Mash in kettle or cooler?

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AlexKay

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As the title says. I’ve always kept everything — heating water, mash, boil — in the same kettle. Lately I’ve been wondering if I should switch to an insulated cooler for the mash step in order to keep my temperatures more stable. Stability is particularly a problem for small batches (2.5 gallon, 1.25 gallon, and 0.25 gallon). What do y’all do?
 

IslandLizard

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Can you elaborate a bit more? So many factors to consider.

How big is that kettle? And how big are your batches mostly?
How do you heat, gas, electric, stove, burner, kettle elements, induction?

For small batches you can stick your kettle with the mash in a warm but turned off oven.
Mash and brew outside or indoors?

Any insulation around the kettle/lid/bottom?

Many brewers swear by BIAB. Also don't change a winning team.
 

madscientist451

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I started out BIAB, went to the cooler mash tun, fly sparge, batch sparge, no sparge then went back to BIAB but do a dunk sparge in a side pot. I use a smooth top range in the kitchen and wrap up the kettle in an old sweatshirt and don't have any temperature swings when doing 2.5 gallon+ batches. Smaller batches can be a problem, there just isn't enough thermal mass to hold temp if your house is cold like mine is. If you are doing 1.25 gallon batches, my advice would be to use all your water for the mash and bump up your thermal mass that way. 1.25 gallons beer + 1 gallon evaporation during boil, .25 gallon absorption and .5 gallon kettle waste/trub so start with 2.75 - 3 gallons of water.
 
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bracconiere

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(2.5 gallon, 1.25 gallon, and 0.25 gallon)

personaly, i'm kinda old school and still like coolers for my mashing...i'd use something like this for the batch sizes you're talking about... i think a bazooka tube, and ball valve would fit in it...

 
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AlexKay

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Can you elaborate a bit more? So many factors to consider.

How big is that kettle? And how big are your batches mostly?
How do you heat, gas, electric, stove, burner, kettle elements, induction?

For small batches you can stick your kettle with the mash in a warm but turned off oven.
Mash and brew outside or indoors?

Any insulation around the kettle/lid/bottom?

Many brewers swear by BIAB. Also don't change a winning team.
2.5 gallon batches are done with 4 gallons of water in a 6 gallon kettle. I’ll lose 2-3 degrees over the course of an hour mash.

1.5 gallon batches are done with just over 2 gallons in a 4 gallon kettle. 3-4 degrees down is the usual.

0.25 gallon batches are done with 80 oz of water in a 0.9 gallon asparagus steamer. Thermal mass is so low, and surface area to volume so high, I’ll lose well over 10 degrees in an hour.

Everything is done indoors on the kitchen electric range. I tried wrapping the 4 gallon kettle in Reflectix, and it actually made things worse (presumably because I was losing the thermal mass of the still warm heating element) — I could try again with many more layers, I suppose.

The oven is a good idea; I may give that a shot before worrying about coolers.
 

IslandLizard

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2.5 gallon batches are done with 4 gallons of water in a 6 gallon kettle. I’ll lose 2-3 degrees over the course of an hour mash.
That's not too bad, better than average I'd say. Any insulation around it and on top of the lid during the hour mash?

I doubt the 6 gallon kettle would fit inside your oven, so yes, some extra insulation would be helpful.
If you take the kettle off the stove during the mash, don't forget to put some insulation under the bottom. Putting it on a cold floor or countertop is a huge heat drain. And yes, you'd also lose the residual heat from the element the first 15-30 minutes. After that, the glass top likely becomes a heat drain itself.

1.5 gallon batches are done with just over 2 gallons in a 4 gallon kettle. 3-4 degrees down is the usual.
That one may fit inside your oven. I used to keep mash pots in the prewarmed oven when I did partial (30-50% all-grain) mashes. I would turn the oven on for 2-3 minutes half way through, and the mash temp was usually within 1-2°F of the target during the hour.

I like my 54 qt converted cooler for 5.5 (and the occasional 11) gallon batches, but it's tricky and it took some time and diligence to hit the mash temp right on the nose, erring in coming out a bit higher rather than being 1-2 degrees lower. It's much easier to cool it down by adding some cold water after stirring, than trying to raise the temps, even 2-4 degrees.

I still sometimes mash in the kettle (step and decoction mashes), and like having the benefit of being able to raise the temp by just turning the heat on for a few minutes while good stirring/bringing the bottom of the grist to the top, while scraping the bottom well to prevent scorching.

BTW, I also brew in the kitchen, using a 3500W induction plate on the countertop. Having the stove nearby is handy for boiling down extra wort and such.
 

Leezer

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I BIAB on my kitchen stove and cover my 4G kettle with an old blanket and 2 thick beach towels. The kettle stays on the stove (with the heat off) and I lose about 2 degrees over the course of an hour. So maybe more layers would help your situation.
 

