Closed-System Home Brewing


by Bennett Dawson (Brewing Techniques) 



A problem with airborne contaminants led to the development of this completely closed system, in which wort and beer never contact nonsanitized environments, even ambient air.



When I opened my homebrew store in northern Vermont last year, I immediately had problems with a mysterious contamination in all of my brews. I have a kitchen set up in the store, and everything I brewed showed signs of bacterial or mold contamination in the secondary fermentor, even though I preboiled all brewing water and did a full wort boil. I couldn’t figure out where my sanitation was breaking down, so I called Greg Noonan, owner of The Vermont Pub and Brewery, which is located about 25 miles from my store. Greg suggested that because the infection seemed to take hold when I racked to the secondary it was probably resulting from airborne mold or bacteria.

The problem turned out to be a plugged drain pan in my air conditioner. This miniswamp was growing the most virulent cultures of spooge you’d ever want to see. Every time I turned on the air conditioner I pumped the store full of black mold and other really bad stuff at high enough concentrations to contaminate the wort even with limited exposure.

During the process of sanitizing my air conditioner, I developed the procedures described below. Even without an air conditioner contributing to the problem, home brewers in the Champlain Valley of Vermont face high concentrations of airborne molds during the summer. When Greg visited my store last year we discussed all of this, and he enthusiastically endorsed the brewing techniques outlined here. “It’s how we do it at The Vermont Pub and Brewery,” he said.

If you are thinking about purchasing a kegging system, you should know all the benefits available from a system that uses a carbon dioxide tank. (You can also rent tanks and regulators.) Not only can you purge receiving vessels with carbon dioxide, but you can also enjoy the fun and ease of pushing your beer with carbon dioxide pressure.

Operating a closed system is a more relaxed way to brew. The only time you will need to suck on a hose is when you start the wort chiller. If you keg your beer, it will go from the brew pot to the keg tap without exposure to the unfiltered atmosphere. You can relax and quit worrying!

Warning: When using carbon dioxide to push beer from carboy to carboy to keg, do not use clamps to secure the carboy caps. This can lead to a shattered carboy and glass shards and beer everywhere! I have learned to rely on the carboy cap’s ability to blow off if the internal pressure exceeds its gripping strength. The caps grip well enough to do the job without clamping.


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Purging Carboys


You will need a carbon dioxide tank and regulator, two carboy caps, two straight racking canes, ⅜-in. i.d. hose, and a glass carboy. First sanitize the carboy and all equipment. Adjust the pressure on the regulator to 0 psi before getting started. Attach the hoses as shown in Figure 1. Let the carbon dioxide flow (under low pressure) into the carboy. A slow flow for 1–2 min is sufficient.


The Wort Chiller


An immersion chiller is easy to make and use, but a counterflow chiller gives you that extra bit of protection, plus allowing you to make a hop back. A kitchen-sink-ice-bath counterflow chiller works very well. Use 50 ft of ⅜-in. copper tubing and bend carefully. A spring-type tube bender costs less than $ 5.

Step 1: Carefully lift your brew kettle onto a bucket set up on your counter. Whirlpool the wort, cover, and wait 15 min. Use this time to set up the ice bath and to purge the carboy with carbon dioxide.

Step 2: Gently place the racking cane into the brew pot as shown in Figure 2. The hops residue will have settled into the center of the pot; if you rack slowly, you will be able to leave most of it in the pot. To start the siphon from the brew pot, dip a gloved hand (inexpensive surgical gloves cost $ 8 for 50 pair) into iodaphor, wrap it around the hose (see detachment point, Figure 2), and suck on your hand, not the hose. If the flow from the copper racking cane is not filling the ⅜-in. hose, gently pinch the hose where it meets the cane; this eliminates the air pocket, allowing wort to flow smoothly. Control the final temperature of the wort by adjusting the flow through the wort chiller. A stick-on liquid crystal display thermometer placed low on the carboy works great to monitor the wort temperature to determine the correct flow rate.


The Wort Chiller in the Hop Back


I have seen diagrams for an in-line hop back made with mason jars and screens, but a bucket fitted with a false bottom (both sanitized) works fine (Figure 2). If you don’t have a false bottom, you can put your hops in a muslin sack next to the outlet hose.

Don’t use a plastic spigot for the hop back because the high temperature will cause it to leak. Instead, drill a ⅜-in. hole at the bottom edge of a bucket and push a section of ⅜-in. i.d. hose through. (It helps to soften the hose in hot water first.) Rack the beer with a ⅜-in. copper cane from the brew pot, down onto the hops, and out the runoff hose and into the ice bath wort chiller. Raise the hop back a few inches above the counter to increase the gravity-feed pressure. Use a clamp to control the flow so that the hops become saturated in 1–2 in. of wort (especially if you use a muslin sack), then let it flow through the wort chiller. Use a clamp at the outlet of the chiller to regulate the flow, and thus the temperature, of the wort.

The bed of hops will filter out some of the trub and almost all of the boiling-hops residue. Tip the kettle gently as you get to the bottom of the pot.

Be very careful when starting the siphon for the hop back wort chiller — a mouthful of hot wort is no fun at all. A stainless steel spigot in the side of the brew pot makes moving the hot wort from the kettle to the hop back much safer.

If you feel uneasy about putting a kettle full of 212 °F wort up on a high platform, an acceptable alternative is to ladle the wort into the hop back with a saucepan. Try not to splash because hot wort aeration leads to other problems. Siphon or ladle 1 gal of hot wort into your hop back before letting it flow, and maintain this level for smooth, continuous flow. Feel free to add more hops to the hop back during this process.

