Which two factors determine the efficiency of a distribution system?

The efficiency of a distribution system is primarily determined by how effectively it delivers heat to the intended spaces and the losses that occur within the system. Efficient heat delivery means that the system is able to convey thermal energy from the source (such as a furnace or boiler) to the rooms without unnecessary waste. This includes factors like appropriate temperature settings, air flow management, and insulation of the ductwork.

System losses encompass any heat that is lost due to various factors, such as heat escaping through uninsulated ducts, leakage, or inefficiencies in the design of the system itself. By minimizing these losses and maximizing the effectiveness of heat delivery, a distribution system can operate at a higher level of efficiency, ultimately leading to better energy use and cost savings for the homeowner.

Other options focus on aspects that, while relevant, do not directly address the core factors affecting distribution system efficiency as thoroughly as heat delivery and system losses do.