What is a potential location where combustion air for fuel-fired appliances should not be sourced from?

Fuel-fired appliances require combustion air for efficient operation and safety, and the source of this air can significantly impact the appliances' function. The correct choice of a potential location where combustion air should not be sourced from is storage closets.

Storage closets often contain a variety of materials, including chemicals, flammable items, or even miscellaneous clutter that can obstruct airflow. Utilizing air from these spaces can introduce combustible vapors or contaminants into the combustion process, which poses a safety hazard and can lead to incomplete combustion. This situation could increase the risk of carbon monoxide production and affect the efficiency of the appliance.

In contrast, while sourcing air from hallways, garages, or kitchens may have their own concerns based on specific scenarios or local codes, they're more commonly accepted for providing combustion air in practice, provided that appropriate safety measures are followed. Thus, the consideration of airflow quality and the potential hazards associated with the origin of combustion air make storage closets unsuitable for this purpose.