Turning my smaller kettle into a malt pipe

[Ashv1]

[Moved to the appropriate "Kettles, Mash Tuns & Hot Liquor Tanks" DIY subforum --Mod]

After using a 30 liter (8ish gallon) aluminum kettle for many years i just got a bigger one to make life easier (50 liter, 13ish gallon).
now i'm thinking about turning the small one into the malt pipe. most designs i've seen have a detachable bottom mesh screen but i've heard there are permanent ones too.
from what i've gathered the most efficient design is to only have holes on the bottom and keeping the sides untouched which makes sense. but is there any flaws with this design? maybe higher risk of getting a stuck mash?
in terms of hole sizes i think BrewZilla for instance has 1.5 mm holes. is this a good size? my next question is how far apart should the holes be?
a concern that i have is there are solder joints outside of the kettle, in normal usage your wort is not in contact with them, but if i were to use it as malt pipe i have to submerge it in the bigger kettle and there's gonna be contact between wort and the joints. based on my research the solder material should be an aluminum/zinc/silicon based alloy therefore not harmful or toxic. should i be worried though?
and last thing is i think i have to remove the handles, otherwise i end up with a huge gap between the bottom of small kettle and the bottom of large kettle. using a torch that gets hot enough should suffice, right?
by the way i'm gonna use a bag inside of the pipe at least for now, but i want to be able to use the malt pipe without the bag too.

 

[IslandLizard]

Looks like the bottom of the kettle was formed together with the sides (giving the round corner), there's no weld or seam there from what I can see.
The bottom support ring is just tacked/welded* on. I'd say that should hold together for a long time.

* Not sure if the bottom ring and handles are welded or soldered on. Maybe someone can confirm one or the other, and how to remove the handles.
I know aluminum boil kettles used in brewing get an dark gray oxide layer on them, that protects the underlying metal from being dissolved over time. Not sure if the same happens during the mash. You may need to boil some water first to put the oxide layer on the outside of the malt pipe.

How thick is the bottom? Once you drill holes in it, it's structural integrity will be reduced, it may bow out (stretch) over time due to the weight of the (wet) grist that's exerted on it.

 

[Ashv1]

Looks like the bottom of the kettle was formed together with the sides (giving the round corner), there's no weld or seam there from what I can see.

Exactly, apparently they start with a disk and slowly shape it into a cylinder.

The bottom support ring is just tacked/welded* on. I'd say that should hold together for a long time.

* Not sure if the bottom ring and handles are welded or soldered on. Maybe someone can confirm one or the other, and how to remove the handles.

Bottom ring is just for aesthetics and adding a little bit of stability, actually these are not sold as kettles, these are sold as "kebab skewer holders". yes! some of the skewers are that big!
I'm no welding/soldering expert either but judging by the way they look i thought they might be soldered on, and i've read soldering aluminum is much easier than welding it. either way an angle grinder would do the job but if they're soldered on using a torch would be easier and cleaner. the ring can be removed too since it doesn't have any functionality, but with the ring i can use my S shaped hooks, if i remove the ring i have to opt for a Clawhammer type hook.

You may need to boil some water first to put the oxide layer on the outside of the malt pipe

That's a good idea

How thick is the bottom? Once you drill holes in it, it's structural integrity will be reduced, it may bow out (stretch) over time due to the weight of the (wet) grist that's exerted on it.

about 3mm , luckily i bought that 10 years ago, back then they didn't have to cut so much corners. the new one that i just got feels like a trash can compared to the old one. i think it'll be rigid enough, but obviously it depends on how far apart the holes are going to be.

 

[Yesfan]

You think it would be better to just use a mesh basket and find some flashing that you can just roll into a cylinder? put that on the inside of the basket and that would force the wert to drain at the bottom.

I think @odie does something similar with the basket that comes with a lot of Bayou Classic kettles.

 

[Ashv1]

You think it would be better to just use a mesh basket and find some flashing that you can just roll into a cylinder? put that on the inside of the basket and that would force the wert to drain at the bottom.

Problem is where i live i don't have those type of baskets available to me, the best thing that i can make a malt pipe out of is my old kettle

I think @odie does something similar with the basket that comes with a lot of Bayou Classic kettles.

Actually i have seen what odie does

View attachment 772945

 

[IslandLizard]

[... bottom thickness] about 3mm

That's pretty thick and sturdy. Sorry to see you waste such a darn good kettle...
Are you going to use the malt pipe to recirculate the mash, or just to drain it, rather than using a nylon bag?

