A glycol system is a system of maintaining the temperature of draft beer; the beer itself is stored in a separate room or area than the tap itself, and the glycol system keeps it cold in the kegs and while it travels through the lines to the tap. If you have a glycol system or are installing one in your bar or restaurant, note a few things to keep in mind about the system so you can ensure you keep it maintained and in good working order at all times.
1. The glycol bath itself
The glycol bath is a liquid mixture that is kept at a constant chilled temperature and which is then circulated around the kegs where the beer is kept, and sent through a separate tube or hose to the taps as well. This keeps the beer cold in the kegs and keeps it from getting warm as it travels to the tap. The glycol travels a circuit, with the warm glycol going back to the bath to be chilled and circulated again.
2. The compressor and pump
The glycol bath is kept in a separate container and a part called a compressor chills a coil underneath the bath. This coil then keeps the glycol at a constant temperature. A motor pumps the glycol through the lines when you open a tap.
This is important to know because if your beer is coming out of the taps warm, you can check the kegs first. If the kegs are warm, this means there is something wrong with the compressor that chills the glycol or with the coil that is meant to keep it cool. If the kegs are cool, the compressor and coil are probably working but there is typically something wrong with the motor or pump; when these fail, they don't pump chilled glycol along with the beer and it gets warm before it reaches the tap.
3. Maintaining the system
Don't wait until your beer gets warm before you maintain the system. Check for ice twice per year or as often as recommended by your manufacturer; if there is ice in the glycol, it's being kept too cold and this ice can clog the lines. The bath also breaks down and turns into water over time, and if this happens, the water can freeze and clog and damage your lines. Note how often you need the glycol bath replaced according to your manufacturer, and be sure you have this done.