Copper Manifold in a Rectangular Cooler

(Metric note: 1" (inch) is 2.54 cm, 3/8" is about 1cm. 1' (foot) is 30.5cm)

Ok, here's a sketch of the procedure. I've used this with a rectangular (30qt) picnic cooler.

  1. Look at your cooler. Does it have a drain hole? If so, you need to get a stopper that will fit it. I'm assuming here that the drain hole has a removable stopper, not a valve of some sort. If it's the latter, you may need to remove the valve (usually by unscrewing a large nut on the inside).
  2. Buy a 10' coil 3/8" tubing (outside diameter, frequently sold as a hook-up for automatic ice makers). 1/4" tubing might work, too. You should also get a "tubing bender" the same size. This is simply a tightly coiled spring with a flare at one end. You slide it over the tubing to the place where you want to make the bend, and bend the tubing inside it. It prevents the tubing from crimping as you bend. Should cost a few bucks.
  3. Measure about (3*L) + W, where L is the inside length and W is the inside width of your cooler, on the tubing from your first mark. Make a mark. Then measure the depth of the cooler from this mark and cut the tubing.
  4. Between the two marks, starting a couple of inches in from the first, and ending a couple of inches from the second (this leaves solid tube for sharp bends), cut a slot across the tubing, about 1/2 way through, with a hacksaw. I built a "jig" to do this by drilling a 3/8" hole in a piece of scrap lumber, and clamping that in my vise. I could then cut a slot, slide the tubing, cut a slot, etc. I used a carbide hacksaw blade; it makes somewhat wider cuts than the regular kind. This may or may not be good (but it works for me.)
  5. IMPORTANT: Make sure to make your bends so that the slots end up facing down. Then you run the tubing the length of the cooler along the side, bend it in a U back to the other end down the middle, another U takes it back to the far end along the other side. My current manifold runs very close to the cooler walls and works fine. Then, bend the tubing up so it runs almost to the top of the cooler (you may need to trim the end at this point.)
To use it:
  1. Put the sparge manifold into the cooler (with the stopper blocking the drain hole, if you've made that version). Attach a length of tubing to the "drain" end, and close it with a tubing clamp (the kind with a thumbscrew works best, and will let you easily regulate the flow when sparging). If you don't have a drain plug version, don't attach the tubing yet.
  2. Put your grain into the cooler. Heat your mash water to 170F (allow about 1 quart per lb of malt). (If you're making a 3 gallon batch, you might use 6 lbs of malt and 1.5 gallons of water.)
  3. Place one end of a siphon hose into the mash water, and start the siphon. Pinch or clamp near the end of the hose, and push the end over the top of the copper tubing coming up in one corner of your cooler. Stir to thoroughly mix the water into the grain. You should end up with a temperature between 150 and 160F.
  4. Take off the siphon hose, and put the lid on the cooler. Let it sit and mash for an hour. (If you're the worrier type, you can try doing an iodine test, but it's probably not worth it, and mine always come out black when I do it from the top of the mash anyway.)
  5. Heat about 1/2 the original mash water quantity to boiling, and siphon (or pour) it into the mash to raise the temperature to 170F. It's helpful to measure while you're doing this so you don't overshoot too much (this is one step I don't have well calibrated, yet). I find that running the water in through the manifold gives me more even temperature distribution (i.e., better mixing) than pouring it in the top. Let this sit at least 10 minutes while you heat more water to 170F (I actually do this in stages while I'm sparging -- heat a gallon, add it, heat another gallon, etc. How much you really need depends on a lot of factors, but it won't exceed your total target volume, anyway.)
  6. Now, you're ready to sparge. (Keep an eye on it, if you start getting bubbles in the tubing, you need to slow down.) Take the first few quarts and pour them (gently) back into the cooler. The outflow should be pretty clear by that point. I put a bowl into the middle of the grain bed and pour into it, to avoid disturbing the grains. Add sparge (170F) water as necessary to keep the level of water in the cooler above the top of the grain bed. You stop sparging when any of the following conditions are met: 1. You've got as much as you can safely boil in your pot (hint: if you've got enough pots, start the first bit boiling while you're still sparging). 2. The specific gravity (corrected for temperature) falls to 1.010 (this means about 0.995 at 150F). 3. The outflow starts to taste like weak tea (somewhat astringent).
Boil your wort for at least an hour. Add hops, etc., as usual.

It's useful to figure your "extraction rate" so that you'll be able to better calculate how much grain you need to make a specific strength beer. To do this: Measure the specific gravity of your final wort (call it OG). If the volume of the wort is V, and you used L pounds of malt (not counting dark grains, and crystal malts need to be discounted by multiplying by roughly 80%), then your extraction is

E = (OG-1)*1000 * V / L (points/lb/gal)
Thus, a wort of 1.050 in 3 gallons starting with 6 lbs of grain has an extraction rate of
(1.050 - 1) * 1000 * 3 / 6 = 50 / 2 = 25 pts/lb/gal
That is to say, you got 25 "points" of extract from each pound of grain (for a total of 150 points), diluted into 3 gallons gives 50 points or 1.050 total. 25 is not bad, 30 is pretty good, anything over 30 is excellent. Your first time, I wouldn't shoot for anything over 25. If you get more, you can always dilute the wort after boiling it (with boiled, cooled water, of course).

Well, this came out longer than I expected. I'll conclude with a picture.

Top view of manifold (drain plug version):

key: "=" tubing  "/","\" bends  "I" tubing   "O" tubing coming up
     "|","-","+" cooler walls

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