Cooler Mash Tun

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BrianB

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I'm interested in doing an All-Grain brew and was wondering what size cooler I would need for a Mash Tun if I'm going to do a 5 gal batch?
 
I have a 52 Qt (13 Gallon) Coleman Xtreme that has been pretty close to being maxed out on some very high gravity 5 gallon batches.

If you know how much grain a batch needs and your mash thickness, the "Can I Mash It?" calculator is handy to help figure out if your tun is big enough.

https://web.archive.org/web/20201111195637/https://www.rackers.org/calcs.shtml
Also, if you're looking for a general purpose (integrated) brewing spreadheet, BrewCipher will warn you if your recipe will exceed your tun's capacity.
 
I have a 52 Qt (13 Gallon) Coleman Xtreme that has been pretty close to being maxed out on some very high gravity 5 gallon batches.

If you know how much grain a batch needs and your mash thickness, the "Can I Mash It?" calculator is handy to help figure out if your tun is big enough.

https://web.archive.org/web/20201111195637/https://www.rackers.org/calcs.shtml
Also, if you're looking for a general purpose (integrated) brewing spreadheet, BrewCipher will warn you if your recipe will exceed your tun's capacity.
VikeMan - thanks much. I didn't know that the calculators / spreadsheets would do that for you. Great recommendation.
 
I have a 52 Qt (13 Gallon) Coleman Xtreme that has been pretty close to being maxed out on some very high gravity 5 gallon batches.
I also have a Coleman Extreme, about that same size. The beauty is, the drain is slightly recessed (in the bottom), so you can drain the tun completely, which I find very important.

The CPVC manifold is shown upside down, for illustration:
CPVC Manifold_1200.jpg

CPVC Manifold_Detail_1200.jpg
 
I also have a Coleman Extreme, about that same size. The beauty is, the drain is slightly recessed (in the bottom), so you can drain the tun completely, which I find very important.

The CPVC manifold is shown upside down, for illustration:
View attachment 828863
View attachment 828864
Nice setup. Is that a SS threaded bulkhead fitting? Dry-fit CPVC? And did you use a bag too?

(I started with a 8gal pot on stove, never did cooler mash. I had the impression people just jammed a SS braid onto the cylinder gatorade tap.)
 
I also use(d) the Coleman Extreme before going BIAB. Looks like same manifold design. I went with 72 qt per YouTuber Beer-N-BBQ by Larry. He measured the 52 qt and found it didn't hold 52 qts.
I previously used the 10 Gal HD cooler. After a couple stuck mashes I said "F" this. Much happier with the manifold design. Of course, you could do a manifold in the 10 Gal, but much smaller footprint to use.
 
@IslandLizard - Nice! I assume you handmade the manifold? If so, how did you make the cuts / slots in the PVC pipe?
Yeah I did, back in 2013.
I got the "plans" from someone who posted that manifold design for a 70-some qt rectangular cooler. Not sure where I saw it, could have been elsewhere than here on HBT. I just scaled it down.

I used a thin kerf plywood/veneer circular saw blade in a circular saw. I then mounted the saw upside down to cut the slits while seeing what I was doing.

Is that a SS threaded bulkhead fitting? Dry-fit CPVC? And did you use a bag too?
Yes, it is, threaded all the way.

I ended up having to use some silicone between the inside cooler wall and the rubber o-ring to make a better seal.
The biggest issue is that the cooler walls compress when tightening the bulkhead nut. I stuck a short piece of plastic conduit in the hole to be able to tighten the nut quite a bit more. The bulkhead assembly still tends to rotate a bit when I'm not careful.

Yup, dry fit CPVC. Sometimes it comes apart when emptying the tun. ;)

No, I don't use a bag, it's not needed.
I do vorlauf the first gallon or so of each of the runnings to catch any bits and cloudiness, and start lautering slowly. Once the wort runs clear, I can open the valve pretty much all the way.

Occasionally I still do step-mashes, cereal mashes, and even decoctions in the kettle, under direct heat (induction plate). The tun is the lautering/sparge and holding vessel in those situations.

Earlier this week I did a 10 pound cereal mash (including the final boil) using 50% flaked wheat, 50% Pilsner, in the kettle. When the entire mash was completed, did a mashout, and transferred everything to the tun, scooping with a long handled gallon kitchen pot, for lautering and sparging. It was a little sticky, but ended up not having to use rice hulls. Drained like a charm!
 
previously used the 10 Gal HD cooler. After a couple stuck mashes I said "F" this. Much happier with the manifold design. Of course, you could do a manifold in the 10 Gal, but much smaller footprint to use.
I've seen some copper and stainless "manifolds," even round ones (!), with slots or many small holes drilled in the bottom.