I guess you could drill a few hundred 3 mm holes in the bottom, leaving at least 3 mm of aluminum (material) between them. If you can, use a drill press for the most precision and getting straight, perpendicular holes. You got some connections with a metal/fabrication shop?

 

[Ashv1]

That's pretty thick and sturdy. Sorry to see you waste such a darn good kettle...

Now that i think about it might be even thicker, sides are 3mm, but as i said since they start with a disk the base might be thicker. i guess we'll find out later!
idk, is it a waste really? i have to make the pipe out of something eventually. at first i wasn't sure either, but i realized i have no use for it, even if i decide to sparge time to time i won't need such a big kettle. as a hobbyist i'm careful not to become a hoarder. i still have a 40 liter cooler that i was going to turn it into a mash tun and bunch of other stuff that i need to get rid of. either i had to sell it as a scrap for cheap and find something to make a pipe with which definitely would have cost me more, or to keep it in my small apartment occupying space i don't have!

Are you going to use the malt pipe to recirculate the mash, or just to drain it, rather than using a nylon bag?

Plan is to recirculate, that is if my small "food grade" pump is up to the task. i did a test run and recirculated water at 67 C (153 F) for about 20 minutes and it did a decent job, though it got really hot which was expected. tbh i don't have much faith in it, i feel it's gonna fail during the first mash, but i hope i'm wrong.
Regarding using a bag this is what happened: i was gonna use only a bag for my first couple of brews to see how things pan out, i ordered the bag based on the dimensions on their website, when i received the bag i noticed the height is much shorter (it was supposed to be 67cm but turned out to be 45) so the grist would hang and obviously that wasn't a good thing for many reasons, so i knew i needed some sort of false bottom, soon i realized jerryrigging a false bottom not gonna be as cheap as i thought, and even if that's taken care of, sparging a bag would be a huge pain and inefficient (quality of our malt is not up to standard so we have to do all we can to extract that last bit of sugar!) so long story short it just made sense to use what i already have to make something that solves the false bottom and the sparging issue altogether, and my bag fits perfectly into the small kettle.

I guess you could drill a few hundred 3 mm holes in the bottom, leaving at least 3 mm of aluminum (material) between them.

Thanks for the suggestion, isn't 3mm on the bigger side? i thought AIO systems use 2mm holes and i know for a fact that BrewZilla uses 1.5mm.
I think the best course of action is to print dots on a paper, adhere it to the bottom then drill the holes.

You got some connections with a metal/fabrication shop?

I do actually. even talked to them about the possibility of making a grain mill, showed them bunch of pictures and our conversation was promising. probably gonna open a thread about that in near future.

 

[Broken Crow]

i still have a 40 liter cooler that i was going to turn it into a mash tun and bunch of other stuff that i need to get rid of. either i had to sell it as a scrap for cheap and find something to make a pipe with which definitely would have cost me more, or to keep it in my small apartment occupying space i don't have!

Is space the sole issue for not using the cooler for a mash tun? It would probably be a lot easier to do, and with a recirculation pump you should me able to max out efficiency. I've seen that pump used successfully by a number of brewers online and even considered it myself as a recirc pump when planning my system. So; Why not the cooler you already have?

 

[IslandLizard]

Thanks for the suggestion, isn't 3mm on the bigger side? i thought AIO systems use 2mm holes and i know for a fact that BrewZilla uses 1.5mm.

Sorry, I just grabbed the 3 mm hole size out of thin air. Yes, use whatever hole size AIO systems use. Ask what people have to say about them, and their preferences. I don't do BIAB or AIO myself, but have brew friends who do.

sparging a bag would be a huge pain and inefficient (quality of our malt is not up to standard so we have to do all we can to extract that last bit of sugar!)

"Dunk sparging" that bag in a separate vessel, such as a large bucket or your smaller kettle (the one you're thinking of converting into a malt pipe) should give much better sparging results/efficiency than simple pour-overs.
And for higher gravity worts (say, over 1.050-60), definitely sparge twice!

But... if the quality of your malt is indeed low, finer milling and longer mashing, or step mashing, is the only way to raise conversion (extraction) efficiency.
A sparge can only rinse out the sugars the mash created in the first place, but are still trapped in the wet grist after the first lautering (draining). So concentrate on doing a good, "thorough" mash maximizing conversion, first. Then drain the bag (or pipe) as dry as you can. Then a dunk sparge would be better than any pour-over, IMO.

