false bottom for direct-fired recirculation mash?

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billtzk

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I'm building a direct-fired recirculating mash tun out of a 15.5 gallon sanke keg (part of my Brutus Ten clone project that is now underway) and I'm trying to decide what type of false bottom to use.

I know some people use copper and SS-braid manifolds in their mash tuns. Others use the stainless 10 to 15 inch diameter perforated stainless "disk" type false bottom with the pickup tube that goes down to the bottom of the keg through a hole in the center.

I'm inclined to go with the full perforated SS disk false bottom because it will keep the grain from direct contact with the bottom of my direct-fired mash tun. An SS-braid won't do that. I know that there are experienced brewers (e.g., BrewPastor, Monster Mash, to mention a couple who posted pics that I found while searching the forum), who use a SS braid, but I don't know how they heat their mash.

Which solution is likely to work best for a direct-fired mash?

EDIT: Price is not a factor. My DIY time, however, is very valuable as I'm spending a lot of time already to build my brew stand. I don't want to spend my time on a DIY solution (e.g., ss-braid / copper manifold) unless it is likely to be significantly better (less chance of scorching, higher yields, less likely to get stuck) for my direct-fired mash.
 
I use a FB, but it doesn't cover the entire bottom. I imagine the full FB may allow the most even temps across the grain bed, but if you're recirculating, it probably doesn't make much difference. You're constantly pumping out the hotter wort while the cooler wort drains down. I think the key is heeping the heat low and slow. Here's a pic inside my MLT FWIW.

 
I think mine's only 9 or 10 inches. I don't have any complaints and it's worked fine for a direct-fired MLT. I've been recirculating for a few batches. Before that I just stirred while the heat was on. Worked fine, just more labor-intensive.

If you get that, here's a head's up. Put a hose clamp on your pickup tube to provide pressure against the FB to keep it tight against the bottom. If you get grains by the sides it's a stuck sparge and you'll be scooping your grains out. Ask me how I know. ;)
 
I am documenting the build of my Brutus Ten clone at each step and I'll post when I'm done. I'm pretty much following the description and parts from the BYO article last month.

I'm at stage 0.5 LOL. I have the metal sitting on my porch and I have about two-thirds of the various parts ordered. I'm expecting shipments from morebeer, cole-parmer, and mcmaster carr this week. I got the ASCO red hats on ebay and the burners from some place in New York. I'm using natural gas, not propane. I got the gas line to my back patio run a couple of weeks ago.

I've cut the stock on a chop saw. I should have bought a horizontal band saw cuz the chop saw doesn't make perfectly straight cuts. Oh well, I think I can dress it up with a hand grinder. I'm practicing welding on scrap right now. I'm just learning how to weld and I need more practice for sure. My welds look pretty bad.

I'm building my Brutus Ten clone from mild steel since stainless is too pricey. Meanwhile, I've got kegs and most of the parts to build the HLT and MLT and I already got a boil keggle.
 
Very cool. I plan to build a non-automated single tier stand this spring. I've had my 3-tier stand for a while, but I really like the idea of having everything low and accessible.

 
I too mash in a converted keg, ss false bottom, with direct heat and recirculation. I love this setup....step mash, mash out, & constant mash temps are relatively easily achieved (sure you're well aware if this is the design you're going for).

WRT to the false bottom, I would choose one that is flat and with out handles. Some options are domed, and some have handle welded on. This makes it harder to dough-in. My setup looks much like the one above, there is already a pick up tube and thermometer in the way when stirring the grains with a paddle. You can get around them pretty easily, but the addition of a handle would be cumbersome IMO, and a dome would make it hard to get a paddle on the sides.

The very best setup I've seen for this is a bottom valve. He drilled a hole dead center in the bottom of the keg, then a 90 degree ss elbow was welded on the outside bottom of the keg, with a long ss nipple and ball valve on the end. You have to cut a hole through the bottom skirt for the nipple, but it works really well. False bottom sits on top as show above, but there's no internal pick up tube. *If* I ever redesign my mash tun I'll prolly do this.
 
billtzk said:
Nice setup Lil' Sparky. Looks similar to this one that I was thinking about from Midwest - 11" Stainless Steel false bottom - for Sanke Keg. It's a little larger in diameter than yours appears to be, and it is inexpensive. Comes with a pickup tube.

Thats what I use with direct heat and recirculation. I have a hose clamp above it and below it and keep it pressed tight to the bottom so nothing gets under it.