The main issue with the round gott is the placement of the outlet being an inch or so above the bottom. It's very difficult to drain it completely, especially toward the end of lautering, when the flow reduces, it tends to lose prime. Toward the end of the lauter, tilting toward the spigot can help.
 
A ten gallon cooler will satisfy most five gallon batches. I bought a ten gallon cooler because people told me I'd want to go bigger over time. I ended up going smaller.
 
I still have my HD cooler too. I shoe-horned an 11 gallon Bayou Classic kettle in it a couple of years later after seeing another member do it. Same with the etched volume markings. I added Adventures In Homebrewing's false bottom. I like it because of the stainless tubing instead of silicone. Pics are from about 10 years ago. Yep, it continues to serve me well.
New Mash Tun 02.jpg


New Mash Tun 01.jpg
 
I do all of my 5 gal batches in a cheap 5 gal Igloo Cooler. It works perfect although I rarely do bigger beers > 7.0 % ABV's. I can't even remember the last time that I didn't hit my goal efficiencies and numbers right on the money now that I have my processes down. The $25 round Igloo cooler off the shelf at Walmart has worked great for me.

I did spend a little more money to buy a high quality stainless steel false bottom for it that works perfect. I have never had any issues with stuck spares as long as I carefully adjust the false bottom in the cooler. I would rather have a 5 gal cheaper cooler with a good false bottom than a bigger 10 gal cooler with a cheap false bottom (PVC, etc.).
 
Funny I should see this thread. I have had a 10 gallon rectangular cooler that I bought used for about 20 bucks for almost a year now. I keep meaning to try it out as I bought tubing and a valve for it, but never did. Well, I used it as a sparge tank this last brew. It worked really well, but not sure how it would do as a mash tun as it went from about 180 degrees when I started the sparge, to about 170 after it hit the grain, then about 15 mins later is was down to about 150 or so. For a sparge setup it worked awesome, but I need to figure out how to keep the temp better for a 60 min mash. But, it was cool and easy has heck to clean up
 
Funny I should see this thread. I have had a 10 gallon rectangular cooler that I bought used for about 20 bucks for almost a year now. I keep meaning to try it out as I bought tubing and a valve for it, but never did. Well, I used it as a sparge tank this last brew. It worked really well, but not sure how it would do as a mash tun as it went from about 180 degrees when I started the sparge, to about 170 after it hit the grain, then about 15 mins later is was down to about 150 or so. For a sparge setup it worked awesome, but I need to figure out how to keep the temp better for a 60 min mash. But, it was cool and easy has heck to clean up
For sparging, the water temp is not all that critical. You can sparge at low temps or high ones, with very small, or no differences to the outcome.

If you really want to perform a mashout starting from your mash temp, you should be able to do that too. But it takes an extraordinary amount of hot (boiling) water to do that, which is water that will not be available for sparging, and will affect your ultimate mash efficiency in a negative way.

A decent brewing software should be able to let you set some critical mash tun parameters (such as its specific heat) to get very close to predicting your strike water temp needed for hitting your ultimate mash temp spot on, once mixed.

That said, I've not found one that will easily calculate needed strike water temps when underletting your grist. For example, I empirically landed on needing 5 gallons of 178F strike water when underletting, ending up at a mash temp of exactly 154F, with 14 lbs of grist in the tun, at a mash thickness of 1.5 quarts per pound of grist. That's with all starting at typical room temps of say 68F. I just tweaked BeerSmith's mash tun settings in the equipment profile to give me that result.
 
A decent brewing software should be able to let you set some critical mash tun parameters (such as its specific heat) to get very close to predicting your strike water temp needed for hitting your ultimate mash temp spot on, once mixed.

That said, I've not found one that will easily calculate needed strike water temps when underletting your grist.

Sounds like a heat loss issue during a top fill (open tun) vs. underletting (covered tun). Are you covering the tun while underletting? If so, I'm curious...how much difference are you seeing between the two?

It does seem like the tun's specific heat parameter (or whatever it's called in Beersmith) or the "Mash Tun Initial Heat Absorption Value" in BrewCipher would be the best available way to compensate. Ideally, there would be an "Open Tun Fill Heat Escape" parameter that applies when not underletting, but I'm not sure the juice would be worth the squeeze, thus my curiosity.
 
Last edited:
Yeah I did, back in 2013.
I got the "plans" from someone who posted that manifold design for a 70-some qt rectangular cooler. Not sure where I saw it, could have been elsewhere than here on HBT. I just scaled it down.

I used a thin kerf plywood/veneer circular saw blade in a circular saw. I then mounted the saw upside down to cut the slits while seeing what I was doing.