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I mash in an insulated cooler and maintain mash temps within 1 deg. F by using a 120V RIMS with constant recirculation. This allows me to do step mashes as well. I boil in a seperate boil kettle using a Edelmetall burner fueled by natural gas.
 
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What do y’all do?
BIAB, 1.5 gal batches, 45 min mash, portable induction cook top, double wrap kettle with reflectix, cover the kettle lid with a bath towel. Temperature loss is 1F or 2F over 45 minutes for OG 50-60; did a barley wine (OG 90) where there was no temperature loss over 60 minutes.

For me, opening the kettle to measure the temperature results in a loss of ~ 1F - so I generally measure just at the start and the end of the mash.
 

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Instead of focusing on how to hold mash temps for an hour, why not find out what the length of time necessary for full conversion is and then focus on holding the mash temp for that amount of time. Hint: Full conversion depends on the quality of the grain milling just as mash efficiency does. Do a good job of milling and conversion happens quickly and fully. Do a poor job and conversion may never complete and efficiency will likewise suffer. I no longer insulate my kettle when I am waiting for conversion because the fine milling I do converts very quickly and thus the efficiency is in the 80-85% with no sparge. Add a sparge and the efficiency gets even higher.
 

Beermeister32

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0.25 gallon batches? 1 quart? Seems like that is too small for any sort of consistency, either materials or mashing.

IMHO, if I were doing a test batch, I think 2 gallons would be about the minimum size to begin getting consistent results before scaling up.
 
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AlexKay

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0.25 gallon batches? 1 quart? Seems like that is too small for any sort of consistency, either materials or mashing.

IMHO, if I were doing a test batch, I think 2 gallons would be about the minimum size to begin getting consistent results before scaling up.
Well, a quart is the amount that gets bottled (and bottling couldn't be easier: one 1 L EZ-Cap bottle and done). About 50 oz. goes into the fermenter. It's a good size to try an idea out in general terms, with the understanding that I'll have to fiddle a bit with things once I've scaled up to 2.5 gallons.

At what stage do you think inconsistency will be introduced? Salts, hops, and yeast (dry) are used in 0.1-2 g quantities, and I have a 10 mg scale. Grain absorption rate and boil-off rate are both highly predictable. The temperature drop during the mash is also highly predictable; it's just too large for what I want my process to be.

My experience the one time I made 12 ounce batches (4 batches, all variables the same except the maltster) is that they're pretty reproducible.
 
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At what stage do you think inconsistency will be introduced?
Find the answers to these questions:
  • How accurate (on a percentage basis) do the weight and volume measurements need to be?
  • What temperature ranges need to be maintained?
then prove that tools / equipment do not exist to meet those requirements
 
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AlexKay

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Instead of focusing on how to hold mash temps for an hour, why not find out what the length of time necessary for full conversion is and then focus on holding the mash temp for that amount of time. Hint: Full conversion depends on the quality of the grain milling just as mash efficiency does. Do a good job of milling and conversion happens quickly and fully. Do a poor job and conversion may never complete and efficiency will likewise suffer. I no longer insulate my kettle when I am waiting for conversion because the fine milling I do converts very quickly and thus the efficiency is in the 80-85% with no sparge. Add a sparge and the efficiency gets even higher.
Do you do an iodine test to monitor conversion? I agree that with a fine BIAB crush, I'm probably mashing longer than strictly necessary, but this way I can be pretty confident conversion has taken place and I can skip the test.
 
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AlexKay

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Find the answers to these questions:
  • How accurate (on a percentage basis) do the weight and volume measurements need to be?
  • What temperature ranges need to be maintained?
then prove that tools / equipment do not exist to meet those requirements
Yep, that's my point. Hops and yeast are added in gram quantities, so a 10 mg scale gives 1% accuracy. Salt quantities can go as low as 0.1 g for 10% accuracy, and I'll argue nobody is sensitive to such variations in salts.

I don't think the mash is inconsistent from batch to batch; it always drops about 12 degrees. My concern is just that this makes for a beta-amylase playground and a thin beer.

I'm optimistic about the oven idea, and will report back.
 
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I'm optimistic about the oven idea, and will report back.
The oven idea gained (or maybe regained) popularity over in "1 gal brewers unite" a couple of years ago. There were enough positive anecdotals to suggest that it works well for many (but not all) ovens.

My previous reply
Find the answers to these questions:
  • How accurate (on a percentage basis) do the weight and volume measurements need to be?
  • What temperature ranges need to be maintained?
then prove that tools / equipment do not exist to meet those requirements
was mostly an attempt to move the discussion from opinion to 'research' topics. And, as you know/suspect, those topics already have answers.
 

