A Three-Tiered Gravity-Flow Brewing System
By Bob Caplan
Republished from BrewingTechniques' March/April 1994.
A simple home-built system makes all-grain homebrew a snap.
Many home brewers make fine beers using malt extracts. Adding specialty grains allows brewers to achieve a more personal brew that has more character than extracts alone can provide. The next step, of course, is all-grain brewing. All-grain brewing gives the brewer complete control over the entire profile of the beer. Although mashing grain is quite simple - just heat some water to specific temperatures and steep the grain for a period of time - the process for the home brewer cooking on the kitchen stove can be a nightmare. You need a few big kettles for cooking the grain and then boiling the wort. Often brewers use one kettle for both steps, but the grains must be removed and then sparged to make enough wort for a batch of beer. This can get messy and, depending on the method used, may limit production to only 5 gal of beer.
So what if you'd like to brew 10 gal or even 15 gal with nearly the same simplicity as partial-grain brewing. Can it be done? You bet it can when you brew with the three-tiered gravity-flow brewing system.
The system is basically three kettles (made of Sankey-type kegs) that sit on stands built on three levels so that liquid can flow from one kettle to the next. Each stand has a burner built into it for heating the kettles. The beauty of the system is that you can brew 10-gal and even 15-gal batches in the same amount of time that it takes to brew 5 gal.
This brewing system is available at homebrew supply stores or can be made fairly easily. The system that I use was put together over a few weeks for about $300. My system uses natural gas, but it could be built to use propane or even electricity.
FABRICATIONFigure 1 shows what the system looks like and how it's put together. Each keg has had the top cut off and a side drilled to take a 1-in. brass pipe. (Two of the kettles were silver-soldered; the third was threaded. Both methods work well, but the threaded one looks neater, and stainless steel is difficult to weld.) We used 1-in. nipples and shutoff valves. We added a pipe-to-tube fitting using 2 in. of 1/2-in. copper tubing that would accept plastic hose. This arrangement allows flexibility for racking down from one tun to the next.
The mash tun (vessel 2) has fittings inside and out. We made a ring out of 1/2-in copper tube - its diameter just smaller than that of the inner diameter of the keg - and attached it to the inside fitting. We cut many grooves in the bottom side of this ring to allow liquid to flow from the vessel, through the grooves, and out to the next vessel (vessel 3), leaving most of the grain in the mash tun.
The stands are made out of angle iron. Stands 1, 2, and 3 are 57 in., 36 in., and 18 in. tall, respectively. Each stand is 17 in. deep and 23 in. wide. We changed the original design from 23 in. square to shrink the system's overall footprint. The main structure is 2-in. angle iron with 1-in. angle iron holding it all together. Each stand is welded - we used no bolts - and each is separate from the other, though we tied them together with plastic cable ties for easier portability.
We used gas burners removed from old water heaters. They are plumbed with flex pipe (the same as you might use for a gas dryer) that runs from the burner to the main plumbing structure, which is made out of 3/4-in. black pipe. Each burner has a shutoff valve. I set my brewery up right next to my water heater, and it was very easy to plumb the gas.
OPERATIONThis article discusses what my brewing associates, Rick Caulk and Red Keville, and I have found to be the simplest procedure for brewing 10 or 15 gal of beer in about 61/2 h. The time it takes to brew depends on the presence or absence of a protein rest and the length of the mash rest. The easiest way to explain our method is to describe the brewing process for a recipe for 15 gal of Munchener Helles Bier (see recipe in box).
First, after making sure that all of the kettles are clean, we position them on their burners so that their spigots are aligned to allow the contents of one vessel to flow into the next vessel below it. The lowest kettle (vessel 3) is the one that we boil the wort in, so its spigot needs to be arranged for easy outflow to the fermentation vessel.
To begin, we add 9 gal of water to vessel 2, the mash/lauter tun. (To estimate the amount of water required, we use the rule of thumb of 1-11/2 qt water/lb of grain. For this beer, we use 11/4 qt of water/lb of grain, or 9-10 gal of water.) Next, we light the burner under that vessel. Because we use an upward infusion mash (with a protein rest), we heat the water to 10 °F beyond the target protein-rest temperature; in this case, we rest at 129 °F, so we bring the water to 139 °F.
Next, we pour the grain into the water and lightly stir with a wooden paddle. We turn the fire off and let the grain steep for the allotted rest time, usually 30 min. Although the kettle does not need to be covered, it doesn't hurt to do so, and we use plastic wrap. After 30 min, we heat the water to mash temperature, in this case 155 °F, taking care to stir the grain off of the bottom of the kettle to prevent burning. Because hot spots can occur during heating, it's a good idea to measure the temperature at the edges from time to time and to stir toward the middle to keep the heat constant throughout the mash. When the temperature reaches 155 °F, we turn the burner off and cover the mash with plastic wrap and wait 60 min.
The beginning of the mash is the time to heat sparge water in vessel 1 (liquor tun). It takes our system about 45 min to heat 12 gal of water to ~165 °F, and we time our process accordingly.
When the mash is complete and the sparge water is at the correct temperature, we attach a plastic hose to the mash tun's spigot. If we were making 10 gal or less, we would simply let the wort flow into the boiling tun, but 15-gal batches require us to do things a bit differently.
First, we open the valve and let the wort flow into two 1-gal jugs, which we set off to one side. Then we let the rest of the wort flow into the boiling tun. The middle kettle has the filter to hold back the grain, so the wort runs quite clear. When the wort stops flowing, we begin sparging from vessel 1. I connect a plastic hose to a copper tube with holes drilled in it to disperse the heated water over the grain. Once we have the required amount of water in vessel 3 - in this case, ~12 gal - we turn off the valve and light the burner under vessel 3 and heat to boiling.
About 3 gal of heated water remain in vessel 1, and we run this water into vessel 2. Next, we empty the wort from the two 1-gal jugs into vessel 1 and rack the rest of the wort from vessel 2 to vessel 1 (using the jugs). When vessel 1 contains the 8 gal required to make 15 gal of finished beer, we turn its burner on.
All hops and finings are added to vessel 3 during its boil. Irish moss can be added to vessel 1 when it boils. We allow vessel 1 to boil for about 15 min to sanitize it, and then we chill it. We use an immersion chiller with this system to simplify cooling to pitching temperature. We drop our chiller into the boiling wort to sanitize it, and when it's time to chill we turn the burner off and let the cold water flow through it. After vessel 1 has cooled to pitching temperature (80 °F), we rack it down in equal amounts to our three fermentation vessels and cover it.
When the hop boil in vessel 3 is complete, we transfer the cooling coil to vessel 3 and cool this wort to pitching temperature. To transfer to the fermenting containers, we attach a plastic hose to the spigot and open the valve and divide the wort equally again. Because anything that touches the cooled wort must be sanitized, we store that hose in a sanitizing solution first.
After pitching the yeast, all that's left to do is clean up the kettles and hoses.
That's how simple it is to make 15 gal of beer using the three-tier system. I'm sure other approaches are possible, but this seems to be the simplest way for my brewing group, and it really works.
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