A Simple Recirculating Wort Processor

Kirk R Fleming / Colorado Springs / flemingk@usa.net

Original: 1 January 1995
Last Rev: 14 April March 1995

Introduction and Acknowledgements

This is a description of a three-keg beer brewing system built to make 5 to 15 gallon batches of the frothy nectar. The design is based on:

While this sytem lacks automated feedback control, it is relatively easy to build and use. Among its positive features: convenient access to all system components while brewing, continuous recirculation and temperature readout during the mash, extremely easy and "forgiving" sparging, and burner output adequate for very vigorous boiling of a full 1/2 bbl kettle. It provides a platform to accomodate future improvements as time, money, experience and knowledge permit.

Special thanks to Mr Kenneth A Kladitis who purchased most of the materials for the project, assisted with assembly and offered many amusing observations. Thanks also to Mr Mike Bristol of Bristol Brewing Company of Colorado Springs, and to his most helpful brewer Jason. Both took considerable time from their hectic schedules to review my plans and provide constructive criticism. Thanks to Mr Mark Stevens for posting this file and making it available to interested brewers.

Abbreviations Used

Initial Design Goals

There were two main design goals for this system: 1) the ability to brew 5-15 gallon all-grain batches with adequate mash tub capacity to avoid mishaps and messes, and 2) the ability to conduct the brew without having to move any liquid-filled vessels. I also wanted to pump from the mash tun into the kettle while pumping from the sparge tank, and so the design assumed the use of two pumps. It was not built with any loftier goals such as extreme control of mashing temperatures, high extraction efficiency, or hands-off operation. However, the only inherent aspect of the system that might preclude achieving these goals is the use of Sankey kegs, due to their suboptimal shape.

I drew several diagrams of what the system should look like, starting with three Sankey beer kegs mounted side-by-side on a metal frame supporting two pumps and three natural gas burners. I wanted the top rim of the kegs to be about 48" off the floor. Tank and frame designs all assumed the use of materials I already knew I could obtain, and were iterated as new materials were found. The entire system design eventually revolved somewhat around the available pumps which met sanitation, capacity, temperature and cost constraints, and around a desire to minimize welding. More on the pumps later.

The Support Frame

The supporting frame is an aluminum truss design built mostly from drawn aluminum angle stock and aluminum bar stock obtained from a local scrap dealer at $2 per lb. The frame is 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 bedframe 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. In addition, two 7" pieces of rail are mounted at the front and back of the frame in front of and behind each keg. The keg therefore sits in a short "cage" which prevents any lateral motion during the brew. The entire unit is mounted on four heavy-duty casters, and the frame is blocked up and leveled prior to use.

The Burners

I first 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 didn't come close to the BTU output needed (they're about 35 kBTU) and were replaced after the first batch. Total cost of that error was about $65 in brass gas cocks and aluminum gas tubing.

NOTE: In his discussion of a brew system design in the Jan/Feb issue of Brewing Techniques, Mr Jim Busch says a 35,000 BTU burner should be sufficient to heat 19 gal of water to a vigorous boil. This doesn't agree with my results, but that doesn't mean Jim is wrong! For reasons related to pressure and air mixing, my water heater burners produced a very soft, rolling blue flame--not efficient as installed. I felt an order of magnitude more energy was the only goal worthy of a design change, and the easiest way for me to solve the problem was to simply replace the burners.

The replacement burners are from black gas pipe fittings available at the local plumbing shop. The main burner component is a 2" NPT nipple 6" long. About 1 1/2" from one end I drilled a transverse hole large enough to slip through a section of 3/8" NPT black pipe. One end of the 3/8" pipe is capped and gas in fed into the other end. The 3/8" pipe is drilled with a single gas orifice (coaxial with and aimed along the axis of the big 2" NPT nipple). I started with a very small hole, then by trial and error continued to enlarge it until the resulting flame started at the mouth of the 2" nipple. These burners could be modified for propane by simply replacing the 3/8" pipe with one having a smaller orifice.

