How Kegerators Work

Stacks of kegs
Kegerator systems store a keg inside a refrigerator to keep it cold, while still allowing access to the beer through a faucet in the door.
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At some point in their lives, many adults have picked up a red plastic cup, waited in a line in a backyard and attempted to fill the cup with beer from a keg. They know what it's like to find themselves tipping the cup at an angle, kneeling down below the keg's lid, or finding a friend to pump the tap while they poured. Regardless of the amount of preparation on the party planner's part, kegs in general tend to be a difficult beast to control. They can be unreliable, tricky to keep at a good temperature and difficult to maintain over the course of evening.

This is where kegerators enter the scene -- kept at a perfect temperature, they are able to dispense beer quickly with little trouble. By taking apart the word "kegerator," you'll find its definition: a refrigerator with a tap protruding out that is connected to a keg inside. Kegerators come in a variety of shapes and sizes. They can be purchased, rented or built, and they're a good system for keeping beer fresh for long durations of time, which minimizes waste.


Although an accurate history of the kegerator is difficult to trace, it is likely kegerators were in existence as early as the 1900s. However, the Prohibition period and World Wars I and II -- not to mention costs in the years that followed -- kept home brewing at bay until about the 1980s. Home brewing then began to grow in popularity, and so did the kegerator.

As we'll see throughout this article, the kegerator is an indispensible tool for the home brewer and beer connoisseur alike. But up first, we'll take a look at the main parts of a kegerator and how they work together to keep beer fresh.


From Keg to Tap

Kegerators are a remarkably simple system, and regardless of shape or size, they should all have the same basic components:

  • Carbon dioxide (CO2) cylinder
  • Carbon dioxide regulator
  • Coupler
  • Tubing (special carbon dioxide tubing as well as line for the beer)
  • Keg
  • Faucet
  • Refrigerator

A kegerator works by applying carbon dioxide pressure on the keg in order to push the beer upward and out of it. Although carbon dioxide is a natural by-product of fermentation, the cylinder allows for constant and even pressure to be applied to the keg while it's tapped. This helps maintain consistency and carbonation. The cylinder filled with carbon dioxide is connected to a regulator, an instrument that allows you to change the pressure. The coupler, or the valve that taps the keg and allows beer to flow from it, uses a separate tubing input and output. One tube leads from the regulator to the "in" part of the coupler, and another tube runs from the "out" part of the coupler and ends at the faucet, out of which the beer is poured into your cup. The keg is usually stored inside a refrigerator, which has the faucet on the outside.


One of the main benefits of the kegerator is its ability to keep beer fresh for long periods of time. Beer stored in a kegerator should stay fresh for at least one month, but it can stay good for up to four months if the keg is kept pressurized and properly cooled [sources: BYO, Kegerators]. Several components factor into beer spoilage, but you'll learn more about that later in this article.

The most important facet in dispensing a perfect glass of fresh beer is the temperature. This is where a standard keg in someone's backyard falls short. But because the keg in a kegerator is kept refrigerated, this is easy to regulate. Most beer that is stored cold is kept at about 36 to 40 degrees Fahrenheit (2.2 to 4.4 Celsius), although this changes from beer to beer. Storing it at a temperature that is too high or too low can affect the beer's flavor [source: Anheuser-Busch]. Measuring the temperature can be done in number of ways: Some prebuilt kegerators may come with a temperature gauge, but for the thrifty, a glass of water with a thermometer kept in the kegerator can give an accurate reading.

If a kegerator sounds like the kind of thing you'd like to have in your home, read on to discover what options are available.


Different Types of Kegerators

White retro refrigerator
If you don't want to go out and purchase a kegerator, you could buy a used refrigerator and convert it.
Hulton Collection/Getty Images

There are a few ways to get a kegerator for home use, depending how you plan to use it and how much you want to spend. If you need beer for a one-time event, you'll likely be able to rent one. If you're more interested in the year-round consumption of a fresh brew, you have two options: to buy one or build it yourself. Much like refrigerators, kegerators come in a variety of shapes and sizes. They can hold varying keg sizes, be modified for home brew or retail beer, and come with side- or top-mounted faucets.

If you are handy with tools, then building your own kegerator may be a good solution for you. Many retailers supplying premade kits for modifying an existing refrigerator, so building your own is more cost efficient if you already have an old refrigerator that isn't getting any use. If not, you may be able to purchase a used one that you can modify. The most important part of building your own is ensuring that the refrigerator has enough space to hold the size of keg you want in addition to the carbon dioxide canister and tubing.


When deciding whether to build your own, you'll also want to factor in the type of beer you'll be serving. Home brews are often stored in 5-gallon (19-liter) soda kegs (also called Cornelius kegs), whereas those from liquor stores tend to be larger [source: BYO, Kegworks]. The coupler that attaches to these kegs is different as well, with six variants in all. Your local liquor store should be able to supply you with the proper coupler once you tell them what type of beer you'll be dispensing. Most North American lagers use a "D" system, which is by far the most common of the six types. If home brewed beer is more your thing, then you'll probably be using the soda kegs, which generally require a special ball and pin type coupler [source: Micromatic].

With all these components involved in the beer storing and serving process, you may be wondering whether it comes along with any risks. In the next section, we'll look at how to properly maintain a kegerator as well as highlight some safety concerns that come along with using the system in a home.


