Is your kegerator dispensing foamy beer? It is often the case that when a new keg is hooked-up, the first few pints are mostly foam. If the foam persists, you may have a deeper problem. Most cases of foamy beer have to do with temperature, but sometimes hardware failure or even unclean beer lines can contribute to this problem. But - there is no problem that cannot be fixed!
Step 1: Temperature should be mid-low 40's F (liquid temp, not air temp)
Step 2: Clean the beer line or replace
Step 3: Beer line should be 3/16" diameter
Step 4: Use beer line that is 8 feet long
Step 5: Set regulator in the 5-10 PSI range. Adjust as necessary.
Step 6: 24 hour keg rest after transporting for CO2 to reabsorb into the beer.
Step 7: Watch for beer line dipping below the level of the top of the keg. Coil beer lines on top of the keg.
If you are having consistent foam over problems, you should first understand that it takes time for a keg of beer to settle after transportation. The shaking up a full keg of beer happens to a great degree just from traveling a few blocks by car. Plus, if the keg temperature has changed during transportation, you may have a temperature-related problem as well. Once a keg is installed into your kegerator, you should give it at least two and preferably four hours to 'settle in' before pouring. Also, make sure you are pouring with the glass at an angle, and this will help reduce foam from an improper pour. A proper pint glass is helpful as well.
Beer Foam Physics
One should understand the physics behind foamy beer! Most beer is carbonated, meaning that it is a liquid solution saturated with a large amount of CO2 gas. When a liquid is saturated with CO2 gas, more gas stays in the mixture at colder temperatures. In this case, the beer gas/liquid solution holds itself together the best right around 34-38 degrees. When the temperature rises above 40 degrees, the CO2 gas starts to escape from the beer, and this is what causes foam (in most cases). For this reason, temperature issues constitute the great majority of problems with kegerators serving foamy beer.
Now that we've gone over the basics, check your CO2 regulator settings. Beer can be pushed at anywhere from 4 PSI to 14 PSI, but most kegerators work best between 5 and 12 PSI. You should compensate for the size of your beer lines - the bigger the inner diameter of the beer line, the more pressure that should be used to push the beer. The colder the beer, the more pressure you can use as well. High pressure and high temperature will cause excess foam to result. If your beer lines are on the small side, like ¼" inner diameter, this can contribute to foaminess.
For more persistent foam problems, you should verify that your kegerator is cooling beer to the proper temperature. You can double-check the cooling at both the top and the bottom of your kegerator by placing a glass of water near each location overnight, and measuring the resultant temperature in the morning with a standard thermometer. If you have a draft tower, you should ensure that cool air is circulating through the draft tower as well as the refrigeration compartment. If the beer is cold at the beginning but raises temperature at the end of the beer line, it can cause a great degree of foaming.
If this is all in order, it is time to check the condition of your beer line and fittings. Dirty beer lines can cause foaming as well, and this makes it very important to clean your beer lines regularly. Now, check all fittings. If any of the fittings are loose, it can cause outside air to be sucked into the beer solution, causing air bubbles and foaminess. Make sure to tighten all of your hose clamps and any fitting that has bolts or hex flanges.
In some cases, your beer line may not be long enough - about six to eight feet of beer line is optimal.
If all else fails, you may have to look to your CO2 regulator. If the regulator has been dropped or banged up (they usually are), you might have a regulator malfunction that is causing a gauge to fail or let excess CO2 into the keg.