What type of plug is used on two-pipe oil systems and is placed in the oil pump?

The use of a bypass plug in two-pipe oil systems, especially in the oil pump, is crucial for ensuring proper operation and efficiency of the system. The bypass plug allows excess oil to flow back to the oil tank instead of causing pressure build-up within the system. This operation is essential to maintain optimal performance, as it helps regulate the pressure in the oil lines and prevents potential damage to the pump and associated components.

In two-pipe systems, maintaining the right balance of oil flow is critical, and the bypass mechanism is designed to facilitate this balance by returning oil to the tank once it has circulated through the system. This action not only protects the equipment but also ensures that the system remains efficient and avoids issues that could arise from excess pressure.

In contrast, the other options serve different functions or may not be applicable in the context of an oil pump setup within a two-pipe system. Knowing the specific roles and mechanics of these plugs is essential for maintaining the reliability and safety of heating oil systems.