The burners produce a 2 1/2" diameter flame about 18" tall--work like a charm. Because the kettle burner isn't aligned perfectly with the axis of symmetry of the kettle, it fires off-center creating good convection current. The agitation added by this asymmetry is beautiful to behold.

The Tanks

Although beer kegs don't have the best shape for heating, cleaning, or whirlpooling, they ARE stainless steel. My opinion is stainless is the only material to bother with here. Finding kegs can be a big problem, but we now have two Sankey kegs and a Becks keg (which is a 50L Eurostyle that looks like a short Sankey). Our luck was good, and these kegs are in nearly unused condition.

Jim Busch offers guidance on acquiring kegs in the Jan/Feb 95 issue of Brewing Techniques. If you want to minimize fuss and schedule delay, sources such as Sabco will ship you a ready-to-use product. If you want a good looking, efficient setup and don't mind spending considerably more money, outfits such as Precision Brewing Systems will sell 15 and 20 gal stainless stock pots, and will customize them to order with thermometers, spigots, and sight glasses. You may find other sources that will do the same.

The kegs have to be opened up, and there are many articles elsewhere on how to do this using SawzAll-type saws. I used a pistol drill and a small high-grade drill bit and spent 40 minutes per keg drilling ~200 holes along a scribed 10" circle on the top end of each of the three kegs. I then used a hacksaw blade (the best I could find) to cut the webs left between the holes. Others have recommended drilling larger holes so you have to do fewer of them--I feel that it's easier to drill smaller holes, more of them, and be left with less material to grind out.

After knocking out the disk, I 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 this will take about 30 min per keg. Be careful: the sheet metal is very sharp and you'll be sorry if you get slack! This method sure is primitive, but it's an alternative to the cost of Sawz-All blades (and to getting a saw). I only had to use two drill bits for all three kegs, and they can be resharpened. See Lesson Learned below.

We bought two standard 1/2" NPT couplings in stainless steel from a local supply house, and used a hacksaw to cut each of them in half laterally. We took three of the four half-couplings along with the three kegs to a welder for assembly.

Lesson Learned

When you take the kegs to the welder, also take along a straight, threaded section of steel pipe that can be screwed into the coupling when the coupling is welded into the keg. The pipe indicates the coupling's orientation (square and level). I also recommend you select a welder specializing in stainless who can also cut the tops out of the kegs (you provide a template). Skip the agony of removing the tops yourself, if possible.

More on Plumbing

Throughout the design I've tried to ensure wort flow doesn't encounter sharp shoulders, inclusions, tight turns, etc. This is with a view toward cleaning, not due to a fetish with smooth flow or pressure losses. I specifically wanted to have a single smooth tube carrying wort from the bottom of the mash tank (and kettle) out through the side of the kegs to the spigot shutoff valves. To do this, I purchased two 3" long 1/2" NPT brass pipe nipples at the hardware store. I have no idea what they are normally used for. I cut them each with the hacksaw to provide a short nipple having a threaded section and about 3/4" of unthreaded section.

For each tank I then cut a section of 1/2" rigid copper pipe long enough to reach inside the keg about 4 inches, and at the same time protrude about 1" through the welded stainless couplings to the outside of the tank. One brass nipple section was then pushed up over one end of each of these copper pipes and soldered on, leaving about 1/2" of copper protruding out from the non-threaded end of the nipple. When the brass nipple is threaded into the stainless coupling on the tank, the copper pipe then extends into the tank about 4".

Finally, on the end of the copper tube which extends into the tank I soldered a 45 degree "el" and another short section of copper pipe. This last piece of copper pipe is the dip tube or collector, and extends down into the little pocket in the center bottom of the keg. By trimming off this pipe at a 45 degree angle and adjusting its length, all but about 50mL of liquid can be scavenged from the bottom of the mash tank. This arrangement ensures a conveyance for the wort that is internally smooth and which can be cleaned throughout its length with the kind of brush used for musical instruments.

All three tanks have this same internal plumbing configuration, and although it's great for the mash tank, it's less than ideal for the kettle. The dip tube in the kettle pulls wort from the most highly trub-concentrated part of the keg--dead center in the lowest pocket. Likewise, if we use the sparge tank as a second boiler for doing full 1/2 bbl batches, the same situation exists. An easy and recommended design modification is to shorten these tubes for sparge and kettle, and accept the losses.

