Author Topic: Mash temps?  (Read 1285 times)

Offline surfin_mikeg

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Mash temps?
« on: June 02, 2011, 11:21:18 PM »
Greetings all,

As I moved from ice chest to an 8 gal insulated stainless steel pot (i.e., wrapped with wood), I'm tracking the mash temp a bit more closely and am realizing that there's a heat separation happening about 20 minutes in.  What I mean is that the heat is rising to the top of the mash and I don't have an even temperature through the depth of the grain-bed.  Does it matter?  What I'm wondering is there is any guidance for if or how often to stir the mash to even out the temp, as well as if y'all have any suggestions when heating in order to not go over a desired temp.  I'm looking to predictably go after a drier style, say a lager or saison.

Cheers! 

Offline tschmidlin

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Re: Mash temps?
« Reply #1 on: June 02, 2011, 11:44:56 PM »
Trust physics.  Mix and measure your water temp, know your grain temp.  Calculate your strike temp and trust it.  Leave the top on the cooler for the hour, cover the lid with a towel and keep it off of the floor.  It will work great.
Tom Schmidlin

Offline tygo

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Re: Mash temps?
« Reply #2 on: June 03, 2011, 03:17:59 AM »
You could stir it halfway through to make sure the heat is better distributed and to help loosen up the mash.  The downside to that is you're going to lose some heat and drop your mash temp a couple of degrees.
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Offline bluesman

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Re: Mash temps?
« Reply #3 on: June 03, 2011, 04:42:32 AM »
There may be more heat loss form the top/bottom if it's not isulated in those areas. Assuming the ambient temp is the same all around the tun and the tun is uniformly insulated all around including the top/bottom, there will be a greater heat loss across the largest surface area which is probably the outside diameter. Also keep in mind that heat rises.
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Offline hopfenundmalz

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Re: Mash temps?
« Reply #4 on: June 03, 2011, 05:46:23 AM »
You said wrapped in wood.  To me that means the bottom is not insulated.  So you could be losing a large amount of heat by conduction out the bottom.  If the bottom is insulated too, ignore this.

If the bottom is not insulated, you could always add heat by the heat source of your choice.  Stir while doing this if you do not have a false bottom.  If you have a ball valve on the pot, you can then also recirculate some of the heated liquid to the top and stir.  That will help get the temps even.
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Offline surfin_mikeg

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Re: Mash temps?
« Reply #5 on: June 03, 2011, 08:44:12 AM »
Indeed, it is not insulated on the bottom, I have it sitting on top of a burner.  I do get heat loss from the equipment, was much worse before I wrapped it, 1 degree per 5-7 minutes.

How I got here was that I add about 1/4 - 1/2 gallon of water to my grains before crushing and let it sit for an hour (the crush turns out quite differently as grains are more squished than crushed, I like it), but failed to account to this extra volume when calculating strike temps.  For this reason as well as wanting a bit more control (I'm in a cold windy coastal area), I needed the ability to heat the mash.  The heat / viscosity issue has me wondering what the science is. 

Recirculating the mash - do you use a pump for that?  Any recommendations?

Thanks again all.

Offline hopfenundmalz

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Re: Mash temps?
« Reply #6 on: June 03, 2011, 09:02:43 AM »
I recirculate with a March pump.  If you don't have a pump, you can use a pot or pan to catch the liquid and put it on the top.
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Offline tschmidlin

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Re: Mash temps?
« Reply #7 on: June 03, 2011, 09:33:46 AM »
How I got here was that I add about 1/4 - 1/2 gallon of water to my grains before crushing and let it sit for an hour (the crush turns out quite differently as grains are more squished than crushed, I like it),
What kind of efficiency do you get doing this?  And when you don't do it?  What kind of mill?  Gap setting?
Tom Schmidlin

Offline surfin_mikeg

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Re: Mash temps?
« Reply #8 on: June 03, 2011, 12:18:28 PM »
Quote
What kind of efficiency do you get doing this?  And when you don't do it?  What kind of mill?  Gap setting?

I built a mill from skateboard wheels fitted onto 12" x 2" pipes, powered by a hand-drill, and it mounts to a table.  No $200 mills in my budget and I needed something that works when I need it.  I don't know the gap setting - I adjusted it such that when I run dry grain through it, it's pulverized on the first run.  When the grain is soft, there's a bit of that such that I know it's working.  The main thing is that I get no clogging or slow-down when draining the grain bed and it's easy to stir.  It's also a little nicer when mixing into the composter.   I did need to add plastic scrapers to the mill's underside for anything that sticks to the rollers.