Your little pump is a hot water solar pump. Not sure what their maximum temp rating is, but I expect at least 180F/82C.
They're known to be quite durable, but can also suddenly fail without reason or warning.

 

[mac_1103]

Then a dunk sparge would be better than any pour-over, IMO.

This is probably just me being hyper-literal or something, but I'm not sure I get what you mean by "any pour-over." Are you saying that dunking my bag of mashed grain into 4 gallons of sparge water in a second vessel is better than pouring 4 gallons of sparge water into the drained mash vessel that the grain bag is already sitting in? Maybe I can't call it "dunk sparging" if I don't physically move the bag, but I'm not seeing a practical difference. Would "full-volume sparge" be a more accurate descriptor? Then again sparge literally means "to spray or sprinkle" so "dunk sparge" is already an oxymoron. We could call it flushing, but I think most people prefer to save that for after they drink the finished product.

We now return you to your regularly scheduled programming.

 

[Ashv1]

Is space the sole issue for not using the cooler for a mash tun? It would probably be a lot easier to do, and with a recirculation pump you should me able to max out efficiency. I've seen that pump used successfully by a number of brewers online and even considered it myself as a recirc pump when planning my system. So; Why not the cooler you already have?

There are multiple issues, space is definitely one, the other problem is the cooler itself, the spigot hole design (or the lack thereof i should say) is just stupid, they have just drilled a hole through the cooler without narrowing the walls (i'll attach a photo) because of that you'll never get a good seal, the more you tighten the nut the more walls come together. and the ball valve has so much play too. all that being said i tested it with warm water and obviously it leaked, but wasn't like water was pouring out, it was dripping at a slow rate. maybe during a 60 min mash one tablespoon worth of wort would be lost. but leaking means wort goes between the walls and in the styrofoam and it's gonna turn into a petri dish. the other problem is about efficiency (what IslandLizard alluded to) knowing my malt is undermodified and lacks in quality, step mashing always was on my radar and obviously raising the temperature in a cooler is not possible, so soon after buying the cooler i realized i have to switch to another system.
I'm glad to hear what you said about the pump, that makes me more hopeful.

Sorry, I just grabbed the 3 mm hole size out of thin air. Yes, use whatever hole size AIO systems use. Ask what people have to say about them, and their preferences. I don't do BIAB or AIO myself, but have brew friends who do.

No problem, i'm happy to hear any suggestions. where's the best place to ask people about their system? and if you don't mind me asking what system do you use? 3 vessel?

"Dunk sparging" that bag in a separate vessel, such as a large bucket or your smaller kettle (the one you're thinking of converting into a malt pipe) should give much better sparging results/efficiency than simple pour-overs.

Yeah, i've seen people do that too, even some people do it in a bucket with room temp water and seems to work for them. definitely an option.

But... if the quality of your malt is indeed low, finer milling and longer mashing, or step mashing, is the only way to raise conversion (extraction) efficiency.

That's exactly why i'm planning to mill the grains myself, with a bag i can get away with much finer mill. in terms of step mash you're right again, that's the main reason i didn't utilize the cooler.

Your little pump is a hot water solar pump. Not sure what their maximum temp rating is, but I expect at least 180F/82C.
They're known to be quite durable, but can also suddenly fail without reason or warning.

On the specification sheet it says 0 to 100C, but i was never gonna push it that high, if it works with normal mashing temps without problems i'll be more than happy.

 

[IslandLizard]

There are multiple issues, space is definitely one, the other problem is the cooler itself, the spigot hole design (or the lack thereof i should say) is just stupid, they have just drilled a hole through the cooler without narrowing the walls (i'll attach a photo) because of that you'll never get a good seal, the more you tighten the nut the more walls come together. and the ball valve has so much play too.

Thanks for the attached picture, I see what you mean. My cooler mash tun is similar.

I stuck a plastic bushing (a piece of conduit) inside that hole, through which I run the bulkhead. I can tighten it well enough to prevent the valve from turning. You would need to find something that fits that hole as well as possible, you can then silicone or cement it in there.

BTW, how high up is that hole from the inside bottom?
If it's relative high up, it won't drain the cooler all the way unless you tilt the cooler toward the valve, at the end of lautering (draining). Stick a piece of wood or a brick under the opposite end.