The 1/2" or so of copper tubing that protrudes to the outside of the tanks can be used to solder on ball valves, elbows, or whatever else you want to solder on to the tank. On the kettle and sparge tank I just soldered on a copper elbow followed by a standard 1/2" sweat ball valve. For the mash tun, the first fitting attached was the threaded bronze portion of a standard 1/2" sweat union. This was designed to mate up to my thermometer and ball valve assembly (see below).

Lesson Learned

Have the coupling welded to the keg so it's flush with the inside of the keg and thread the brass nipple in from the inside of the keg. This way the annular pocket between the inside of the stainless coupling and the copper tubing is on the outside of the keg, where it doesn't collect goo. Goo is bad--goo is the enemy. Also, by leaving the stainless coupling intact instead of cutting in half, then there would be a threaded portion of it on the outside of the keg as well. Then, another short brass or steel nipple could be slipped up over the copper tube on the outside of the keg and threaded into the coupling for extra support of the copper tubing. The outer sleeve would, of course, not be soldered to the tube.

The Thermometer Assembly

Recently added to the wort processor after extreme frustration with getting good mash temperature readings is a 3" dial-type bi-metal thermometer. From the previous paragraph note I soldered the threaded bronze half of a union to the copper pipe extending from the mash tank. This is the piece of a union having a polished, concave ring of brass or bronze which in use will be drawn up via a ring nut onto a matching copper male ferrule. The assembly was made as follows:

Create a mental picture of a copper "T" oriented in space like the letter "T". I soldered a short (3/4") piece of copper tubing into the bottom inlet of this "T". The bronze union ring nut was then placed up over this short tube, then the male copper ferrule soldered on. After this assembly the ring nut is captive (it's purpose is to bear on the ferrule shoulder, and draw it into the bronze concave part presently installed at the keg).

Into the "T" outlet pointed to your left I soldered on a 1/2" copper to 1/2" NPT (female) fitting, again using a short piece of copper tube to provide the interface. The dial thermometer is built with a stainless steel 1/2" NPT male thread which of course fits down into this copper fitting. The "T" outlet pointing to your right just solders up to a ball valve. By using liberal amounts of elbow grease and abrasive pads, this entire assembly was thoroughly cleaned up, then the thermometer threads prepped with Teflon tape and threaded into the threaded copper coupling.

I mated up the assembly to the keg with a slurry of extra fine lapping compound on the union. As they come from the factory, these fittings won't hold household water pressure unless the ring nut is tightened down with a pipe wrench and brute force. The seal is formed by the slight upsetting of the male copper ferrule into the concave brass piece. I didn't want to have to use a wrench for assembly/disassembly, so I put the two pieces together with a slurry of lapping compound. By repeatedly rotating the two and intermittently tightening the ring nut by hand, the interface was improved to a lapped, perfectly mating surface. The unit is now leak-free with just hand assembly.

When assembled for use, the inlet to the "T" mates up to the keg, and the thermometer face is horizontal, facing up. The ball valve empties vertically downward toward the floor, and is connected with a short piece of silicone tubing to the pump inlet.

Kettle Sight Glass Assembly

We experienced some inconvenience and inaccuracies in determining boil volumes during the first 5 brews using this system. Batch 5 was a particular problem for some reason, where we mis-read the final volume by over 1 1/2 gallons, reducing too far. We had a target gravity of about 80 and finished with 92 instead. This was the last straw. An accurate sight glass was needed.

Based on a recommendation posted by Mr Jim Hunter in the March 1995 HBD #1672, I opted to tap into the brass fitting currently threaded into the SS coupling on the side of the kettle. This fitting is a 1/2" NPT pipe nipple, but made of brass. Just outside the SS keg coupling I drilled an 11/32" hole into the brass pipe, tapped it (1/8" NPT) and screwed in the Teflon-wrapped, brass barb.