Yes, it is, threaded all the way.

I ended up having to use some silicone between the inside cooler wall and the rubber o-ring to make a better seal.
The biggest issue is that the cooler walls compress when tightening the bulkhead nut. I stuck a short piece of plastic conduit in the hole to be able to tighten the nut quite a bit more. The bulkhead assembly still tends to rotate a bit when I'm not careful.

Yup, dry fit CPVC. Sometimes it comes apart when emptying the tun. ;)

No, I don't use a bag, it's not needed.
I do vorlauf the first gallon or so of each of the runnings to catch any bits and cloudiness, and start lautering slowly. Once the wort runs clear, I can open the valve pretty much all the way.

Occasionally I still do step-mashes, cereal mashes, and even decoctions in the kettle, under direct heat (induction plate). The tun is the lautering/sparge and holding vessel in those situations.

Earlier this week I did a 10 pound cereal mash (including the final boil) using 50% flaked wheat, 50% Pilsner, in the kettle. When the entire mash was completed, did a mashout, and transferred everything to the tun, scooping with a long handled gallon kitchen pot, for lautering and sparging. It was a little sticky, but ended up not having to use rice hulls. Drained like a charm!
@Island Lizard - thanks much for the reply. Looks fairly straight forward.
 
I still have my HD cooler too. I shoe-horned an 11 gallon Bayou Classic kettle in it a couple of years later after seeing another member do it. Same with the etched volume markings. I added Adventures In Homebrewing's false bottom. I like it because of the stainless tubing instead of silicone. Pics are from about 10 years ago. Yep, it continues to serve me well.View attachment 828916

View attachment 828915
@Yesfan - very interesting idea.
 
@Island Lizard - thanks much for the reply. Looks fairly straight forward.
I built the same mash tun cooler but from a 120 quart Coleman extreme. The same manifold using 1/2" CPVC pipe and fittings, also dry fitted. I used a hack saw to cut the slots. It took some time but it worked fine.

The pipe, fittings and the CPVC to stainless steel adapter came from Menards but Home Depot or Lowes would everything too. On the outside I installed a ball valve and also had to use a large gasket between it and the cooler. In the top lid of the cooler I installed a thermometer and a sparge spray piece. I hard use that since I do full volume batch sparge.

I brew ten gallon batches and this setup has served well for many years. Just last week I removed the manifold from the mash tun and used it to keep the freezer items cold while I defrosted the freezer. Dual purpose.

Here's that transition piece, CPVC to stainless steel 1/2 pipe thread:
1694350380656.png
 
Sounds like a heat loss issue during a top fill (open tun) vs. underletting (covered tun). Are you covering the tun while underletting? If so, I'm curious...how much difference are you seeing between the two?

It does seem like the tun's specific heat parameter (or whatever it's called in Beersmith) or the "Mash Tun Initial Heat Absorption Value" in BrewCipher would be the best available way to compensate. Ideally, there would be an "Open Tun Fill Heat Escape" parameter that applies when not underletting, but I'm not sure the juice would be worth the squeeze, thus my curiosity.
If that was for me, I don't understand what you mean by underletting? I read up that some will put a layer of insulation foam on the lid to make up for the dead space between the mash and the lid to help keep the heat in. I might try that.
 
In place of the manifold, I found a easy to do setup on another forum. It is simply a supply hose for a dishwasher, cut off the end and slip the rubber part out. Crimp one end of the mess that you have left with, and slip a hose thru the bung of the cooler and slide it into the steel mess and use a hose clamp to keep it tight. I ended up buying a simple nylon valve off amazon for like 10 bucks for a pack of three, a 10 foot length of hose and done. It works perfect, and I think I used 3/8 inch tubing that slips into the bung of the cooler without even having to remove it. For under 50 bucks I have what I think will be a cool sparge tank. If you are interested in the link, here is it.

http://www.dennybrew.com/
 
While you wait to gather all the parts you need (want?) for your cooler mash tun, consider doing a batch BIAB. Paint strainer bags are readily available and cheap. You might decide that this is an easier route than the cooler once you try it.
Or maybe put the brew bag in a cooler. Ease of BIAB and temp stability of a cooler mash tun.
 
I don't understand what you mean by underletting?
Underletting is when you fill your mash tun from the bottom up, like through the drain valve rather than just pouring the heated water in from the top.

On my system with the elevated HLT, I fill through the open drain valve and manifold in the bottom of the mash tun. The idea is you have less chance for dough balls. That's clumps of grain that are not mixed thoroughly with the water. I can also keep the cover on to minimize heat loss during the filling.
 
