If there is an air lock after repairs have been made on the piping system, the operator should:

When dealing with an air lock in a piping system, the primary focus is to release any trapped air, as air pockets can disrupt the proper circulation of water, leading to inefficient operation and potential damage. Opening the system's vent valves or checking the operation of the automatic air venting system is the most effective method to allow air to escape.

By opening the vent valves, the operator creates an outlet for the trapped air, thus restoring the flow of water in the system. Automatic air vents are designed specifically to eliminate air from the system as needed, and checking their operation ensures they are functioning correctly, which is essential for maintaining system integrity and efficiency.

Increasing water pressure, turning off the heat source, or draining the system would not specifically address the issue of trapped air and could potentially complicate the situation further. Thus, the chosen action of venting the system or ensuring the air vents are working is the proper solution to resolve an air lock effectively.