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Old 06-09-2009, 10:29 PM   #1
bjzelectric's Avatar
Feb 2009
Hillsborough, North Carolina
Posts: 202
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First AG batch is finished and I ended up losing 6 or 7 degrees in an hour mash. I wasnt expecting this much of a loss seeing that my MLT is a cooler. Is this typical? Will this have any negative effects on my final product?
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Old 06-09-2009, 10:35 PM   #2
Jun 2009
McKinney, Texas
Posts: 91

While I've only got a handful of brews under my belt, I had the same problem when I first started. All I did to fix this was set the MLT cooler on top of a chair (or milk crate) to get it off the ground. I wish I could offer more as far as the logistics and science behind this, but all I really know is it has to do with the heat distribution from the cooler to the ground. Getting it up off the floor helps eliminate this. Hope this helps/works for you.

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Old 06-09-2009, 10:40 PM   #3
ifishsum's Avatar
Aug 2008
Portland OR
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Did you preheat it first with hot tap water? That makes a huge difference. It also will lose heat more rapidly if it's less than 2/3 full.
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Old 06-09-2009, 10:44 PM   #4
Evets's Avatar
Jan 2006
Lancaster County, Pa.
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Try this. It's a piece of 2 inch foam insulation. My last mash lost 3 tenths in one hour.

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Old 06-09-2009, 10:45 PM   #5
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Apr 2007
Oakland, CA
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As stated, pre-heating helps vastly, and if you are setting it on the concrete it will suck out some of the heat, so keep it off the ground.

Also, how often did you open it? I generally only do 1-2 stirs during my entire mash...I don't want to lose too much heat and the last two runs I had 92% efficiency.

You can also wrap it in towels and stick a pillow on top of it. More insulation is never a bad thing.

Lastly, be sure your temp was correct to begin with. Use an accurate mash calculator like Green Bay Rackers--Mash Calculators so you get it right the first time and don't have to mess with it.

Throw your thermometer in and give it time to sit at least 10 minutes for the heat to distribute before you check, or you will get an inaccurate reading. Then you'll see what the actual temp of the mash is. You may find that it didn't drop that much after all.

In any case, don't worry about it. I've never had a bad beer from mashing too low. What was your starting and finishing temp for your mash, anyway?
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Old 06-09-2009, 10:45 PM   #6
ChshreCat's Avatar
Aug 2008
Camano Island, Washington
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That... is... awesome.

I was trying to think of something like that the other day, but I only got as far as a few layers of tin foil on the surface of the grain before putting the lid on.
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Old 06-10-2009, 03:11 AM   #7
JMSetzler's Avatar
Dec 2008
Hickory, North Carolina
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Originally Posted by Evets View Post
Try this. It's a piece of 2 inch foam insulation. My last mash lost 3 tenths in one hour.
That is pretty slick. I'm getting ready to try my first AG brew soon with a newly fabricated MLT. Now that I have seen this, I'm gonna have to go look around and see where I might find a piece of foam large enough to work with my cooler.... That would solve any dead space issues that might come up due to the size of the mash vs the size of the cooler.... great post...

PS- what type of foam is that? Is it styrofoam or some sort of foam rubber?
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Old 06-10-2009, 04:03 AM   #8
Jan 2009
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1st ag batch left MLT sittin on the floor all alone and lost 6 deg in one hour. since then weve been sitting it on a pillow and wrapping it with a sleeping bag and havent lost more than one degree. We pre-heat with almost but not quite boiling water for 15-20 minutes.

1st ag batch (Bee Cave Haus pale ale) tasted amazing anyway
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Old 06-10-2009, 05:26 AM   #9
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May 2009
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Pretty slick Evets:
Cudos on the foam cap. I have been planning to do that soon as well as I lose about 5 degrees in an hour. I tried keeping it off the ground, but it is way obvious the problem is the lid as I can feel how warm the lid is during the mash. If the top of the lid is warm, it is letting out heat. It's either underinsulated, or not insulated at all.

I am a bit worried about what most foam might leach under heat, so was going to go with standard styrofoam like cut the bottom off a disposable cooler. What did you use?
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Old 06-10-2009, 05:36 AM   #10
Dec 2008
Yankee Hill, CA
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Another idea floating around here is to drill some holes in the lid of your MLT and squirt some great stuff in there. Considering of course, that your lid is hollow.

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