Which of the following locations is prohibited for fuel-fired appliances to obtain combustion air from?

Fuel-fired appliances must have a safe and reliable source of combustion air for proper operation, efficiency, and safety. The correct answer indicates that storage closets are not appropriate locations for these appliances to obtain combustion air. This is primarily to prevent the accumulation of flammable materials or hinder proper airflow, which could lead to hazardous conditions.

Storage closets often contain items that can obstruct air intake or could potentially catch fire, leading to an increase in risk for fire and asphyxiation due to inadequate ventilation. The International Mechanical Code emphasizes ensuring adequate ventilation where fuel-fired appliances are installed, and storage closets are typically too enclosed to provide the necessary airflow.

In contrast, locations like dining rooms, living rooms, and basements may provide more appropriate conditions for combustion air supply, assuming they meet the specific ventilation requirements outlined in the code. These areas are usually less likely to have blocks to airflow and can provide adequate air for combustion to take place safely.