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.
To use it:
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).
- 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.
- If you will be bringing the tubing out through the drain hole,
drill the stopper slightly smaller than the diameter of the
tubing (measure to make sure). This is somewhat tricky,
especially with a small stopper. Mark one end of the tubing
about a foot from the end.
- If you do not have a drain hole, then you'll have to bring it
out the top. Mark one end of the tubing about the depth of your
cooler (maybe 10 inches)
- 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.
- 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
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.)
- Now comes the tricky part: bending it to fit. I'm assuming your
drain hole (if you have one) is in the center of one end. You
want to make two right angle (as sharp as you can without
wrecking the tubing) in that end so that the tubing will stick
out a few inches through the drain. On the inside, it should
turn and go to one side of the cooler. Force the drilled
stopper, with the fat end in, over the tubing so that when the
whole thing is put in the cooler, it plugs the drain hole
- Or, if you don't have a drain hole, bend the tubing so that it
stands up to almost the top of the cooler, in one corner.
Boil your wort for at least an hour. Add hops, etc., as usual.
- 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.
- 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.)
- 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.
- 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
- 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.)
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
- With the drain plug version, place the end of the drain hose in
a pot and loosen the clamp until you get a slow steady flow.
- With the other version, attach your siphon hose to one end, and
start the siphon. A hose clamp is useful here, too, to control
flow rate. Keep it below the bottom of the cooler to maintain
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
Top view of manifold (drain plug version):
key: "=" tubing "/","\" bends "I" tubing "O" tubing coming up
"|","-","+" cooler walls
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