From the local hardware store I obtained a 3' section of 1/2" diameter rigid drawn aluminum tube, and cut it to 16" length. I placed this tubing in a vice on the workbench horizontally in such a way as to leave half the pipe exposed above the vice jaws. I cut the front half of the pipe away from end-to-end using a standard hacksaw (32 teeth-per-inch). The rough edges were then filed smooth and straightened with a standard mill file.

The sight tube is a 16" piece of 1/4" inside diameter polyethylene tubing used for icemaker water feed and other potable water applications. This tubing was warmed up at one end and pushed down over the hose barb now installed on the keg, and the aluminum support tubing slid down over the polyethylene tube. Once in place, the top end of the aluminum support tube was supported with a short piece of 1" wide by 1/8" thick aluminum strap, screwed to the keg chine with a sheet metal screw. The strap has a 1/2" hole in one end that slips over the aluminum support pipe. The back end of this strap (toward the keg) has the last 1" bent upward at a 90 degree angle, providing the surface through which to screw the sheet metal fastener.

After installation and leak-check, we "calibrated" a 1/2 gallon jug and used it to fill the keg with 1/2 gallon increments of water. At each increment I placed a mark on the aluminum support pipe using an indelible marker (we were in a hurry to brew, man!). We then bounced these readings against several other graduated vessels lying around, and found the accuracy acceptable. We can now assure stoichiometrically correct brew volumes :). Stability of the reading during a full boil is good enough for estimation, and for more accurate reads we just shut off the kettle burner momentarily. Total cost for this sight glass was about $8.

The Pumps

I use two food-grade Teel pumps (WW Grainger catalog #1P677). The pumps were a compromise between capacity, chemical resistance, thermal specs, and cost. The pump selected is a magnetic drive unit with isolated polycarbonate impeller and impeller housing. This model runs off 115VAC, pumps 7.2 GPM at 1ft head, and is rated to 180F. The 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, and connect to any hose having a 5/8" ID.

I felt the short duty cycle of the kettle pump and the pump safety factor rating would allow me to use it for pumping the boiling wort with no problems. Of course, for typical mash temperatures this rating is adequate. The pumps are guaranteed to work well for liquids in the pH range of 5-9, and again I felt since this was the continuous-operation range guaranteed, if we ever saw wort below 5 it would be limited and safe for the pump. I also felt if we had wort with a pH less than 5 we would be having other, more serious problems.

A 15" section of hose connects the sparge tank outlet to the inlet of the left pump. Another short section of hose connects the pump outlet to a ball valve, which in turn is attached to a 7 foot hose. The 7' hose is used to direct the sparge water back into the sparge tank to recirculate it for temperature control, and into the mash tun during sparge. I don't use a spray head on this hose--I use the sparge pump outlet valve to control flow into a small copper manifold that distributes the flow to four outlets. When viewed from directly overhead, the copper manifold looks like the capital letter "H". From this view the inlet into the manifold is a short piece of 1/2" copper tubing coming out of the page at the very center of the "H". At each outlet (the legs of the "H") I've added a 1/2" copper "T", providing 8 1/2" outlets for maximum flow. In addition, at each point on this manifold where fluid makes a 90 degree turn I've drilled a 7/32" hole through the fittings. Thanks to Dion Hollenbeck for his inspiration here.

The mash tun and the kettle drain valves are each connected with 15" hoses to a tee fitting on the second (rightmost) pump inlet. The pump outlet on this pump is set up like the left pump outlet just described--a ball valve for control followed by a 7' hose. This configuration allows mash recirculation to ensure a nice distribution of temperature in the mash tun and to establish the grain/filter bed. At mash out we shut off the recirc valve (on the pump outlet), remove the manifold from the end of the hose, and place the hose into the kettle. We then open the valve and pump from the mash tun to fill the kettle. Likewise, the bitter wort from the kettle can be pumped out into the fermenter.

The pumps are mounted about 12" below the level of the bottom of the kegs. One pump is spaced between the sparge and mash tanks, the other pump is between the mash tub and kettle. The pumps are mounted on rails that run from front to back on the frame. These support rails are in turn supported by two rails that run horizontally along the length of the frame--one of the front and one at the back, both of which are about midway between the floor and the top of the frame. At this point the system is comprised of three equally spaced kegs sitting on top of a support frame, each having a ball valve on the front near the bottom to control flow from the keg. Sparge tank on the left, mash tub in the center, and kettle on the right.

