I just recently moved from direct fire mashes in my kettle to doing them in a round beverage cooler, 10 gal. I am dropping 6-8 degrees F by the end of a 60 min mash. I tried pre heating the cooler, but it didn't seem to make a difference. It seems to me this should not be happening. Anyone have an idea of why this is happening and how to fix it?
Temp drop in mash cooler
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BrewinBromanite
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How full is the cooler during the mash?
Do you use any of the available calculators to help estimate strike temp, figure in the temp of the grain pre-mash, etc? Are you opening the lid and stirring throughout? If so, for how long? What ambient temp is it where you are mashing?
I use a 5 gal round cooler (pretty full typically with just enough room to comfortably stir). I pre-heat, use the calculators which seem to be pretty helpful, and never drop more than 2-3 deg over an hour. Whenever I have, it's always been when I've forgotten to preheat.
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Do you use any of the available calculators to help estimate strike temp, figure in the temp of the grain pre-mash, etc? Are you opening the lid and stirring throughout? If so, for how long? What ambient temp is it where you are mashing?
I use a 5 gal round cooler (pretty full typically with just enough room to comfortably stir). I pre-heat, use the calculators which seem to be pretty helpful, and never drop more than 2-3 deg over an hour. Whenever I have, it's always been when I've forgotten to preheat.
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BrewinBromanite
Well-Known Member
... And that one time I ran out to the gas station for ice during the mash (to be used later for chilling after the boil), and returned to the mash having dropped from 154 to 147. My brew-bro told me he had stirred 3 separate times for about 3-4 mins each time... A good stir once or twice for 10-30 sec is probably a better route. (I also do BIAB, so a little stirring seems to help with efficiency.)
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Natdavis777
Well-Known Member
I have found coolers to be the best mash tuns. My rectangular cooler never dropped more than 2 degrees over an hour. I always pre-heated for 15 min with 170F water, then stirred the remaining temp down to my strike temp (usually 164F). What type of cooler are you working with and what is your exact process?
I was having a similar problem with my 10 gallon round Rubbermaid cooler. I started putting some aluminum foil on top of the grain to help heat retention, and I also started measuring immediately after opening the lid. Doing those two things I only lose 1 or 2 degrees. Oh, and I also preheat with hot tap water, which you are already doing.
guldalian
Well-Known Member
Ok thanks for the input. Cooler is typically 1/3 full, cuz I'm doing 5 gal batches. I do not open it the entire mash. I make sure I hit strike temp before closing her up. I'll try the foil today. Also might try wrapping it in a blanket like I did my kettle.
stpug
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Coolers work well but they are definitely lossy - doesn't matter how you dice it. Since they don't heat, they slowly lose temperature. Several easy techniques can be used to minimize the lossy factor, it just comes down to what you are willing and want to do. I've implemented a few on my round cooler (5 gallon) that keep me within about ±1°F of my mash temp. Here's what I do:
-I mash in a room that is always around 70F (kitchen)
-I've insulated my cooler lid with expanding spray foam insulation (great stuff brand)
-Reserve 1 quart of my strike water for a mid-mash, temperature refresher (should be at/near boiling at midway through mash when adding)
-Preheat my strike water by 10°F; add to cooler and seal; wait 10-15 minutes to come down to desired strike temp
-After doughing in, use syran/plastic wrap over the top of cooler before cranking on the lid (acts as an airtight gasket of sorts)
I believe the last point (syran/plastic wrap) is a big one to maintaining temperature in my MLT. You can test how easily heat can be lost by performing an easy test. With a completely empty MLT, close your lid like normal; open the ball valve; now blow in the ball valve so you're blowing air into the MLT. If you can blow into the MLT then you have air leakage at the lid; if you cannot blow in the MLT then you have a good seal. If you find that you have an air leak then try the syran/plastic wrap technique. Simply lay over two strips (in a '+' sign) of plastic wrap over the top of the MLT, making sure to overlap the cooler threads; then crank on your lid again; and try the blowing test again.
The mid-mash refresher is done because coolers are lossy vessels. No matter what you do, you will always lose temperature and never gain inside a cooler when mashing. By refreshing the temperature at about the midpoint ensures that your variance will be minimal (usually 1-2°F).
Food for thought!
-I mash in a room that is always around 70F (kitchen)
-I've insulated my cooler lid with expanding spray foam insulation (great stuff brand)
-Reserve 1 quart of my strike water for a mid-mash, temperature refresher (should be at/near boiling at midway through mash when adding)
-Preheat my strike water by 10°F; add to cooler and seal; wait 10-15 minutes to come down to desired strike temp
-After doughing in, use syran/plastic wrap over the top of cooler before cranking on the lid (acts as an airtight gasket of sorts)
I believe the last point (syran/plastic wrap) is a big one to maintaining temperature in my MLT. You can test how easily heat can be lost by performing an easy test. With a completely empty MLT, close your lid like normal; open the ball valve; now blow in the ball valve so you're blowing air into the MLT. If you can blow into the MLT then you have air leakage at the lid; if you cannot blow in the MLT then you have a good seal. If you find that you have an air leak then try the syran/plastic wrap technique. Simply lay over two strips (in a '+' sign) of plastic wrap over the top of the MLT, making sure to overlap the cooler threads; then crank on your lid again; and try the blowing test again.
