Draft systems are usually designed to a temperature of 38°F. Like any mechanical system, fluid dynamics plays a vital role in the design of the system. On top of this, designers must take into account the carbonation on the fluid flowing though the tubing. In other-words, beer is alive and behaves differently than other fluids. Designers of a draught system should always have the same goal in mind: move the beer from source (the keg) to glass as the brewer intended the product to be presented to the customer. This means that "balance" is the most important aspect on the design of a draft system.
What is balance? In a nutshell, the short answer is: pressure is used to move beer from a keg using a gas (usually CO2 or a blend of CO2 and Nitrogen) to move the beer from the keg and replacing the outgoing fluid with gas while maintaining a flow of about 2 oz per second (or one gallon per minute) at any point in the draught system. Temperature affects the flow-rate of any liquid and beer is no different. This is why a standard of 38°F is established by The Brewer Association (see link below). There is a vast amount of engineering that goes into complex systems (such as those found at The Yard House, for example), but the end-goal is the same. Balance, balance, balance.
So why is this important, you ask? Well, failure to maintain proper balance will cause excessive foaming and ultimately loss of product that should end up in the customer’s glass. In other words, loss of beer! However, when proper balance is maintained, the beer arriving to the customer is around 40°F. This might be acceptable for some styles, but not ideal for the mass-produced Lager. So, most establishments that have a mass-produced lager as their main seller will have the cooler temperature ramped down to 32°F or below! Thus, the balance integrity of the system-design is compromised.
Have any of you ever gone to a sports bar and ordered a beer from their draught system? If you have, nine times out of ten the beer will arrive in a frosted mug and the beer itself will be borderline frozen. No head presence in you beer and an absolute lack of flavor.
Ice-cold beer (or any beverage, for that matter) will numb your tongue, rendering your taste-buds useless. A good example to use are the Hooters restaurants. Most of them proudly display the temperature of the beer cooler at 32°F or below!! Now, this is ideal for dousing the heat from their famous hot wings. However, this doesn't do any favors to the beers they serve. Especially now since most of the Hooters franchises are finally catching on to the thirst most Americans have for the Craft Beer Industry. Unfortunately, all beers are (for the most part) are kept in the same walk-in fridge. End result? Over foaming pour into a frosted mug leading to flat, way-too-cold, flavor-altered craft beer. Why? Draught system is not in balance.
Author's Note: I have nothing against Hooters (in fact, I love their wings!). I am simply using them as recognizable example to prove my point.
Now for most ales, the ideal serving temperature is between 45°F and 55°F. Lager beers are ideally served at slightly cooler temperatures, depending on region and type of lager beer. Personal preference comes into play, naturally. There are various exceptions and deciding factors for serving temperature, but this is a basic catch-all temperature range. Just like with most foods, you want to eat them warm because they do not taste the same when cold. The same is with beer: the warmer it gets, the more flavor that is released. The obvious exceptions are the mass-produced, light tasting lagers. Have you ever had a mass-produced lager after it has warmed up? The vast majority of them taste like crap outside of 38°F (+/-). Now you know why they are advertised to be served as cold as possible. Throw in the numbing of taste-buds and heat dousing purpose of having a cold beverage and you know why "the colder the better" method is used for some establishment.
My recommendations are few and simple:
1) Ask your server for a chilled glass, not a "frosted" glass. A glass kept in a cooler is less likely to have frost deposits than a frozen glass; all that "frost" ends up in your beer, altering the flavor. Plus, this makes it difficult to assess the temperature of the beer in the glass. You want the glass to be as cold as the beer, not frozen.
2) Most of us don't carry a drop-in thermometer (hell, I don't). Knowing a draught system is typically at 38°F (sometimes even colder and it might be displayed), the temperature will be too cold for the beer style you ordered. Let it sit for a few minutes before you begin enjoying your brew.
Of course, these are mere recommendations and every person has his or her own preferences. Hell, I have been known to have an American Adjunct Lager while having some hot-wings. Why not? It’s a great combo when I’m focused on watching a game and having some bar-food. However, in other appropriate settings, temperature is important. Maintenance and stability of a draught system will ensure quality in your glass before it even reaches your lips. The bottom-line and profit margin of some establishments may cause for alternate decisions to be made, affecting the draught system. If so, just remember 45°F to 55°F is ideal and will capture most styles nicely, and slightly colder for most lagers. Let the beer sit for a bit, and then enjoy!
-Gilbert “Charlie” Perez, Certified Cicerone®