The Screens (Prototype I)

I was unbale to find any affordable stainless steel material from which to make screens for the mash tun and kettle. You can buy slotted copper ones from Pico for about $45 each, or get square sheets of pre-drilled stock from some mailorder places for about $50 each. With the latter, you 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.

One day at K-Mart I found 17" aluminum pizza pans 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" along a scribed 15 3/8" circle, then cleaned up with the belt sander. If carefully done, you can get a very nice fit for the kegs, with no space for grain or hop bypass around the perimeter.

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. Each half is then bolted to a SS strap of 1" wide by 1/8" thick, using SS machine screws. The strap is about 4" longer than the keg diameter and centered on the screen. Each end is bent down at 90 degrees, to provide a support foot to hold the screen above the keg bottom. A second strap identical to the one just described is bolted at its center to the other strap and oriented at right angles to it. This provides four feet to support the screen. This all must be assembled after you get the pieces inside the tank, and is a bit cumbersome, but we don't do this everyday! Total cost: about $10.00 each.

Two issues. First, the use of aluminum in this application is not very attractive to most folks, and of course stainless is preferred. However, based on a number of magazine articles and comments from Homebrew Digest contributors, aluminum in this application doesn't pose any health threat, nor does it seem to contribute taste. If you pull the screens and rinse them well after the brew, staining of the aluminum is minimal--and it may be beneficial to allow staining since this will continue to reduce the acidic attack on the material as time goes on. For some discussion of aluminum in the home brewery, see the Jan/Feb 95 issue of Brewing Techniques. I've found stainless pizza pans identical to the aluminum ones at a restaurant supply for about $35 each, but they have no holes (more work). Second, these particular pans aren't drilled out to the pan perimeter. The hole pattern ends about 2 1/2" or more from the edge of the pan. This has been no problem for us at all, but flow through the grain bed might be improved by extending the hole pattern. I doubt the result would be measurable, however.

Lesson Learned

The screens described above worked well for Brews #1 through #4. On Brew #5 the mash tun screen buckled under the load of about 22 lbs of grain. This collapse was not a total disaster, but did allow a lot of grain to flow past the screen and into the pump. The Teel pump handled the challenge well, but did need to be repeatedly shut off and restarted in order to clear the debris.

For Brew #6, we removed the remaining screen from the kettle and used hop bags without the screen. The kettle screen was used in the mash tank, where it collapsed under a 20 lb grain bill. Why we did this is really quite beyond me...but the results were about the same as in Brew #4. We were able to establish a nice grain bed, but it took very gentle recirculation and of course no mash stirring.

For $23 we picked up two 1/8" thick aluminum plates about 15" x 25", which we will cut into 15" disks with the band saw and perforate with about 900-1000 holes, 5/64" diameter on 1/4" centers. The work involved is substantial, but at one hour per evening it shouldn't be too overwhelming a task, and the savings over stainless stock can be put into grain (or food for the children). See The Screen (Prototype II) below for details.

The Screen (Prototype II)

The previous section dealt with how the mash and kettle screens were built in the initial design, and the Lesson Learned section following it discusses the problems encountered with that design.

As mentioned in the Lesson Learned section above, we picked up two aluminum plates (1/8" thick) from which to build replacements. I decided to just build one for the mash/lauter tank, retaining the use of hop bags in the kettle. The current plan is to build a large stainless steel, two-piece clam-shell strainer basket for the hops, and eliminate the use of a false bottom for the kettle entirely.

I took one of the aluminum plates and drilled a 3/16" hole in its center. I also cut a 7" long piece of 1" wide by 1/8" thick aluminum strip, and drilled a 3/16" hole through it near one end. At the other end of this strip, 7 3/8" away (on centers) I drilled a second 1/8" diameter hole. This strip was then bolted with a machine screw to the aluminum plate, and used as a trammel (compass) to scribe a 14 3/4" circle on the plate. The disk was cut out using a metal-cutting blade installed in a Delta 16" band saw. The belt sander was pressed into service again to grind the edge of the plate up to the scribed line.

