What can happen if a boiler shell is not vented and drained properly?

When a boiler shell is not vented and drained properly, it can lead to significant safety hazards, including the risk of potential leaks and even boiler implosion. Proper venting is essential to ensure that pressure does not build up within the boiler shell. If the pressure exceeds the design limits, there could be catastrophic failures such as the shell collapsing or rupturing.

Additionally, improper drainage can lead to water accumulation within the boiler, which can also create dangerous operating conditions. Water that cannot drain properly can produce steam, increasing internal pressures further and leading to implosion. The structural integrity of the boiler relies on proper maintenance practices, including appropriate venting and draining procedures, to ensure safe and effective operation.

In contrast, the other options suggest outcomes that are either positive or neutral, which do not reflect the serious consequences of inadequate venting and drainage. Increased energy efficiency and pleasant odors are unrealistic in this context, and the notion that the boiler will operate normally contradicts the critical importance of proper maintenance.