Final answer:
The run around pump in hot water boilers is used to increase circulation within the system, but not specifically for the purposes of increasing temperature quickly, balancing pressure, or increasing discharge pressure. The correct option that describes its purpose is: (a) to increase circulation and bring the boiler up to temperature faster.
Step-by-step explanation:
A run around pump in hot water boiler systems serves to maintain consistent circulation and temperature throughout the system. Its primary purpose is not to quickly increase the temperature of the boiler, nor to modulate pressures between discharge and return lines, or to increase the discharge pressure directly. Instead, it is part of the hydraulic circuit that ensures continuous and efficient operation by balancing the flow through the pipework and avoiding thermal stratification.
The topic involves principles of thermodynamics and fluid dynamics, such as the ones demonstrated by the entrainment devices seen in FIGURE 12.5. These devices create a low-pressure area by increasing fluid speed, which then entrains one fluid into another resulting in a mixture or movement. While the examples given – such as the Bunsen burner, atomizer, and aspirator – are different in application, they share the underlying physics with the function of a run around pump, which coordinates the movement and mixing of hot water within a boiler system.
Thus, considering the options provided and the context of a run around pump in a hot water boiler system, the correct option that describes its purpose is: (a) to increase circulation and bring the boiler up to temperature faster.