To drill the holes into the aluminum plate, I built a simple template from a strap of 1 1/4" wide by 1/8" thick steel stock obtained from the local building supply store. I scribed two parallel lines on the strap from end to end and 1/4" apart. On one line I center-punched every 1/2", and on the adjacent line I did the same, but started the marks 1/4" further down the steel strap. These punch marks were then drilled using a 5/64" bit, leaving a pattern of two staggered rows of holes. This template was then aligned with a diameter of the aluminum plate, and used as a jig for drilling through the plate. After drilling one hole at each end of the template, I held the template in place by dropping two nails through both the template and the aluminum disk. Then, the rest of the holes were drilled. After completing one pass, the template was moved laterally one row, and the process repeated.

In all, the plate now contains approximately 2100 holes of 5/64" diameter on 1/4" centers, in a staggered pattern. The top of the plate (the side the grain will rest on) was first filed smooth with a standard mill file. On the other side of the plate (toward the bottom of the tank) I ran a countersink into each hole using what machinists commonly call a "center drill". This is a special, short drill bit having a small diameter leading section 5/64" in diameter, followed by a tapered section which expands out to the drill's maximum diameter of about 3/16".

In the center of the plate, I drilled the existing 3/16" diameter hole out to 1/2", then continued to expand the hole size by making a precessing orbital motion (and other abusive maneuvers) with the drill. I got the hole large enough to get a 1/2" NPT pipe tap started into the hole and tapped it until the tap passed through the hole.

From the top side of the plate I threaded in a 1/2" to 1/2" copper (F) to NPT (M) copper coupling, threading in up to its hex shoulder. From the bottom of the plate, I threaded a 1/2" to 1/2" NPT (F) to copper (F) coupling onto the threads of the first coupling, again threading this on until the coupling's hex shoulder came up to the bottom of the plate. Finally, I soldered the male end of a 1/2" copper street el into the coupling on the top of the plate, and soldered a 3" piece of copper tubing into the female end of the el. The keg drain pipe that extends into the keg is now shortened and extends only about 2" into the keg. This drain is coupled to the pipe attached to the screen plate with a short piece of the silcone tubing described elsewhere.

Since the screen plate (false bottom) is 14 3/4" in diameter and is a single, unhinged piece, radial slots had to be cut into the top of the keg (the opening on the mash tank is a 10" diameter hole). Also, the clearance between opposite sides of the rolled lip of the top end-ring is only about 13 5/8", so that rolled lip had to be slotted as well. I used a hacksaw to cut 1/4" wide slots starting at the 10" diameter opening and extending outward radially until the saw blade hit the end-ring. I then continued the cut outward about 2/3 of the width of the end-ring's rolled lip. Using a 1/4" drill bit, I blasted a hole vertically downward through the lip nearer the outside diameter of the end-ring, midway between the two parallel saw cuts. This hole provided the ending point of the two saw cuts. This process was repeated on each diametrically-opposed side of the keg, and provided a 15" wide "slot" for the screen plate to slide through on edge. The new plate can now be easily installed and removed with one hand, whereas the previous two-piece model required three hands.

When the alumimun false bottom is installed in the keg, the lower coupling extends to within about 3/8" of the bottom of the keg. The amount of liquid inaccessible for pumping is now about 1 cup (200 mL?) or so, and the amount of liquid below the screen itself is about 3 1/2 quarts, down from the 3 gallons of the previous design. We expect this reduction will make brew volume planning a little easier.

The holes in the new plate provide about 60% greater hole area than the previous pizza pan design, even though the holes are smaller in diameter. The back-relieved design of the holes (each hole has a considerable conical countersink on the bottom of the plate) was intended to provide for the passage of grist debris, and to emulate the V-wire design of commericial lauter tuns.