CascadesBrewer

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2.5 gallon batches are done with 4 gallons of water in a 6 gallon kettle. I’ll lose 2-3 degrees over the course of an hour mash.
1.5 gallon batches are done with just over 2 gallons in a 4 gallon kettle. 3-4 degrees down is the usual.
Rock stable mash temps seem to be about the most overblown aspect of brewing. I won't say they do not matter at all, but I suspect there is near zero difference in a beer with a stable mash temp vs one that drops 4F over a 1 hour mash.

I am also not convinced that mash temps even have much impact on the final outcome of the beer and I am quite confident the idea that "high mash = thick/sweet" and "low temp = thin/dry" concept is mostly a fallacy. If you think your beers are too thin, start a mash at 154F and the Beta Amylase will be denatured well before your mash temps start to drop below 151F. When I stopped looking at mash temp as a level over the character of my beer and looked at aspects like recipe, yeast, water chemistry, OG, etc. I found that I could actually start to have some control.
 
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AlexKay

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I am also not convinced that mash temps even have much impact on the final outcome of the beer and I am quite confident the idea that "high mash = thick/sweet" and "low temp = thin/dry" concept is mostly a fallacy.
Brulosophy (and I know not everyone likes Brulosophy) has done this four times that I could find, with marked differences in OG/FG every time and, three times out of four, an inability of tasters to tell the difference.

In my own beers, I've certainly noticed the effect of mash temperature on OG/FG. Also, I've certainly mashed low and made beers that I thought were too thin. (Note that I do not infer causation from this!) I'm continuing to experiment, and I have a bag of Carapils I'm going to deploy.
 

IslandLizard

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If you think your beers are too thin, start a mash at 154F and the Beta Amylase will be denatured well before your mash temps start to drop below 151F.
That's that idea, yes, and a good start.

Now on homebrew scale, IME, one may have to start at somewhat higher temps than that (156-160F). You'd need hold it there for quite some time 5-15 minutes, in order to see the effects of denaturing much of the beta amylase as it gets released. That way mostly alpha amylase is left to do the job with far less beta amylase activity left to gnaw the ends off (which creates fermentables).

How long you need to keep it at those higher temps during those first 5-15 minutes of the mash depends on the grist fineness, agitation, and intended fermentability of the resulting wort.
 

RM-MN

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Do you do an iodine test to monitor conversion? I agree that with a fine BIAB crush, I'm probably mashing longer than strictly necessary, but this way I can be pretty confident conversion has taken place and I can skip the test.
I have done several experimental batches where I used iodine to determine if I had full conversion. I suggest you try it for yourself. Make sure to have particles of grain in your sample before you add iodine as that is where the unconverted starch will be. I'd suggest you take your first sample at 5 minutes and at every 5 minutes until the iodine no longer turns blue. My first time I did the testing that way. The next time I started much sooner.
 

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I mostly do BIAB 2.5 to 3.5 gallon batches on my gas stove top. I made a Reflectix wrap for my kettle a few years ago, and while it did help a little, I eventually scrapped it.

Now, I just cover the kettle with a large towel and stir the mash a few times (about every 10 minutes during a 45 minute mash). I check the temp and apply heat while stirring if necessary to get the temp back to where I want it. It's not usually off by more than a degree, but doing this keeps the mash temp pretty consistent with the added benefit of better efficiency from stirring.
 

bracconiere

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just had a new thought....what about a sous vide and double boiler sorta thing? or just a heating element and temp probe for the water bath?

(still catching up, sorry if that's been said allready)
 

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Or a PID controller and an immersion heating element. All kinds of ways to MacGyver up a temperature controlled/managed environment. With a double boiler set up you could even do a step mash by putting heat into the bath water. As long as the volume of your bath water is large enough you'll have a pretty stable environment.
 

hamachi

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As the title says. I’ve always kept everything — heating water, mash, boil — in the same kettle. Lately I’ve been wondering if I should switch to an insulated cooler for the mash step in order to keep my temperatures more stable. Stability is particularly a problem for small batches (2.5 gallon, 1.25 gallon, and 0.25 gallon). What do y’all do?
After a few extract batches and one batch of BIAB in the pot, every batch of mine since then has been MIAB in a 10 gallon cooler. It gives me good temperature stability and lets me try weird experiments like cold mashing without ending up with a bunch of sludge in the pot. I also don't need a pulley system above the pot to hoist the bag, so I can do everything in the kitchen.

While I will do split batches as small as 1.5 L, my smallest total batch size is 2.5 gallons, which corresponds to about 2.5 gal strike water before batch sparging. If you wish to do tiny 1 quart batches, I imagine you'd need a much smaller cooler, and the temperature stability might not be great with that much less thermal mass. For that small a batch, the oven suggestion sounds like a good one. Or maybe get one of those Yeti double-walled metal bottles which maintain temperature extremely well. But a 46 ounce Yeti costs as much as a 10 gallon plastic cooler, so they ain't cheap.
 
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