I did my first AG about two weeks ago with a rectangular cooler as my mash tun. When I preheated the mash container I could see the steam from the boiling water escaping out of the back. Slightly worried, I poured out the boiling water, added my grain and then the heated water. I stirred to ensure no air pockets and closed the lid. 20 minutes later I returned to stir again and saw that the temperature had dropped from 153 to 149. I didn't open the mash tun from that point on and hoped for the best. We'll see how it turns out in a few weeks.
The Mash Tun itself is just a rectangular cooler with the stainless steel braid as the manifold (is that the right word?). I pumped the lid full of "great stuff" (more like sucky stuff, I still have that crap on my hands) to aid in the heat retention. My question is, what other steps can I take in my mash tun construction to ensure that I keep as much heat as possible? I was thinking some kind of foam weather stripping and drilling a hole for a permanent thermometer. Thoughts? Thanks
I think it's possible you didn't get it well enough mixed in the first place and that would account for your reading. And just stop opening it to stir! Stirring is unnecessary and you lose heat every time you open the cooler.
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I am also using a rectangular cooler for a mash tun, but have not experience the temperature drop you have. The three times I've used it, the temp in my garage has been mid eighty's, so that may have something to do with it. After I dough in, and get the temp where it want it, I close the lid and place a larger blancket over the cooller, the something heavy on the lid. I have been pleased to check it after an hour, and it has only lost one degree. I did not mount a permanent thermometer because it would be a source of heat loss and with a plastic cooler, I cant just fire up the gas to bring the temp up. I would say insulate as best you can, close the lid, and dont open it until your done.
I remember my dad, when teaching me about BBQing, would say "If your lookin, you aint cookin."
IMO the best way to preheat a cooler mash tun is to add your strike water about ten to fifteen degrees over strike temp. Let is sit for 10 - 20 minutes and the cooler will heat up while the strike water drops to strike temp. Sounds like you were a bit low when you mashed in.
Most any coooler will have marginal temp loss if preheated this way
I'll echo what wilserbrewer said. Your cooler was still pulling heat when you doughed in. You either need to learn how much heat the cooler will pull and strike at that temp or go in way hot and let it cool down to your strike temp. I doubt the cooler is letting 4F out unless your ambient temp is 20F.
I doubt the cooler is letting 4F out unless your ambient temp is 20F.
Even if he can see steam coming out around the lid? I'd imagine that with a leak big enough you could see a 4*F degree loss over an hour.
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I lose about 2 degrees in an hour with no visible leaks. Preheating will help, but if steam's getting out there's an issue somewhere. I wouldn't spend any money fixing up the cooler, since Coleman Xtreme's (what I use) are so cheap; you probably spent almost half as much on the can of Great Stuff as it would have cost for a new cooler! Try preheating (it's easier for me to just add about a quart of boiling water rather than overheating my entire strike water and then waiting, but that's just how I've learned to do things). Try throwing a big old blanket on top. Leave the lid closed, just check the temp at the end of the mash to see how much you lost.
Even if he can see steam coming out around the lid? I'd imagine that with a leak big enough you could see a 4*F degree loss over an hour.
Which leads me back to my original thought of perhaps some sort of foam weather stripping around the edge to give it a better seal. I've never read anything about that but I wonder if it would work. Thoughts?
Strikes me as likely to get messy; weather stripping that's gotten covered in wort sounds like a bitch to clean. Things don't have to be perfectly sanitized (pre-boil), but I'd try something on the outside of the cooler (blanket) first.
Mash Cooler Improvement
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