The Process

The Sparge

[Referring to Prototype I] We didn't know how sparging would go with the unproven screen design--if the holes would be too big, too far apart, or just the opposite. We lucked out and aparging is a brewer's dream with these filters! You can pump from the mash tun nearly as fast as you please, and even let the grain bed go dry--and still the water flows. What's more, after only about two minutes of recirculation, the wort 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. Feeling we might gain better extractions with slower sparges, we plan to determine the exact limits of pump flow through the use of the pump outlet ball valve. With the batches conducted so far, we've only been able to sparge for about 25 minutes before using all available sparge liquor. NOTE: We have been able to slow sparge and mash flows to the point where sparge for a 10-gallon brew length can be held to about 45-60 minutes. Our data shows final runnings clocked in at about 3 deg Plato at the end of the sparge. After the boil was under way during the last brew, we did a final drain of the mash tank, obtaining 1.5 gal of 3P wort, which we used to make up bottles of starter.

Prepping for the Fermenter

When the boil is finished, we pump from the kettle back to 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 hot bitter wort in our sparge tank (the 50L Euro style Becks keg). This tank is shorter than a Sankey and has a 12" hole in it rather than the 10" holes cut into the mashtun and kettle, 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 12 gallons in about 15 minutes.

Max Capacity Batches

To prevent an unprofessional-looking boilover, maximum kettle volume for a boil is about 13 gallons, for a maximum finished product volume (with a 90 minute boil) of about 11.5 gallons. One way to overcome this limitation would be to split the sweet wort evenly between the sparge tank and kettle, then use both containers to conduct the boil. This could be done in the following way:

Use all the water from sparge tank during an initial sparge, pumping the kettle full in the process. Then, pump half the kettle contents into the emptied sparge vessel. At this stage, there would be about 7 gallons in each boiling vessel. Next, begin a second final sparge using about 2 gallons of pre-treated sparge liquor. Using sight glasses installed on both the sparge tank and kettle (or dip sticks), sparge through 1 gallon of water into each of the boiling vessels in turn. This would provide about 8 gallons in each vessel. Finally, boil wort down in ach tank to the final target volume. Using this technique, I believe this system could be used to conveniently produce a 15 gallon finish batch with a single mash. This concept raises a new problem however: what to ferment in.

Notes from the Field

We're continuously improving this system, which is already fun to use. First, the vinyl tubing which is only rated for 140F had to go. It stains, smells, has poor mechanical strength at elevated temperatures, and does not like long exposure to chlorine sanitizer. I now have a braid-reinforced silcone tubing that better meets our needs. A lot of Teflon tubing is less expensive, but is almost rigid and requires swage-on fittings. The silicone tubing is available from a number of sources, including Pure-Fit, Inc., and NewAge Products. Visit your local library and search under Tubing in the Thomas Register. This tubing costs anywhere from $8.50 to as much as $13.50 per foot, depending on the source and quantity purchased. It is recommended for food, pharmaceuticals, blood or other sanitary uses and where high flexibility and high temperatures are encountered. It is steam sterilizable and rated to 500F.

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 as a tangential injector (like the big boys) to spin the wort at kettle-out. Combining this mechanical action with a little Irish Moss might improve beer clarity going into the fermenter. With 20 gal SS stock pots costing as much as $400, we'll have to make do for now. I'm planning to test this idea, however, using real wort with real gunk in it and a modified plastic garbage can. The idea is to determine if the capacity of the pump and the shape of the "kettle" are sufficient to precipitate a significant amount of trub prior to kettle pump-out.

Finally, know what you're trying to accomplish with your system. Our objectives are now more focused on repeatability and on fully understanding why changes made to procedures/equipment/materials have the effects they do. For example, extraction efficiency might be an expected consequence of actions taken to improve the process, but it isn't an important objective to me right now. Continued system development will be driven more by our objectives of improved "observability and controllability". Accurate and properly placed instruments and sight glasses will ensure temperatures and volumes are measurable, while more finely adjustable burners and improved pump flow will lead to better temperature and sparge control.

The Future of this File

Check back at The Brewery from time to time for changes to this file. As system enhancements are made I'll make a special effort to post them and the results of their use to this file. I also hope to add in some linked graphics where they seem most effective in conveying information. If you have questions regarding this system please feel free to contact me at my email address at the top of this document.

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