on the side. used cold water bath for temp control & swapped out frozen milk jugs. internal/stick-on temps never rose above 67° and twice dropped below 60°

my best batch so far. out of 11 brewed in a year
 
Pick up a old fridge and put a temp controller on it. I strapped the probe on the side of the bucket with a bungee cord and used bubble wrap to insulate it,like the guy above. Works really well and you can get a fridge off of craigslist for cheap. Even those little dorm units will work.
 
A temperature controller, and some insulation over the probe, strapped to the carboy, my temperatures stay within 1 degree of what I set.

The probe set this way measures the actual fermentation temperture as RM-MN stated above.

001.jpg


IMG_0953.jpg
 
Queequeg said:
I keep reading the action of fermentation increases the temp inside the vessel. Some say by 5 degrees F. This is quite a significant difference.
Click to expand...

Left on its own you could indeed see the wort temperature rise by 5°F or more. But if you observe the wort it is constantly in motion, both by the CO2 evolution and thermal effects.

So the statement that you could see a 5°F difference between an accurate and properly thermowelled probe versus an accurate and properly attached external thermometer is observably unlikely...

Cheers!
 
RM-MN said:
The activity of the fermentation does increase the temperature of the beer but since the beer is in contact with the vessel it is fermented in, that vessel will be pretty close in temperature with the beer inside it. Half a degree difference is what has been tested. If you put that vessel into a tub of cool water, that water will absorb the heat created by the fermentation pretty effectively so by keeping the water cool, you keep the fermenting beer cool.

The temperature rise from fermentation depends on how active the yeast are so when you ferment a little warm, the beer can warm quite a bit but when you start the fermentation process near the bottom end of the yeast's preferred range, they aren't as active so they won't raise the temperature by nearly as much. I start mine at ~62 F. and keep them in a room that stays that temperature and the highest temperature I have seen for the fermenter is 64 because the yeast just don't have a chance to get active enough to warm it any more. If I included a water bath I could probably keep the beer at 62.
Click to expand...

Thanks for the informative post. Someone needs to make a homebrew mythbuster thread.
 
day_trippr said:
Let me guess: the thieved sample was cooler.

That's certainly not a reliable way to compare wort temperature readings...
Click to expand...

No the thieved sample was warmer... its from the "core" of the carboy... why would that be cooler?
 
Not a great picture, but hidden under there are two carboys during active fermentation in a water bath. The thermometer on the right is measuring bath temperature. The thermometer on the left is a long stem compost type thermometer with the probe in the center of the fermenting wort. For all practical purposes the reading is the same.

121783d1368448249-thermometer-measuring-fermentation-temps-mashtemp.jpg
 
the stick on thermometers are fine. the deal with homebrewing is that you learn your own system and the results it gives you. imagine that instead of numbers, each number on your stick on thermometer was represented instead by an arbitrary characters such as % ( ~ # $ etc. you would learn that when the beer is fermenting at #, you get a clean hop profile, when it is fermenting at $ you get more fruity flavors from the yeast.

my point is it isn't necessary to know the exact temperature of the center of the wort. it is more necessary to know how the parameters that YOU SET affect the beer that you craft.
 
progmac said:
My point is it isn't necessary to know the exact temperature of the center of the wort. it is more necessary to know how the parameters that YOU SET affect the beer that you craft.
Click to expand...
During active fermentation there is enough movement in the wort so that the center and parameter will be the same temperature. As activity slows so does the exothermic reaction, so even then the two still remain equal.

I only did the test above a few times and found it wasn't worth putting the probe in the wort. The bath temperature was always a very accurate representation of the wort temperature.
 
+1 to the STC-1000 temp controller. I've built 4 now for $30 a piece (if you already have your own spare power cable). I have mine strapped to a keg / carboy with bungee cords just like Rustym has his in the pictures above. I just use a washcloth folded over a couple times as the insulator rather than foam. This set up allows me to perfectly control my fermenting / lagering / serving temps within 1 degree.

But of course, the chest freezer or upright fridge is sold separately! :)
 
AnOldUR said:
Not a great picture, but hidden under there are two carboys during active fermentation in a water bath. The thermometer on the right is measuring bath temperature. The thermometer on the left is a long stem compost type thermometer with the probe in the center of the fermenting wort. For all practical purposes the reading is the same.

121783d1368448249-thermometer-measuring-fermentation-temps-mashtemp.jpg
Click to expand...

Good stuff.

I have gone for a waterbath setup for actual control. I have a larder which is about 10-16C during the autumn/winter, the idea on my next batch is the put the fermenter in the water bath with an aquarium heater and stick the whole lot in the larder.

For the water bath I just bought a 72L rubble bucket.
 
I do something like this, but well eventually upgrade to a thermowell. I use heat so brew primarly in the fall, winter and spring

IMAG2397.jpg
 

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