How do copper-tube boilers typically compare to cast-iron boilers in terms of heat-transfer characteristics?

Copper-tube boilers are known for having better heat-transfer characteristics compared to cast-iron boilers. This is primarily due to the thermal conductivity of copper, which is higher than that of cast iron. As a result, copper-tube boilers can transfer heat more efficiently, allowing them to heat water and produce steam more quickly and effectively.

However, while they excel in heat transfer, copper-tube boilers generally have a shorter lifespan than cast-iron boilers. This is because copper can be more susceptible to corrosion and other types of wear over time, especially in environments with aggressive water conditions. In contrast, cast-iron boilers are celebrated for their durability and longevity, often lasting several decades with proper maintenance.

Thus, the correct conclusion is that copper-tube boilers possess superior heat-transfer capabilities but typically do not match the long-term durability found in cast-iron boilers.