A hydronic heating system in a residential building uses a cast iron boiler and fin-tube baseboard emitters. The system is designed as a primary/secondary loop. What is the primary benefit of using a primary/secondary piping arrangement in this scenario?

Question: A hydronic heating system in a residential building uses a cast iron boiler and fin-tube baseboard emitters. The system is designed as a primary/secondary loop. What is the primary benefit of using a primary/secondary piping arrangement in this scenario?

Answer options:

• To allow higher water temperatures in the secondary loop.
• To reduce the system's overall water volume. ✅ To protect the cast iron boiler from low return water temperatures.
• To increase the flow rate through the emitters.

Correct answer: To protect the cast iron boiler from low return water temperatures.

Explanation: Primary/secondary piping is crucial for protecting cast iron boilers from thermal shock and condensation caused by low return water temperatures, ensuring their longevity. It does not primarily allow higher temperatures in the secondary loop or reduce water volume. While it can influence flow, its main benefit here is boiler protection.