What characteristic defines a high heat appliance?

A defining characteristic of a high heat appliance is that the products of combustion exceed 2,000°F at the flue entrance. This high temperature indicates that the appliance is capable of operating at very high heat levels, which is crucial for applications such as industrial processes or specific heating needs in commercial settings. The materials and construction of high heat appliances are designed to withstand these elevated temperatures, ensuring safety and efficiency in their operation.

In contrast, operating at less than 1,000°F does not meet the criteria of being classified as a high heat appliance. While natural gas may be a fuel source for some appliances, it is not a definitive characteristic for identifying high heat appliances since they can also operate on other fuel types. Additionally, the specification for residential use does not inherently define high heat appliances, as they can be used in various contexts, including commercial and industrial environments.