Which failure mode can lead to a loss of heating efficiency in gas heating systems?

The correct answer highlights the issue of deteriorated duct insulation. In gas heating systems, the ductwork is crucial for transporting heated air throughout a building. If the insulation on these ducts becomes worn or damaged, it can lead to heat loss as the warm air travels through the uninsulated or poorly insulated sections. This results in a significant drop in overall heating efficiency because more energy is required to maintain the desired temperature within the living space, ultimately leading to increased energy costs and reduced comfort.

Addressing duct insulation is essential in maintaining the efficacy of heating systems, as proper insulation not only helps retain heat but also aids in consistent airflow and balanced heating. This focus on insulation is necessary for optimizing the performance of a gas heating system.