The mid-mash refresher is done because coolers are lossy vessels. No matter what you do, you will always lose temperature and never gain inside a cooler when mashing. By refreshing the temperature at about the midpoint ensures that your variance will be minimal (usually 1-2°F).
Food for thought!
SpeedYellow
Well-Known Member
Let's remember the big picture here. The vast majority of conversion happens in the first 15-20 minutes (in fact, I know of an area pro brewery that does 15 minute mashes). So a loss of 2F per hour is just 0.5F in the period where conversion is mostly complete. What happens after the first 15-20 minutes simply isn't that important.
Just food for thought.
Just food for thought.
vwmasstransit
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Same as stpug, I filled my lid with expandable foam and only drop 1 degree in an hour. I don't wrap it, or use syran wrap and I don't open it for that hour. I must be lucky I guess 
Question about that expanding-foam-inside-the-lid thing: does it ever actually cure all the way through?
I remember from years ago here folks that tried that and ended up with a lid full of uncured liquid...
Cheers!
I remember from years ago here folks that tried that and ended up with a lid full of uncured liquid...
Cheers!
stpug
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I did not use "great stuff" brand expanding foam and I can confirm that it did NOT cure correctly - AT ALL! I have heard reports that great stuff brand does not have the same problem as the **** I used.
To resolve my problem with no_name brand expanding foam I had to add moisture to get it to expand and cure. I used a spray bottle and would mist in some water through each of my application holes (I have about 7 or so cm-diameter holes).
If I do this again then my process would be to simply add moisture to the inside of the lid prior to application. In fact, I would probably use starsan since it has a surfactant to provide good even coverage over the entire inside of the lid (add a 1/2 cup of starsan to inside of lid; shake it around; drain out as much as I could; immediately follow with foam application). I would also use considerably less foam; it's easy to way over-apply the foam. I would also use slightly larger holes (3/4" maybe).
Easy test to see if things are cured is the squeeze test: See if you can push the top and bottom of lid layers against each other. If you can then it is not cured. If you can't then it's cured. If you find a spot that's not cured you can poke a small hole to apply some water.
vwmasstransit
Well-Known Member
I just used the cheap stuff at Lowes. Filled the crap out of it and 2 days later trimmed off the excess. And then smoothed it out with food safe silicone so it would seal on the outer edge. Gave it a neat clean look. Viola! View attachment ImageUploadedByHome Brew1432001102.139066.jpg
At some point here, you're going to have beta amylase thriving more than you might want. The higher the temps go, the more you will denature, but it's also a function of time as it's not an instant and all thing. Homebrewers commonly mash longer when they desire a more fermentable wort...and though all I have is a working knowledge and no concrete exBeerimental results or hardcore science, I believe at least some of this is accomplished / helped by temperature loss.
I agree that a 1-2 degree temperature drop over 60 minutes is probably not going to be a big deal, but the OP is talking more around a 6 degree drop. I had a GOTT-style "made for homebrewing" mash tun that lost about this much or a tad more, and it was a bear to keep almost every beer from finishing below 1.010.
Some people have even addressed problems with their beers drying out more than they've wanted by putting their first runnings on heat while they sparge. Just throwing more food onto the thought feast.
FWIW, I filled the lid of my 10g round cooler with great stuff foam and it worked like a charm to help hold the heat. I ran a 45 min mash yesterday and didn't lose even a tenth of a degree. It stayed at 158.0 the entire time (and yes I do trust my thermometer). Before adding the foam I would lose a degree or two (which still isn't bad) but this really did help! So if you're thinking about going this route, I would highly recommend it! Brew on!
Tim
Tim
oljimmy
Well-Known Member
Guldalian, this is an amazing result. It has to be due to the materials on which the tun is sitting. I'm assuming your table is hardwood or something similar, what is your floor made of/covered with?
I drilled about 8 or 9 holes on the underside of the lid toward the outer ring and then squirted in the foam. I then let it cure over night and then cut off the overflow and then sealed the holes with food safe silicone.View attachment ImageUploadedByHome Brew1433102927.977073.jpgView attachment ImageUploadedByHome Brew1433102974.908862.jpg
Wow....your serious....with injecting foam and reflectix.
guldalian
Well-Known Member
The table was just a card table I use for brewing purposes. The ground is the concrete floor of my garage. I think the temp loss was due to air currents under the tun while sitting up on the table. I also cover the grain with foil and the cooler with a blanket. Those 2 things did not work while on the table, but worked like a charm while on the ground.
I use the reflectix because I like the look!
Kidding.....on the batch I did before adding the foam, I noticed how warm the lid was, despite the reflectix. This is why I added the foam. On Saturday, I brewed and had no where near the heat on the lid like I did before adding the foam.Similar threads
