Fuel-fired appliances should not obtain combustion air from which of the following locations?

Fuel-fired appliances, such as furnaces, water heaters, or stoves, require a specific amount of air for combustion. When considering the source of combustion air, it is critical to ensure safety and prevent potential hazards like carbon monoxide buildup.

Accessing combustion air from bathrooms is not advisable because these spaces often have limited ventilation. Bathrooms typically have higher humidity as well, which can lead to moisture issues in the appliance and can adversely affect combustion efficiency. The moisture can also lead to corrosion and other problems within the appliance. Furthermore, bathrooms tend to be areas where people spend less time, and an appliance malfunction could go unnoticed much longer than it would in a more frequently used room.

On the other hand, living rooms, bedrooms, and dining rooms are generally more suitable for combustion air sourcing, as they typically have better ventilation and are more frequently monitored for safety concerns. Thus, avoiding combustion air from bathrooms enhances the safety and efficiency of fuel-fired appliances.