Which type of heating system is specifically restricted from installation in bathrooms according to NFPA pamphlet #54?

Unvented space heaters are specifically restricted from installation in bathrooms according to NFPA pamphlet #54 due to safety concerns. These types of heaters burn fuel to produce heat, and because they do not have a venting system to exhaust combustion gases outside, they can lead to the accumulation of harmful gases such as carbon monoxide indoors. In a confined space like a bathroom, where ventilation is often limited, this poses a significant health risk to occupants.

The concerns with unvented heaters in bathrooms are particularly acute because bathrooms typically have higher humidity levels, and the presence of moisture can exacerbate issues related to combustion gases. Therefore, to ensure safety and prevent potential hazards, the installation of unvented space heaters is prohibited in such environments.

The other heating system types mentioned may have different safety profiles and regulations. For instance, vented space heaters are designed to safely expel combustion gases outside, making them viable for various indoor settings, including bathrooms. Similarly, radiant heating systems and baseboard heaters do not produce combustion byproducts indoors and thus do not face the same restrictions as unvented space heaters.