While you wait to gather all the parts you need (want?) for your cooler mash tun, consider doing a batch BIAB. Paint strainer bags are readily available and cheap. You might decide that this is an easier route than the cooler once you try it.
Or maybe put the brew bag in a cooler. Ease of BIAB and temp stability of a cooler mash tun.

These are very valid suggestions!
They also touch on different approaches/philosophies to mashing/brewing. The one vessel vs. 2 vessel choice, and variations thereof.

One mash method that works well for one may not work for another, for several reasons.
Either method, including hybrid versions, is worth considering. So do spend some time ahead doing research, helping you to make the right decision, before going one way or another.

IIRC, we have some (older) threads where pros and cons of either method are weighed. There seems to be much personal preference, not all that much hard science, to which method a brewer clings to.
 
I should have asked @BrianB specifically. I was going to suggest just doing BIAB if the boil kettle is big enough. Skip the cooler.
@Bobby_M - I recently acquired a 6.5 gal cooler from a family member who no longer wanted it. Wasn't sure if a 5 gal all grain bill would be OK in that size cooler of if it would be too small.
 
@Bobby_M - I recently acquired a 6.5 gal cooler from a family member who no longer wanted it. Wasn't sure if a 5 gal all grain bill would be OK in that size cooler of if it would be too small.
Using @VikeMan's link to the Can I Mash It calculator:
Green Bay Rackers--Mash Calculators
You can mash 13 lbs of grist at a thickness of 1.5 qts (of water) / pound (of grist) in that tun, taking up almost 6 gallons of space. That leaves half a gallon of room (headspace) to stir (very carefully).

At 1.25 qts/lb mash thickness it would be 15 lbs. That's about as thick as you'd wanna mash.
Batch sparging (2x) is paramount to get a decent mash/lauter efficiency at those mash thicknesses.

13lbs of grist in a 5 gallon batch should yield an OG of 1.070, after an hour boil.
15 lbs for an OG of 1.080.

The majority of beers are under 1.065.
 
I recently acquired a 6.5 gal cooler from a family member who no longer wanted it. Wasn't sure if a 5 gal all grain bill would be OK in that size cooler of if it would be too small.
Is that a round cooler?
Can you perhaps post a picture, also of the inside, so we can see the spigot outlet?

Mind, 5 gallon is an arbitrary volume. You can brew 2, 3 or 4 gallons, especially when beginning or experimenting. By brewing more often you'll get more hands-on experience, while smaller batches will give you opportunities for more variety (different styles or ingredients) while reducing the chances of getting stuck with large amounts of not-so-good beer.
 
Using @VikeMan's link to the Can I Mash It calculator:

You can mash 13 lbs of grist at a thickness of 1.5 qts (of water) / pound (of grist) in that tun, taking up almost 6 gallons of space. That leaves half a gallon of room (headspace) to stir (very carefully).

At 1.25 qts/lb mash thickness it would be 15 lbs. That's about as thick as you'd wanna mash.
Batch sparging (2x) is paramount to get a decent mash/lauter efficiency at those mash thicknesses.

13lbs of grist in a 5 gallon batch should yield an OG of 1.070, after an hour boil.
15 lbs for an OG of 1.080.

The majority of beers are under 1.065.
@Lizard Island - thanks much. This is very helpful. I didn't know there was a Mash Calulator - that's great! I'm interested in trying all-grain. I've been watching videos and have seen a lot of home brewers using coolers for mashing and sparging and since I got this cooler for free, I wanted to try that approach for my next brew. I've been looking on line at the options and equipment needed to conver it and it looks pretty simple. Thanks again.
 
I hope after all these ideas we didn't scare Brian away from brewing . . .
@OakIslandBrewery - absolutely not. I am a newbie, just recently brewed my first homebrew after my son bought me a started kit for Father's Day. It turned out really well - a Hazy IPA with Mango and Vanilla extract. Everyone in the family liked it. I'd like to try it again with an all-grain kit instead of LME. I really like the idea of the all-in-one electric brew systems like the Brewvilla Gen 4, but that's pretty expensive, so while I'm learning, thought I'd try the cheaper path using coolers. I like the idea of the coolers as it seems to keep the mash temp pretty stable. I had trouble keeping the temp on my kettle stable on my gas burner so am thinking this might be a better approach for mashing.
 
All grain definitely opens a few more doors in your brewing experience. I made the switch in 2003 and have loved it ever since.

I must say brewing with extracts or partial mash gives a new brewer valuable insights into the hobby before spending more cash. Plus you get to fine tune and learn procedures that will carry over into the all grain world.

You are a lucky dad to have such a thoughtful son!

Good luck and keep the questions and comments coming.
 

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