What is the importance of sealing all joints in a mechanical draft system?

Sealing all joints in a mechanical draft system is critical to prevent air leakage, which directly impacts the overall efficiency of the system. When joints are not properly sealed, conditioned air can escape and unwanted air can enter the system, leading to a loss of efficiency in both heating and cooling processes. This not only makes the system work harder to maintain the desired temperature but also increases energy consumption and costs. Furthermore, proper sealing helps maintain the proper pressure within the system, ensuring that it operates as designed and effectively removes combustion byproducts or other exhaust gases.

The other options, while they may have some relevance in broader contexts, do not address the primary function of sealing joints in contributing to the energy efficiency and operational integrity of a mechanical draft system. Flexibility in installation, lifespan, and installation costs, while important considerations, are secondary to the fundamental role of ensuring that air flows correctly through a sealed system.