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Old 03-18-2012, 01:25 AM   #1
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Default Correct Mash Tun Specific Heat for 10 gal Cooler?

I, like many, use a 10 gallon Rubbermaid cooler as a mash tun. I've found that the strike water temps generated by BeerSmith are always too high. After poking around I discovered the value for "Mash Tun Specific Heat" is 0.30 and that this means the software is assuming I lose heat more quickly than I actually do. I've googled and searched this forum and cannot find a simple answer to this question:

What is the proper Mash Tun Specific Heat to enter in BeerSmith 2.0 for a 10 Gal cooler?


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Old 03-19-2012, 08:27 PM   #2
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Really...no one has figured this out?


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Old 03-21-2012, 05:32 PM   #3
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Really...no one has figured this out?
I'd love to know a specific answer to this as well, but so far haven't found it on Brad's site or this one...or anywhere else for that matter. I did weigh my cooler with the FB and bulkhead/ball valve sans lid so at least I have that entry updated, but I'm still using the default .3 for the specific heat.

I do plug in the starting MLT and grain temps and all that, but I usually miss my desired mash temp by a couple/few degrees. I've learned to hold back a gallon of strike water so I can sub some cooler or hotter water near the end of mashing in to bring it into spec...

Cheers!
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Old 03-21-2012, 08:04 PM   #4
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Not sure if this will help or not, but what I do is pre-heat my 10 gallon cooler with one gallon of boiling water and close lid. I let that sit in there for a little while (20 minutes) and then I add my strike water minus the gallon already in there and then add my grains adjusting temp like normal. I then set my Thermal mass to zero on my software and all my figures seem to come out pretty damn spot on. Hope this makes sense.
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Old 03-22-2012, 01:07 AM   #5
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Not sure if this will help or not, but what I do is pre-heat my 10 gallon cooler with one gallon of boiling water and close lid. I let that sit in there for a little while (20 minutes) and then I add my strike water minus the gallon already in there and then add my grains adjusting temp like normal. I then set my Thermal mass to zero on my software and all my figures seem to come out pretty damn spot on. Hope this makes sense.
Well, of course it makes sense - you've totally taken the heat lost in warming up the tun out of the equation

But that also totally misses the point. With the right inputs, BS should be able to tell you the precise temperature to use for the strike water that will account for all of the pertinent criteria, including heat lost to bringing the tun up to temperature. Which was the point of the thread...

Cheers!
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Old 03-22-2012, 07:18 AM   #6
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OK, I asked my neighbor, who uses Beer Alchemy, what he uses and he said that he inputs 2 lbs 3 oz and his numbers are dead on. He uses a 10 Gallon Rubbermaid cooler.
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Old 03-22-2012, 10:26 AM   #7
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Can't you just figure it out yourself in BS? By that, I mean use the temps you measured on your last batch (where the numbers were off) and adjust the TM value accordingly to hit the measured strike temp. I am able to do that in Beer Alchemy, but prefer the preheat method now as I find it more reliable. Also, I think that it is fair to say that every cooler is slightly different and one value may not work flawlessly for everyone, so a little tweaking is necessary for your system.
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Old 03-22-2012, 07:21 PM   #8
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Originally Posted by day_trippr View Post
Well, of course it makes sense - you've totally taken the heat lost in warming up the tun out of the equation

But that also totally misses the point. With the right inputs, BS should be able to tell you the precise temperature to use for the strike water that will account for all of the pertinent criteria, including heat lost to bringing the tun up to temperature. Which was the point of the thread...

Cheers!
Yeah...I do use the pre-heat method but it's not the answer to my question. I'm also having problems with BS generating incorrect temps for infusions. My mash-out was supposed to be at 168F but using the numbers generated by the program I ended up at 160F. I wonder what accounts for that error.

I'm a bit surprised that no one has the answer to my first question. There are so many math-orientated people around here that I thought for sure one of them could throw me this bone.
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Old 03-22-2012, 07:28 PM   #9
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Can't you just figure it out yourself in BS? By that, I mean use the temps you measured on your last batch (where the numbers were off) and adjust the TM value accordingly to hit the measured strike temp. I am able to do that in Beer Alchemy, but prefer the preheat method now as I find it more reliable. Also, I think that it is fair to say that every cooler is slightly different and one value may not work flawlessly for everyone, so a little tweaking is necessary for your system.
Actually, it occurs to me that there is no one number to use. Different amounts of water and grain will stack up against the cooler's heat syncing ability in differing proportions. Preheating has always seemed to be the best solution.
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Old 03-22-2012, 08:30 PM   #10
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That's exactly why I preheat to the strike temp calculated when I enter 0 for my MLT T/M value in beer alchemy.


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