Which types of heating sources are not permitted in manufactured homes?

The choice indicating that supplementary heat sources not factory installed are not permitted in manufactured homes is correct because these homes are required to adhere to specific safety standards and codes that govern heating systems. Supplementary heating sources that are not factory installed can pose significant risks, such as improper ventilation, excessive heating, and the potential for fire hazards.

Manufactured homes are typically designed and constructed with certain heating systems that are installed at the factory to ensure they meet these safety standards. Any additional heating source that is not integrated into the original design may not have undergone the same testing and certification process, leading to concerns about efficiency and safety.

In contrast, factory-installed heating units are generally accepted as they comply with the necessary building codes and safety regulations, while solar-powered heating systems can be integrated properly if designed for use in manufactured homes.

Thus, the consideration for safety and adherence to established guidelines makes clear why supplementary heat sources that are not factory installed are not permitted.