I moisten the grain such that it is damp with no extra water pooling at the bottom, kinda like if you used a spray bottle, at the beginning when I'm getting setup & eating or whatever, and mix the water in by hand.  I also do not measure efficiency, but my typical target of a calculated 6% ABV at 75% come out stronger than that. 

It's working well but I do get a raised eye-brow or two at the homebrew meetings. ;-)

Offline tubercle

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Re: Mash temps?
« Reply #9 on: June 03, 2011, 05:14:12 PM »
Trust physics.  Mix and measure your water temp, know your grain temp.  Calculate your strike temp and trust it.  Leave the top on the cooler for the hour, cover the lid with a towel and keep it off of the floor.  It will work great.

This^^^^^

  You are only mashing for and hour or so. Don't get caught up in the panic of those that worry about things measured to 6 decimal places. Hit your temps, close it up and make good beer. Let thermodynamics and chemistry take care of the rest.

 Brewing has no worries if you let it,
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Offline euge

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Re: Mash temps?
« Reply #10 on: June 03, 2011, 06:45:05 PM »
Trust physics.  Mix and measure your water temp, know your grain temp.  Calculate your strike temp and trust it.  Leave the top on the cooler for the hour, cover the lid with a towel and keep it off of the floor.  It will work great.

This^^^^^

  You are only mashing for and hour or so. Don't get caught up in the panic of those that worry about things measured to 6 decimal places. Hit your temps, close it up and make good beer. Let thermodynamics and chemistry take care of the rest.

 Brewing has no worries if you let it,

I don't stir either once I'm happy withthe temp, and it hasn't affected the eff one bit. What's important is the actual mash temp not the water above it. Usually the water on top will drop at least a couple degrees, but the mash will stay consistent. For years I thought there was a variation/drop but after sticking the thermometer in real deep into the mash the truth was revealed. Try throwing a couple blankets or a sleeping bag over your tun to insulate it further. That ought to help.

+1 to tubercle's RDWHAHB philosophy. I try to emulate it. Sometimes I don't even bother to measure the gravity. :o
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Offline denny

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Re: Mash temps?
« Reply #11 on: June 04, 2011, 08:21:15 AM »
Brewing has no worries if you let it,

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Offline bluesman

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Re: Mash temps?
« Reply #12 on: June 04, 2011, 11:09:19 AM »
Trust physics.  Mix and measure your water temp, know your grain temp.  Calculate your strike temp and trust it.  Leave the top on the cooler for the hour, cover the lid with a towel and keep it off of the floor.  It will work great.

This^^^^^

  You are only mashing for and hour or so. Don't get caught up in the panic of those that worry about things measured to 6 decimal places. Hit your temps, close it up and make good beer. Let thermodynamics and chemistry take care of the rest.

 Brewing has no worries if you let it,

I have to agree with Tubercle.

If you are getting good conversion and hitting your temps initially then I wouldn't worry too much about losing a couple of degrees in the mash by the end of the cycle. The one measure that is most important is "how does your beer taste" and are you satisfied with the finished beer.
Ron Price

Offline Will's Swill

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Re: Mash temps?
« Reply #13 on: June 05, 2011, 08:36:25 AM »
If you're getting noticable heat stratification, then you are losing significant heat from somewhere.  The temp would remain pretty uniform (if it starts out uniform) over the course of a mash if you're not losing much heat.  I agree with others here that suggest you might want to insulate the top and bottom of the mash tun.  Recirculation will work, too, but that's another source of heat loss that you'll want to account for.
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Offline tubercle

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Re: Mash temps?
« Reply #14 on: June 05, 2011, 08:52:22 AM »
How I got here was that I add about 1/4 - 1/2 gallon of water to my grains before crushing and let it sit for an hour (the crush turns out quite differently as grains are more squished than crushed, I like it),
What kind of efficiency do you get doing this?  And when you don't do it?  What kind of mill?  Gap setting?

 I would like to hear the results of this compared to a "dry" crush. If they are squished and not broken open the enzymes might not be as effective as they could be. You might be giving up a lot of comversion. This goes way beyond the malt conditioning by slightly moisting the grain per the Kaiser.
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