 

[Komodo]

I've been building a BAIB system based on the Brew Hardware version, but I really wanted a malt pipe vs a bag. I've gone through a few vessels to find one that fits inside the main kettle with as little dead space as possible. What I have now is a Spike 15 gallon kettle with a Brewer's Best 15 gallon with the bottom cut out in a pattern to give support to a perforated SS disc that sits inside the malt pipe. There is probably a 1/16" - 1/8" gap between the kettle walls, it fits almost like it was made this way. My only concern is if the inner one expands with heat and then you can't pull it out, but I don't think that'll be an issue. I'll post pics here in a bit.

 

[Ashv1]

My cooler mash tun is similar.

I thought i'd never see that incompetent design anywhere else lol.

I stuck a plastic bushing (a piece of conduit) inside that hole, through which I run the bulkhead. I can tighten it well enough to prevent the valve from turning. You would need to find something that fits that hole as well as possible, you can then silicone or cement it in there.

I was contemplating to do something along those lines too, but at the end of the day it was gonna be a cooler mash tun with its limitations.
since i haven't used it there's a chance i could sell it for a price close to a new one. maybe. then i could use the money for something else. i just hope at least it works with the spigot and washers it came with and doesn't leak so i can get rid of it.

BTW, how high up is that hole from the inside bottom?
If it's relative high up, it won't drain the cooler all the way unless you tilt the cooler toward the valve, at the end of lautering (draining). Stick a piece of wood or a brick under the opposite end.

It's not that high up, when i put my false bottom in, the silicone tube is parallel to the bottom of the cooler.

I've been building a BAIB system based on the Brew Hardware version, but I really wanted a malt pipe vs a bag. I've gone through a few vessels to find one that fits inside the main kettle with as little dead space as possible. What I have now is a Spike 15 gallon kettle with a Brewer's Best 15 gallon with the bottom cut out in a pattern to give support to a perforated SS disc that sits inside the malt pipe. There is probably a 1/16" - 1/8" gap between the kettle walls, it fits almost like it was made this way. My only concern is if the inner one expands with heat and then you can't pull it out, but I don't think that'll be an issue. I'll post pics here in a bit.

I'm glad you found something that works for you. i'd assume both kettles would expand together, i'd be surprised if that causes any problem.
do you have any idea what size are the holes in your perforated SS disc?

 

[Yesfan]

I've been building a BAIB system based on the Brew Hardware version, but I really wanted a malt pipe vs a bag. I've gone through a few vessels to find one that fits inside the main kettle with as little dead space as possible. What I have now is a Spike 15 gallon kettle with a Brewer's Best 15 gallon with the bottom cut out in a pattern to give support to a perforated SS disc that sits inside the malt pipe. There is probably a 1/16" - 1/8" gap between the kettle walls, it fits almost like it was made this way. My only concern is if the inner one expands with heat and then you can't pull it out, but I don't think that'll be an issue. I'll post pics here in a bit.

That's pretty slick!

 

[IslandLizard]

I was contemplating to do something along those lines too, but at the end of the day it was gonna be a cooler mash tun with its limitations.

I don't see a cooler mash/lauter tun having inherent limitations for doing straightforward mashes and lauters (draining). It's very functional, insulated, and if a brewer wants it can be easily expanded/enhanced.

A brewer can do step mashes, cereal mashes, decoctions mashes etc. in the boil kettle, using the mash tun as the holding and later lautering/sparging device.

The brew-in-a-bag (BIAB) method came well after cooler mash tuns. The malt basket and later, malt pipe, are an "improved" version of the bag, and used in AIO brew kettles. It would be hard to sell an AIO with a floppy, drippy, messy mesh bag. The malt basket/malt pipe are a sophistication and can last the unit's lifetime. It can make recirculation mashes possible and thus step mashes easier, even automatic.

BIAB mashing is designed with the goal of a "full volume mash," no sparge.
"Sparge" meaning rinsing the grist after the mash is drained. BIAB mashing is a trade-off for ease of use over efficiency, as high gravity wort will remain trapped in the wet grist. Squeezing the bag will reduce that loss somewhat, but not as good as sparging the grist. And pour-overs aren't cutting it, they're nothing like a fly sparge, or any other sparge.

When I bought my Coleman "Extreme" cooler to convert to a mash tun, I had done some research, and made sure to get a model where the drain was recessed in the bottom. There's a little hollow, a well in the bottom where the drain is located. So there's zero dead space when draining.