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AbeLincoln 01-12-2012 09:30 PM

Fermentation temperature clarification
 
Does "fermentation temperature" refer to the temperature inside or outside of the fermentation vessel?

copyright1997 01-12-2012 09:36 PM

Quote:

Originally Posted by AbeLincoln (Post 3657758)
Does "fermentation temperature" refer to the temperature inside or outside of the fermentation vessel?

Inside.

If measuring outside, try to get as accurate of a reading as you can. For my cheapo ebay digital temperature controller, I use bubble wrap around the temperature probe which I tape to the outside of the plastic fermentation bucket. I also try to stay near the bottom of the fermentation range. For example, I set my fermentation temperature to 64-65 when using s-04 yeast.

sjbeerman 01-12-2012 09:36 PM

inside the vessel...

AbeLincoln 01-13-2012 02:19 AM

>.< Thanks

Is there an easy/cheap modification I can do to my brewing bucket to keep an eye on wort temperature?

bigljd 01-13-2012 11:50 AM

Quote:

Originally Posted by AbeLincoln (Post 3658824)
>.< Thanks

Is there an easy/cheap modification I can do to my brewing bucket to keep an eye on wort temperature?

Throw one of these on the side of your bucket,

http://www.amazon.com/Fermometer-Adhesive-Strip-Thermometer/dp/B004B4TS1S


it will get you close enough to the inside temp. Most home brew shops sell them.

Clementine 01-13-2012 12:02 PM

If you have spare stainless steel dip tube or small diameter tubing you can make a thermowell (or buy one) then drop your favorite temp probe in there to monitor what is going on. I just made mine x 2 one for a mash thermometer and one for fermenter.

Clem

broadbill 01-13-2012 12:23 PM

Quote:

Originally Posted by Clementine (Post 3659644)
If you have spare stainless steel dip tube or small diameter tubing you can make a thermowell (or buy one) then drop your favorite temp probe in there to monitor what is going on. I just made mine x 2 one for a mash thermometer and one for fermenter.

Clem

I have also found that taping a probe to the side of the fermenter and then insulating with with bubble wrap is almost if accurate (if not just as accurate). Can't blame somebody for geeking out though!

AbeLincoln 01-13-2012 05:44 PM

I've been using a stick-on liquid crystal thermometer, but I think I'm ready to begin probing the core temperature of my fermenting wort in order to achieve greater control over fermentation.

Here's my concern:

The specific heat of the high density polyethylene bucket fermenter is somewhere between 1.8 - 2.7 J/g.K (joules per grams Kelvin)* whereas the specific heat of the air in my fermenting room at 20 degrees Celsius is 1.005 J/g.K ** If the wort has a gravity of 1.05, its specific heat would be just above 4 J/g.K throughout the possible range of fermentation temperatures for my yeast (Safbrew T-58). ***

What this means is that while using the stick-on thermometer, I'm getting some measurement of the average kinetic energy between the air and bucket (which have greater thermal transfer potentials than wort [ie. lower specific heat]), and the fermenting wort.


Quote:

Originally Posted by Clementine (Post 3659644)
If you have spare stainless steel dip tube or small diameter tubing you can make a thermowell (or buy one) then drop your favorite temp probe in there to monitor what is going on. I just made mine x 2 one for a mash thermometer and one for fermenter.

Clem

I like Clem's idea because it involves measuring the average kinetic energy between two substances and not three (provided one uses a steel temperature probe). Further, steel has a relatively low specific gravity (.5 J/g.K)**** and thus a better thermal transfer potential than both plastic and air. It should essentially suck the heat right out of the surrounding wort and give one a reading with a much more negligible deviation.

The thermowell has two apparent benefits then:
  1. Greater accuracy in temperature measurement
  2. Ability to measure core temperature of wort

I suppose I could drill another hole in my lid, stick a rubber lid grommet into it, then find or make a stainless steel thermowell of the appropriate diameter and length and be all set.

Any thoughts?

Thanks guys :mug:

* Material Properties of HDPE, Commodity Polymers | Polymers Data Sheets

**Air Properties

***Sugar - Specific Heat Capacity (SG to brix calculation necessary to use calculator)

****Metals - Specific Heats


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