(Clean the counterflow wort chiller by pouring boiling water into the hop back, followed by a brief iodaphor flush and then more boiling water. Blow all remaining liquid out with carbon dioxide before capping the ends with #000 solid rubber stoppers.)

By following these procedures, you will have clean, cool wort in a closed and sanitary carboy. You can let the trub settle for a few hours, or even overnight if you want, before racking off the trub, aerating the wort, and pitching the yeast. Leave the carboy cap and hoses in position for racking. Let the hoses hang into your iodaphor bucket while the trub settles.

If you plan to wait for the trub to settle out before racking to another carboy for pitching yeast, make sure the wort is below ambient (room) temperature. If the temperature drops with the setup in place, the contracting (cooling) wort will suck iodaphor up the hoses and into the carboy.


Racking off of Trub, Aerating Wort, and Pitching Yeast


Step 1: Set up the receiving carboy as shown in Figure 3 a. For the receiving carboy, use a 6–12 in. section of ⅜-in. rigid tubing (bottle filler tubing) inserted into the angled side of the carboy cap (I had to cut my cap to make it fit), and purge the sanitized receiving carboy with carbon dioxide.

Step 2: Attach ⅜-in. hoses as shown in Figure 3a. Slowly screw in the pressure adjustment on the regulator until the beer begins to flow. Don’t rush it! Remember to set the regulator to 0 lb before applying any pressure. It takes only about 2 psi to blow off a carboy cap, which is undesirable because the racking cane will stir up the beer.

Step 3: Push the clear wort into what will be your primary fermentor.

Step 4: If you have an aeration setup (an in-line HEPTA or 0.2–0.5 µm air filter hooked to an aquarium pump), attach the hoses, aeration stone, and carboy cap as shown in Figure 3b, and aerate the wort. Carefully remove the carboy cap enough to pour the yeast culture into the wort, then aerate some more. If you are repitching yeast slurry from a previous batch, you can push some wort from your carboy into your yeast flask and let the yeast come to high kraeüsen before pitching.




Step 1: Attach a sanitized carboy cap and racking cane to a sanitized carboy. Purge the carboy (secondary fermentor) with carbon dioxide. Reset pressure regulator to 0.

Step 2: Flame the top of the primary with isopropyl alcohol. (Even though the carboy was sanitary when fermentation started, plenty of airborne bacteria may have landed on the rim by the time you rack your beer.) Next, remove the stopper and insert the carboy cap and racking cane.

Step 3: Attach ⅜-in. hoses as shown in Figure 4. Gently place a short length of a 2 X 4 board under one side of the carboy. Move the carboys apart to get the racking cane to stay pinned to one side.

Step 4: Slowly screw in the pressure adjustment on the regulator until the beer begins to flow. Remember, the pressure of the carbon dioxide of the glass carboy can be extremely hazardous, especially is the cap makes an inadvertent seal. Use every precaution.




Step 1: Sanitize and purge a keg with carbon dioxide.

Step 2: Use a keg fitting with just enough “beer line” on it to cover the shank. This mates nicely with the ⅜-in. i.d. hose. Attach the keg’s carbon dioxide line and let it hang down into the iodaphor bucket to allow pressure to escape from the keg while it fills. Push the beer from the carboy into the “liquid” side of the keg.

Step 3: Detach the hoses and carbonate the beer. If you keg-condition your beer, add the priming sugar before purging the keg.

Even if you use only one or two of these racking and kegging techniques you will greatly reduce the possibility of airborne contamination.




Step 1: Pour the priming solution into a sanitized carboy. Attach a sanitized carboy cap and racking cane and purge the carboy with carbon dioxide, as described previously.

Step 2: Push the beer into the bottling carboy and then, without removing the cap, give the mixture a few stirs with the cane.

Step 3: Swap hoses and attach bottle filler as shown in Figure 6. A pressure of 0.5–1 psi is enough to push the primed beer up the hose and into your bottles. It will be a lot easier on your back and knees if you have the carboy and carbon dioxide tank on the floor while bottling up on the counter.


Harvesting Yeast


Whether you bottled or kegged your beer, you now have a secondary fermentor filled with carbon dioxide and yeast. If you racked the beer from the primary to the secondary soon after the kraeüsen fell, the yeast on the bottom of the secondary should be healthy, not too dusty, and ready to be repitched. If you plan to cold-condition the beer before kegging, rack the beer again and harvest the yeast before putting the beer to cellar.

Step 1: Leave the carboy cap and cane setup in place while you swirl the beer–yeast mixture to get the tightly packed “toothpastey” stuff off the bottom (Figure 7).

Step 2: Push the slurry up the cane and safely into a carbon dioxide-purged flask or bottle for later use.

Step 3: Pour 12 oz of sterile wort into the flask to give the yeast something to eat (slowly) while it sits in the refrigerator; let it start fermenting just before putting it into the refrigerator. If you take it out 2–4 h before brewing, it will be almost crawling out of the flask by the time you are ready to pitch.


Worry-Free Brewing


By preventing the wort and beer from contacting even the ambient air of the outside environment, closed-system brewing offers the ultimate in worry-free brewing. The beers produced in such a sanitary environment are high quality, and the methods required are in many cases easier than in other systems.


The author thanks Dan Gates for providing the basis of the yeast harvesting method.

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