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Old 12-13-2006, 02:59 AM   #1
Sep 2006
Posts: 45

I just bought a cheap $20 48 qt coleman rectangular cooler to hopefully use for mashing and I decided to do a little test for temperature retention...

So I grabbed a thermocouple meter from work, warmed some water to around 160*F and dumped it in the cooler... First measurements in the cooler was 156.9*F, and after an hour it was 145.2*F..

Is 12*F too much of a drop for mashing? I haven't done any AG yet, and am in the gathering equipment phase...

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Old 12-13-2006, 03:05 AM   #2
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Oct 2005
Oak Grove, Oregon, USA
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12F is way too much. You need to keep the temperature within 1 or 2 F. First, you need to heat the cooler up first. So, check the temperature after about 10 minutes and at 60.

I pour boiling water in my cooler and let it sit for 10, then I drain it, toss in the grains, adjust the water temperature & add it back.
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Old 12-13-2006, 03:11 AM   #3
Sep 2006
Posts: 45

It was at 152.9 after 10 minutes, so that's still a 10 degree drop..

Guess I'll return it.. I was looking at the Coleman Extreme's, but I also ordered a normal cooler bulkhead today from Northern Brewer, and the extreme's need the XL...

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Old 12-13-2006, 03:12 AM   #4
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May 2006
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The Xtreme works great. I preheated before my last mash, the first time with the cooler - I didn't lose a single degree, even in 40 degree ambient temp. Return the bulkhead, get the XL, it fits right in perfectly.
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Old 12-13-2006, 03:16 AM   #5
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Jul 2006
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You can use just about anything that'll hold the correct amount of water/grain for a mash tun, assuming you have a means of controlling the temperature. My system is a good Igloo Ice Cube cooler with a recirculating system that will maintain and/or raise the temperature as I desire. That's probably a bit more involved than you want to get, but do a search on decoction mashing if you're having trouble maintaining temps.
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Old 12-13-2006, 10:10 PM   #6
boo boo
Jun 2005
Hearts's Delight, Newfoundland
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It would depend on how much water you dumped in the cooler and if you pre warmed it or not. Keep in mind the grain will hold a better heat than water alone.
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Old 12-14-2006, 02:53 AM   #7
Feb 2006
Posts: 211

I use a 5 gal Coleman cooler with a manifold in the bottom for a mash tun. I fill the cooler with hot tap water about a half hour before I dough in the grain. Just before doughing I dump the tap wter and dough in with water that is about 172 F. After doughing in the temp is usually 152 F. If necessary I adjust with boiling H20 or ice cubes. I stir 2 or 3 times. The temperature remains constant at 152F for an hour. .
I have never tested the the tun with just hot water to see if there is a drop in temp.

If you have an insulated Igloo cooler It should be able to maintain a constant mash temp for an hour if you have the top on tight and you don't open it too many times

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Old 12-14-2006, 03:37 AM   #8
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Jan 2006
Santa Cruz, CA.
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Also a lot of the heat seems to go out the lid. If you put a blanket or a couple of towels on the top it helps retain the heat.

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Old 12-14-2006, 04:30 AM   #9
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Aug 2005
Pasadena, CA
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I used to have a 48qt IceCube Mash Tun. Its now just a lauter tun becuase I got soo frustrated with trying to figure out its temprature adjustments.

Just thought I would give you some words of discouragment

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Old 12-14-2006, 08:47 AM   #10
Dec 2005
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Dont underestimate the importance of preheating your mash tun, not only does it improve temperature retention through out the mash period it is vital to acheiveing a stable mash temperature as quickly as possible, minimising or eliminating any hot or cold water additions.

A kettle full of near boiling water poured into the MT 10-15mins before mashing does the trick.

Don't worry too much about the large temperature drop at the moment the mash will retain the heat much better than water alone.

It's worth throwing a few blankets or a sleeping bag over the MT to help retain the temperature, it's also worth putting a folded towel under the MT to insulate the bottom from the surface below.

With these simple steps you should acheive a near zero temperature drop throughout a 90 min mash period which will give you far greater control over the resultant beer.
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