What defines an appliance's categorization based on the temperature of combustion products?

The categorization of an appliance based on the temperature of combustion products is primarily defined by combustion temperature. This aspect is crucial because the temperature at which the combustion products exit an appliance can determine how it is classified, especially in terms of efficiency, emissions, and safety.

Appliances that operate at higher temperatures typically fall into specific categories that correspond with their design requirements, including venting needs and material tolerances. Additionally, the temperature of combustion products can influence the type of flue system required and dictate installation guidelines due to the risk of heat-related hazards.

While the type of fuel used does play a role in the performance and efficiency of an appliance, it's the actual combustion temperature that is critical for classification. Size and manufacturer specifications are relevant for various operational standards but do not directly relate to how combustion products are categorized in terms of temperature.