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Old 10-09-2013, 09:36 PM   #1
Queequeg
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Default Monitoring Fermentation temps

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.

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Old 10-09-2013, 09:53 PM   #2
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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.

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Old 10-09-2013, 09:59 PM   #3
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How about something like this.

thermowell.jpg  
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Old 10-09-2013, 10:11 PM   #4
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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.

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Old 10-09-2013, 11:38 PM   #5
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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.

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Old 10-10-2013, 01:16 AM   #6
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Quote:
Originally Posted by Queequeg View Post
[...]the temperature around and on the fermentation vessel is generally accepted as unrepresentative of the temperature of the beer inside.[...]
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.


Quote:
Originally Posted by PAjwPhilly View Post
[...]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.[...]
Let me guess: the thieved sample was cooler.

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

Cheers!
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Old 10-12-2013, 10:08 AM   #7
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Quote:
Originally Posted by day_trippr View Post
Where did you get that idea?
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.
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Old 10-12-2013, 11:24 AM   #8
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Quote:
Originally Posted by Queequeg View Post
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.
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.
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Old 10-12-2013, 11:37 AM   #9
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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

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Old 10-12-2013, 11:40 AM   #10
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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.

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