According to NFPA pamphlet #54, unvented space heaters should not be installed in which type of area?

Unvented space heaters are designed to operate without a dedicated ventilation system, and they release combustion gases directly into the living space. According to NFPA pamphlet #54, installing these heaters in bathrooms is particularly discouraged due to the unique conditions present in such areas. Bathrooms often have higher levels of humidity and moisture, which can lead to the accumulation of combustion byproducts and the increased risk of potential health hazards, such as carbon monoxide buildup.

Additionally, bathrooms are typically small, confined spaces where the possibility of proper air circulation and ventilation is limited. The combination of limited air exchange and the potential for moisture can create an unsafe environment, increasing the risk of fire and health risks associated with the use of unvented heaters. While unvented heaters may sometimes be utilized in broader living spaces, their use in bathrooms presents significant safety concerns which is why this recommendation is emphasized.