I originally posted this in my5 Gallon MLT W/Copper Manifold thread but thought I would give it it's own spot for easy searching. I found a design that used non standard pipe sizes and converted it to copper. I have found a lot of people looking for plans for one so I thought I would share.
This design was meant for a cooler style MLT so you may have to adjust size of arms and how you would mount it.
Sparge Arm Parts list:
1) Can o' Foam
1) 1/4" Copper T
2) 1/4" Copper End Caps
2) 1/4" x 4 1/4" Soft Copper
1) 1/4" x 3 1/2" Soft Copper
1) 3/8" x 2 1/2" Soft Copper
1) 1/2" x 6" Copper
3) Super Small Supper Skinny O-rings
First take the 1/4 x 3 1/2 piece of soft copper, straighten it and flare one side. Usually you can ask someone in a plumbing store do do it for you. I do it for people all the time.
Next, slide the 3/8 x 2 1/2 over the the flared piece. You may have to ream out the 3/8 piece to create a smooth action between it and the flare.
Now attach the 1/4 T and sweat it on. Also if you can't do this there might be someone you can ask.
You should en up with something like this.
Next take the O-rings and put them onto the 3/8 piece and slide that into the 1/2 x 6 piece.
Now take the 2) 1/4 x 4 1/4 pieces and, using a nail, tap starting points to drill holes in. Drill holes.
Sweat on the 1/4 caps to your newly drilled arms. It might be nice not to use the caps at all and just pinch them shut. It would be one less place to clean flux from. Then sweat those into your 1/4 T with the holes facing one or opposite directions (depending on your perspective) to push the arms.
Test your sparge arm, it should spin off of a basic gravity feed.
Attaching to MLT:
This is the part I'm working on still so these are still in the works. I'll edit this with the final plan once I'm done..... so, theoretically....
Now you have to drill a 1/2 hole through the center of the lid. This is a good time to spay foam into the empty space in your lid. QUICKLY slide your sparge arm through the lid before it can really expand. Clean off the excess.
Now slide a Washer with a 1/2 ID over the top of the 1/2 copper sticking out. Then put on a thick O-Ring the copper to hold it from falling through the lid.
After that you'll have to adjust to fit to your HLT. You can sweat a 1/2 Male Adapter or barb, etc. That part is up to you.
Thanks. Oh, that's what you were talking about: laying the tubing on the mash. That seems less efficient to me compared to uniformly distributing the sparge water over the surface of the grain like a sprinkler system. What do you think?