Three Keg Brewing System Description

Disclaimer

The following is a high-level description of a specific three-keg beer brewing system I recently built for my use in making 10-13 gallon batches of the frothy nectar. The design is based on my own understanding of the all-grain, small-batch brewing process, on the visual inspection of a Pico Brewing System (Pico Brewing Systems, Inc., Ypsilanti MI, 313-482-8565), on inspection of the three-keg, gravity fed system offerred by Brewer's Warehouse, Seattle WA (206-527-5047), and on inspection of several photos of the Brew Magic system (800-321-BREW). I make no claim to the worthiness of my design for any particular purpose, nor do I claim to have used the best materials available. The following is an accurate description of what I DID build, along with comments regarding how you can do better. Finally, I make no claim that the system I built is as good as or better than any of the systems previously mentioned, nor that my system would cost you less to build than to buy. Whew!

Process

1. I first drew a diagram of what the system should look like. I started with the idea that there would be three Sanke beer kegs mounted side-by-side on a metal support frame, with that same frame supporting two pumps and three natural gas burners. I wanted the top rim of the kegs to be at a convenient height, which I decided to be about 48" off the floor.
2. The supporting frame is an aluminum truss design about 6 feet long and 22" from front to back at the bottom, and about 17" front to back at the top. The top of the frame is about 24" high. I used pieces of steel bed frame stock bolted across the top of the frame to act as spreaders for the frame itself, and also to prevent lateral motion of the kegs. Each keg sits on top of the frame between two of these angle-iron rails. A faxed sketch would use much less bandwidth than my continued attempt to provide a good description.
3. Initially I used three salvaged water heater burners mounted about 3" below each keg, and piped each burner to a gas manifold leading from a single salvaged water heater regulator. These burners don't come close to the BTU output needed (they're about 35 kBTU) and were replaced after the first batch. I built the replacement burners from black steel gas pipe fittings available at the local Home Depot-type store. The main burner component is a 2" NPT nipple 6" long, through which I drilled a transverse hole large enough to get a section of 3/8" NPT black pipe. Basically, I cap one end of the 3/8" pipe, and feed gas into the other end. Through one side of the 3/8" pipe I drilled a single gas orifice hole (coaxial with and aimed along the axis of the big 2"" NPT nipple). I wrote down the hole size for natural gas, but haven't built one for propane. These burners will be modified in the next month or so for propane, however, so I'll know the proper orifice size at that time. As currently configured, these burners produce a 2" diameter flame about 18" tall--work like a charm. Because the burners aren't aligned perfectly with the axis of symmetry of the kegs, they fire off-center creating some handsome convection currents in the kettle. The agitation added by this asymmetry is beautiful to behold--just like the big boys!
4. My brewing associate purchased two food-grade pumps we found in an industrial catalog which use an isolated magnetic drive system to drive a simple plastic paddle-wheel--about the most primitive pump you can imagine. These pumps were designed for pumping fruit juices and similar materials expected to contain pulp (re: hops, barley grains, etc). They can be taken apart without tools (stainless steel wing-nuts) and completely sanitized. They connect to any hose having a 5/8" ID--we're using clear vinyl tubing until we can find something that stands up to the temperatures a little better. These pumps are not self priming, so they must be mounted below the kegs (not UNDERNEATH the kegs, necessarily) to ensure a gravity start--but, they do pump to an 11 foot head, and CFM is way up there. These pumps were $80 each through a local industrial supply house that was willing to sell retail at wholesale prices.
5. Back to the kegs. This is the hard part. Although beer kegs don't have the best shape for heating, cleaning, whirlpooling or anything else, they ARE stainless steel. My opinion is that stainless is the only material to bother with here--aluminum is definitely out, and you won't find copper if you live in the US. Finding kegs is a big problem, but I live about an hour from Coors, which sells non-Coors kegs which get erroneously brought in to their plant. They sell non-Coors kegs only for $15 each, and only get a few a month. You DO get an official Coors letterhead receipt for the kegs--we now have a Bud keg, a Sierra Nevada keg, a Becks keg, and a Labatts unit. The Labatts keg was absolutely virgin--it appeared to be uncirculated--we use it for our conditioning/dispensing keg.
6. Okay, so after acquiring the kegs, of course, they have to be opened up. I took a pistol drill and a small high-grade drill bit and spent about 40 minutes per keg, drilling about 200 holes along a scribed 10" circle on the top end of each of the three kegs. AFter knocking out the disk, I then used a big 4" belt-sander to go in and grind up to the line. If you're handy with power tools, this can be done to look good--if you are concerned about aesthetics (how could you NOT be?), this will take about 30 min per keg.
7. If you have a factory outlet mall nearby or can find a factory outlet for kitchen ware, or have a good hardware store, you can get 10" saucepan lids to fit these holes nicely. Don't bother. With the big burners, you'll be too busy to cover any of the pots.
8. Next, we found an industrial supply place in town that happened to handle stainless steel pipe fittings (good luck). We bought two standard 1/2" NPT nipples in SS, and used a hacksaw to saw each of them in half laterally. This gave us three short nipples, which we then took along with the three kegs to a welder, who welded them through the side of each keg near the bottom. There are good welders, and there are ok welders. When I was 17 I could weld better blindfolded than this guy, but he charged 'only' $25 for the whole job--others in town wanted $15 per keg.
