MLT Manifold design critique

I'm in the process of making the jump to all grain. I purchased a 60 qt Igloo "Ice Cube" cooler for my MLT conversion and plan to fly sparge. Below is a pic of my initial design for the manifold (minus the slots or holes in the bottom of the tubing). Ultimately, I will have a stainless valve which will be connected to the hole you can see in the center of the manifold. I'm looking for any critique/improvement that can be completed with CPVC.

Thanks in advance!

everything i have read/heard is that pvc is not food grade and will add off flavors. i could be mistaken but would personally use something that i no is food safe. just my 2 cents.

mxman06 said:

everything i have read/heard is that pvc is not food grade and will add off flavors. i could be mistaken but would personally use something that i no is food safe. just my 2 cents.

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He states that it is cpvc and that is fine for the temperatures. Pvc tubing is used in drinking water plumbing all the time. But not for high temperatures.

I have a stainless braid from a water heater supply line in my mash tun so I have no experience to lend as to the cpvc manifold.

I've been using an igloo cube with a cpvc manifold I made for about 6 years. Looks similar to your picture, just a little different because my older cube is flat across the whole bottom of the cooler.( I noticed they changed them.) I drilled a bunch of small holes all over it and it works great.

so before I drill the holes or cut the slits in the bottom of the manifold, does it appear "correct" as far as design and distances from walls? I want to avoid channelling as much as possible and don't mind changing the design (as cpvc is cheap and I have plently left over) but I'd like to have it at least close to right when I do AG the first time.

the cpvc looks a little close to the edge but at that size it doesn't matter. Thumbs up.

right now I'm about 1-1/2" from the center of the perimeter tubes on to the wall, how much should I move them inward? Everything is an easy fix at this point

If it helps at all this is what mine looks like.

To avoid channeling, you want the distance the wort has to travel to be the same all over. So if your cross pieces are 1.5 inches apart, you should plan to have your outside pieces 1.5 inches from the walls of the container.

<edit>

They should actually be 1/2 of the crosspiece spacing...

ok, here it is reworked to 2-1/2" from the outside walls and approximately the same distance between the individual rails, better, worse or the same ?

Thank you WesleyS, it does help. How do you have the bottom slotted or drilled? What kind of efficiency are you getting?

I was under the impression that channeling is not an issue unless you are fly sparging? is this true?

mobrewdude said:

Thank you WesleyS, it does help. How do you have the bottom slotted or drilled? What kind of efficiency are you getting?

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The bottom is drilled with 3/32 inch holes all over, fittings included. I get 65% efficiency consistently with the crush from my LHBS. I recently purchased a grain mill to see if I can improve on that.

cyclogenesis said:

I was under the impression that channeling is not an issue unless you are fly sparging? is this true?

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I would guess with batch sparging it should be a non-issue but I am planning to fly sparge so I'm trying to eliminate the obvious problems before I do my first all-grain run.

WesleyS said:

The bottom is drilled with 3/32 inch holes all over, fittings included. I get 65% efficiency consistently with the crush from my LHBS. I recently purchased a grain mill to see if I can improve on that.

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Thank you again, I was planning on the same size holes, I read that was best somewhere along the way. I'll be happy with anything 70% and up and am more interested in consistency than squeezing the last drop of sugar from the grain but I have a sneaking suspicion that it's going to take a good equipment set-up and process to be consistent as well.

Although the geometry of your cooler is not ideal a couple of things can be done to maximize your collection efficiency.

1. Increase the depth of the grain bed. 10 gal batches > 5 gal
2. Slow down the runoff. I run 1qt/min with a false bottom. Since a manifold has less surface area I recommend 1qt/1.5 mins as a starting point.

shelly_belly said:

Although the geometry of your cooler is not ideal a couple of things can be done to maximize your collection efficiency.

1. Increase the depth of the grain bed. 10 gal batches > 5 gal
2. Slow down the runoff. I run 1qt/min with a false bottom. Since a manifold has less surface area I recommend 1qt/1.5 mins as a starting point.

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Thanks for the input. I like the idea of doing a 10 gallon mash instead of a 5, then I can divide the mash into two 5 gallon batches, hop them differently during the boil and/or ferment with different yeasts to to make different beers. I'll take your advice and start with a slow drain/sparge and see how efficiency turns out.

Thanks again!

ok, so does this look about on par as far as holes and placement? Anything else I can do to improve the design?

That looks better. The way it was before would of pinched the flow of the liquid especially in stickier mashes.