Maintenance and Safety

Kegerator systems aren't dangerous in general, but because they use pressurized gas, they do have to be handled with care. As a general rule of thumb, all carbon dioxide canisters must be kept in the upright position once filled. Carbon dioxide is not shipped, so canisters must be filled locally. This can be done at many places, including paintball shops or welding stores.

Replacing the keg also consists of several important safety measures. First and foremost, the intake valve of the carbon dioxide canister must be closed before it can be disconnected. Once all pressure has been released, the keg can be taken out and replaced. Although major injury is unlikely, a room filled with a few pounds of carbon dioxide can make you sick and lightheaded. It's also important to remember that kegs can weigh up to 160 pounds (72 kilograms) when full, so you might want to have a friend around when you're replacing an empty one [source: Micromatic].


In order to have a truly great glass of beer every time, the kegerator requires regular maintenance. This means you need to clean the line leading from the keg to the faucet in addition to the faucet itself whenever you change out the keg. This is typically done with a special line cleaner to ensure the tubing is completely cleaned of all elements. Be sure not to use water that is very hot, because it could alter the shape of the beer lines and lead to faulty pouring. Once you're through cleaning and have fully rinsed the system with cold, clean water, it's also important to run a few glasses of beer through the system before drinking, just to ensure all lines have been flushed of the cleaning solution.

Proper maintenance leads not only to a better tasting beer, but to a longer lasting one, too. Cleaning the system helps keep out harmful bacteria, which would spoil the beer. Maintaining pressure and keeping the carbon dioxide system closed prohibits oxygen from entering, which could also ruin the beer.

Having your own kegerator doesn't require just work and upkeep, though -- it also comes with a price. Read on to find out how much a kegerator will cost and whether it might be worth it.


Cost and Benefits

If you're planning to serve a large amount of beer, then investing in a kegerator may be more cost efficient than constantly purchasing bottles or cans. A kegerator itself can range in cost anywhere from $200 to more than $2,000. The carbon dioxide canister may cost about $20, with refills costing about $7 to $12. Full-sized kegs start around $70, but they are recyclable and refillable, which helps eliminate the waste of individual cans or bottles.

A full-size keg of a cheaper American brew retails for around $68.99. In order to purchase a close equivalent, you would have to buy about nine 18-packs at $12.99 each, bringing your total to about $117 before tax. Similar results are found with various other beers, from local micro-brews to nationally recommended brands.


Although the keg in the kegerator requires constant refrigeration, it shouldn't cost any more to run than a normal refrigerator would. In fact, it may have less power consumption, since the door is opened only when the keg is replaced or the lines are cleaned, as opposed to every time you would like another beer. Of course, having two refrigerators running is bound to influence your electric bill, but the kegerator as a system is rather efficient with its power consumption.

Ultimately, though, the choice about whether purchasing a kegerator system comes down to how often you serve beer and how much of it is consumed.

We've already talked about cleaning and maintaining your kegerator with the right pressure and temperature, but you still might come across a few issues when learning to operate the system. Read on to find ways to troubleshoot problems with your kegerator.


Problems and Solutions

Owning your own beer dispensing system in your home probably won't come without its complications. Many problems can be fixed by simple upkeep and maintenance, but sometimes trickier issues crop up and affect the taste of your beer.

For example, as we discussed earlier, the temperature of the keg is very important in pouring a perfect glass of beer. If your beer is producing a sub-par taste or appears too foamy or cloudy, then temperature may be too high or too low. You can usually fix this by changing the refrigerator's temperature to better accommodate the type of beer you're serving or by simply letting the keg cool down more. Many American lagers may be stored and served at about 38 degrees Fahrenheit (3.3 Celsius) temperature, but imports, stouts, ales and others will vary. It's important to check with the liquor distributor before setting up each keg to make sure you are preparing it properly.


Faulty pouring can also be caused by the following:

  • A kink in the lines
  • Incorrect length of hose for the beer line
  • A loose connection somewhere in the system

You can check the connection by making certain that the coupling is tight and that air is not leaking in anywhere. If the beer line is what's causing the trouble, you might need to replace the line to ensure it is correct length.

An incorrect amount of pressure from the carbon dioxide can cause problems as well, but you can check this by keeping an eye on the psi (pounds per square inch, which is the degree of measurement). If the psi is too low, the beer will be flat and pour too slowly, but if it's too high, the beer will pour too fast and have excessive head, or foam at the top. These problems are likely to result if the carbon dioxide regulator is improperly set. The pressure you need will dependent on the type of beer you use, but many beers require about 12 psi to maintain a strong and consistent draft.

For more information on kegerators, pouring and brewing beer and other related topics, follow the links on the next page.


Lots More Information

Related HowStuffWorks Articles
More Great Links

  • Anheuser-Busch. "Beertender Guide." 2006. (November 13, 2009)
  • Anheuser-Busch. "Changing Nitrogen/CO2 Cylinders." October 25, 2007. (November 17, 2009)
  • Brew Your Own. "How long will my beer stay fresh in a keg?" May 2001. (November 19, 2009)
  • Kegworks. "Draft Beer Systems." (November 17, 2009).
  • "History of the Kegerator." April 10, 2008. (November 19, 2009)
  • Micromatic. "Kegerator Door Kit Manual" (November 17, 2009).
  • Micromatic. "Keg Tap Couplers Listing." (November 17, 2009)
  • Skypeck, Charles. "Your Own Draft System." Brew Your Own. June 1995. (November 17, 2009)