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billtzk said:
My welds look pretty bad.
I wouldn't sweat how your welds "look". As long as you get good penetration and have little to no pitting, you'll have a sound enough weld for what your doing. And if you're going to really focus on cosmetics on the Brutus Stand, you may want to grind down the welds when you finish to make it smooth and give it the appearance of one continous piece of metal.

But, if you are going to make the integrated gas chamber in the frame like the one in the recent BYO issue, then those welds will need to be a little more precise. You'll need strong solid welds so that no gas leaks out.

What kind of welder are you using? If you are an inexperieced welder, a wire-feed would be the way to go. A wire-feed takes little practice to be able to lay down a decent weld. Even better if you can get ahold of a MIG welder. You'll get cleaner welds. A stick welder is a little more difficult for a beginner because of the constant shortening of the welding rod (electrode). You have to consistently adjust your distance from the work to compensate for the rod burning up and getting shorter.


If you have any welding questions I'm sure Yuri could help you as well, along with a few others.


Good Luck! We'll definitely want to see some pictures!:rockin:
 
ebeer said:
The very best setup I've seen for this is a bottom valve. He drilled a hole dead center in the bottom of the keg, then a 90 degree ss elbow was welded on the outside bottom of the keg, with a long ss nipple and ball valve on the end. You have to cut a hole through the bottom skirt for the nipple, but it works really well. False bottom sits on top as show above, but there's no internal pick up tube. *If* I ever redesign my mash tun I'll prolly do this.

It's funny, I had asked about this, both here and on my brewclub site and everyone who chimed in had concerns about the burner immediately scorching the wort in the pipe below the tun. I was well convinced due to how many people suggested against it. Now that I've been messing around with my natural gas multi-jet burners, I've found that I can remove some tips and plug them up to basically make any flame pattern I want. I could easily stop flames from directly hitting the drain tube. Of course, I figured this out AFTER I had all my kegs welded with traditional side bulkheads and drains. I still think there is no more complete drain than from the dead bottom. You could conceivably tack weld a false bottom into this style MLT and have nothing in the way of stirring other than your thermo. If you're recirculating, you wouldn't even need that in the way because you could measure the temp inline. UGH... never happy with what we got!
 
I recieved a keg for free that already had a coupler welded in the bottom. I couldn't figure out how to make it work, so I took it to the scrap yard. :(

I didn't like the thought of having a burner directly on any plumbing, and I didn't want to muck around with how to set up the support to allow for it.

I know I have very little loss in my MLT. I'm happy with what I've got (for now). :D
 
Bobby_M said:
It's funny, I had asked about this, both here and on my brewclub site and everyone who chimed in had concerns about the burner immediately scorching the wort in the pipe below the tun. I was well convinced due to how many people suggested against it. Now that I've been messing around with my natural gas multi-jet burners, I've found that I can remove some tips and plug them up to basically make any flame pattern I want. I could easily stop flames from directly hitting the drain tube. Of course, I figured this out AFTER I had all my kegs welded with traditional side bulkheads and drains. I still think there is no more complete drain than from the dead bottom. You could conceivably tack weld a false bottom into this style MLT and have nothing in the way of stirring other than your thermo. If you're recirculating, you wouldn't even need that in the way because you could measure the temp inline. UGH... never happy with what we got!

I would think that using constant recirculation through your mash would eliminate any scorching in the pipe because your are recirculating through the pipe as well. As a side note, the brewer I know who uses this set up has won multiple national awards (NHC etc).
 
ebeer said:
The very best setup I've seen for this is a bottom valve. He drilled a hole dead center in the bottom of the keg, then a 90 degree ss elbow was welded on the outside bottom of the keg, with a long ss nipple and ball valve on the end. You have to cut a hole through the bottom skirt for the nipple, but it works really well. False bottom sits on top as show above, but there's no internal pick up tube.

That's an interesting idea, but then you are heating the plumbing on the bottom directly with your burner. Teflon tape on the threads would burn. I wonder how that holds up against leaks in the long run?
 
Good question, but I don't think teflon tape should be applied for leak prevention. Ideally, well tapped/dyed parts should fit snuggly when screwed together tightly. Teflon tape as I understand it is merely a joint lubricant to aid in screwing and unscrewing.
 
talleymonster said:
What kind of welder are you using? If you are an inexperieced welder, a wire-feed would be the way to go.

Hobart Handler 187. It's a MIG and I'm doing GMAW. I've got a bottle of C25 and I'm using .030 wire. I had an electrician run a 230 volt circuit with the right type of outlet on it to my back patio where I'm welding.

