Which issue is commonly associated with improper ventilation in oil heating systems?

Improper ventilation in oil heating systems often leads to soot buildup and the potential for backdrafts. When ventilation is inadequate, the combustion process is disrupted, causing incomplete burning of the oil. This incomplete combustion results in soot production, which can accumulate within the system and interfere with its efficiency. Additionally, lack of proper airflow can create negative pressure situations where combustion gases, instead of being expelled outside, can flow back into the living space. This poses serious safety risks, including exposure to harmful carbon monoxide.

The other options do not accurately reflect the consequences of insufficient ventilation. Enhanced fuel economy and improved combustion efficiency require adequate airflow to ensure that fuel is burned properly. On the other hand, a reduced risk of explosion is associated with proper ventilation, as good airflow can help mitigate the buildup of flammable gases. Overall, option C effectively captures the primary concerns tied to improper ventilation in oil heating systems.