Final answer:
The condenser water return line is typically cold to touch because it transports water that has collected heat from the air-conditioned space to the condenser. The line may also be identified by labels, insulation, and system diagrams such as a "Condenser diagram."
Step-by-step explanation:
To identify the condenser water return line in a cooling system, the common characteristic is that it is cold to touch. This is because this line carries the water that has absorbed heat from the air-conditioned space and is on its way back to the condenser to be cooled again. However, it's essential to note that the actual return line may have several identifying features, such as being labeled, insulated, or recognized through a system diagram. A condenser diagram may provide clear identification to avoid any confusion.
One should look for labels or other forms of identification as the primary way of distinguishing different lines in a system, always considering safety and system-specific training. Additionally, using a diagram like the "Condenser diagram", as referenced, can be a helpful tool in identifying the condenser water return line.