I'm definitely new to welding, but I'm not having too much trouble. I practiced a lot yesterday and learned that it is possible to burn through .120 metal (11 gauge). It's a good thing I'm not welding automobile sheet metal. I backed off the voltage by one tap and increased the wire speed that that got around the burn-through problem.
 
ebeer said:
Good question, but I don't think teflon tape should be applied for leak prevention. Ideally, well tapped/dyed parts should fit snuggly when screwed together tightly. Teflon tape as I understand it is merely a joint lubricant to aid in screwing and unscrewing.

That's what I understand as well. If you try going dry, the threads bind before then can fully seat. The telflon tape lets you get a good extra full turn on the fittings to seal. Even if the teflon then burns up, it should be fine.

Like I mentioned, I'm using a ring burner with removable tips, I can have half moon of flame on each side of that pipe so I'd never have direct flame on the pipe anyway. Even so, as mentioned, only applying heat when the pump is running is a sure way to keep the pipe near your mash temp.
 
I think you will find it hard to get a good seal on any pipe thread without some type of joint compound. I haven't seen any yet that don't leak without something in there.
 
Pipe thread sealing with wort: once you brew with a plumbing system a bit, the cooked/dried/nasty wort will act as a sealant, no matter how bad it leaks before hand....drips will go away...

I use Teflon pipe dope that is an industrial-type Pipefitter's sealant. Loctite brand.

You're supposed to wind the tape in the same direction that you thread the fitting, so that you don't have the free end wanting to roll/bind up sorta thing, when you thread the fitting on...just FYI...

How long before people are using bottom drains and heating from the periphery? :D

I would still prefer a side exiting drain/valve and just NOT HEATING the MLT directly, to avoid any carmelization of sugars by direct heat-it may add flavor, and make BETTER beer for all I know, but heating the bottom drain with a burner just seems to be asking for issues. I'm in the Camp of keeping direct heat off the mash...I'm sure there is success, but it just plain bugs me to think of it as a way I want to practice...:confused: . Seems if you are burning sugar to any degree, it is hardening and not going into the fermenter...??
 
I honestly don't know if it has any effect. I'm going to be direct firing anyway you look at it, at least that's my plan. I intend to run the burner very low and recirculate a full flow.
 
Bobby_M said:
That's what I understand as well. If you try going dry, the threads bind before then can fully seat. The telflon tape lets you get a good extra full turn on the fittings to seal. Even if the teflon then burns up, it should be fine.

Like I mentioned, I'm using a ring burner with removable tips, I can have half moon of flame on each side of that pipe so I'd never have direct flame on the pipe anyway. Even so, as mentioned, only applying heat when the pump is running is a sure way to keep the pipe near your mash temp.
I did all of my pipe fittings(aside from the fuel) without teflon at all. I dipped them in vegetable oil and cranked them down tight. Not had a leak at all.
 
I've been contemplating how I'm going to be sure of a steady mash temp once I start using my Keg/MLT and get a pump. I really think the direct fired MLT is the simplest solution. My only concern is I currently have a Bazooka T Screen, so my grains would have direct contact with the bottom of the keg. If I try this this, I'd probably need to recirculate, and probably even still stir a few times while heating.

I thought it wasn't a good idea to disturb the grain bed much during the mash. Would stirring not be a good idea? Isn't recirculating still disturbing the grain bed?

**How do most people set up their return from the recirculation? Just let it pour back in through the inlet, or drape tube over the top? I figured I'd set up a QD for it eventually.
 
Stirring during the mash is fine you just might want to let it settle a little bit before you run off. I bought over size folding false bottoms and ground them to fit. Here is a pic of my return line it goes inside to an elbow and has a silicon hose that lays on top of the grain bed it works great.
Pat
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Ok so you just use a hose to bring it to the grain level. I guess it wouldn't really be a big deal even if the hose wasn't right on top of it. Thanks for the response.

That's a NICE rig you've got there! I'm working on polishing up and converting my sankes, to make a single tier. I'm sure I saw your rig in the sculpture thread, but can you post a link to addtl pics of it?
 
Ok so you just use a hose to bring it to the grain level. I guess it wouldn't really be a big deal even if the hose wasn't right on top of it. Thanks for the response.

That's a NICE rig you've got there! I'm working on polishing up and converting my sankes, to make a single tier. I'm sure I saw your rig in the sculpture thread, but can you post a link to addtl pics of it?

The hose is long enough to wrap around the keg so will work with 5 and 10 gallon batches.

Thanks there are two links on the bottom of this post.

Pat
 
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