9. Into each of the nipples just described, I fit a 1/2" brass ball valve. These were about $5 at your neighborhood plumbing shop, and have SS balls in them and are easy to clean. Now, visualize...three equally spaced kegs sitting on top of a support frame, each having a ball valve on the side near the bottom to control flow from the keg. Sparge tank on the left, mashtun in the center, and kettle on your right. About 12" below the level of the bottom of the kegs, I mounted the two pumps--one pump spaced between the sparge and mash tanks, the other pump spaced between the mash tun and kettle.
10. I have a hose running from the sparge tank into the inlet of the left pump. The outlet of this pump feeds into another ball valve, which in turn has a 5 foot piece of flexible hose attached to it. I can therefore direct the sparge water back into the sparge tank (just to recirculate it for temperature control), or I can drop the hose into the mash tun during sparge. I don't use a spray head on this hose--I just close down the ball valve on the outlet side of the pump to control for a gentle flow onto the grain bed.
11. Off the ball valves on the mash tun and the kettle, I've run a tube down to a tee on the second (rightmost) pump inlet. The pump outlet on this pump is set up just like the left pump--a ball valve for control followed by a 5 foot section of flexible hose. This configuration allows us to recirculate the mash liquor during mashing--to ensure a nice distribution of temperature in the mash tun, and to establish a handsome grain bed. It also allows us to pump from the mash tun into the kettle after mash-out. Likewise, the bitter wort from the kettle can be pumped out into the fermenter...
12. What we actually do just prior to kettle-out is as follows: at about 30 minutes prior to kettle-out, we start sanitizing the sparge tank (which we've emptied) and the sparge pump (the leftmost pump) and associated tubing. I just recirculate a sanitizer through the hoses, pump, and sparge tank for about 30 minutes. When the kettle is ready to empty, we flush the sparge tank, rinse it, then pump from the kettle back into the sparge tank. Since we're pumping from underneath the screen in the kettle, the hops stay put. We have yet to try a whirlpool to precipitate trub, but it probably would be of little value due to the suboptimal shape of a beer keg (too prolate). At this point we have fairly clean hot bitter wort in our sparge tank, which is a 13 gal Euro style tank--a little shorter our Sanke kegs. I also have a larger hole in the sparge tank, and these factors make it easy to get our big TurboCool immersion cooler into action. TurboCool is a 50 foot dual concentric coil of 3/8" soft copper line--with winter water supply temps we can cool the 12 gallons of wort in about 12 minutes.
13. Screens. Ooh baby. I said earlier to use SS whenever possible, and I still say it. But when it came to screens, the community was not too helpful. You can buy copper ones from Pico for about $45 each, or get raw SS pre-drilled stock (square) from some mailorder places for about $50 each. You then have to figure out how to get them into the kegs-- remember the hole in the top of each keg can't be much more than 11 or 12 inches, and mine are 10". The screen has to be in two pieces, then either assembled inside the keg or unfolded in some way. Good luck finding SS. I was at K-Mart one day and found a 17" aluminum pizza pan pre-drilled (for cooling) with about 900 holes. The size and spacing of the holes was very close to the specs given to me for the stainless stock I was told about. Using a band saw, I cut around the perimeter of each of these "screens" then cleaned up with the belt-sander (my favorite tool), until I had the proper diameter. I then used a thin blade on the band saw to cut each pan in half along a diameter. Very nice job, I might say. Total cost was $8.50 each. Each half is then bolted to a SS strap of 1" wide by 1/8" thick, using SS machine screws. This has to be assembled after you get the two pieces inside the tank. Kind of cumbersome, but we don't do this everyday!
14. Now for the good part. As you'd expect, we didn't know how sparging would go with these screens. Holes too big? Holes too far apart? Will it stick, will the grain just fall through? Well, we lucked out. Sparging is a brewer's dream with these pizza pan filters! You can pump out mash nearly as fast as you want, even let the grain bed go dry, and still the water flows. What's more, after only about 2 minutes of recirc, the goo flows clear--the grain bed is established quickly and few if any grains continue to flow through the screen. Brought a tear to my eye. As long as you pull the screens and rinse them well after you've finished the session, staining of the aluminum is minimal--and it is actually probably benficial to allow staining since this will continue to reduce the acidic attack on the material as time goes on. I did find stainless pizza pans identical to the aluminum ones at a Denver restaurant supply, and they are $35 each. Will "migrate" to this tech when in the mood.

Notes:

Secondly, the screens work perfectly, but should simply fold open inside the tanks rather than require screw-together assembly. They should also be SS, not aluminum.

Thirdly, in the ideal world the kettle would be more oblate--proportioned more like a tuna can than a soup can. If it were, then the hose coming off the rightmost pump could be used and a tangential injector (just like the big boys), and one could spin the crap out of the wort at kettle-out and have some expectation of packing trub up in the center of the kettle screen. Combining this mechanical action with a little Irish Moss, and your friends would be astounded at gunk left in the kettle, and left out of the fermenter.

Finally, after having put myself through this living nightmare of fabrication and testing, here's what you should REALLY do...find two or three other good, like-minded friends, and split the cost of a pre-built $2000 system. I guarantee you'll spend LESS money, and have more time to develop your technique with the gear. You can do better than the Pico System, but probably not as good as the Brew Magic system, IMHO.