Which of the following describes the construction of convection appliances?

The construction of convection appliances is characterized by a double wall designed to facilitate air circulation. This double-wall design allows for air to flow between the two walls, enhancing the efficient distribution of heat throughout the space. The additional air pocket created by the double walls not only helps in maintaining even heat distribution but also increases safety by keeping the outer surface cooler to the touch. This is particularly important in residential settings where safety and comfort are paramount when operating a heating appliance.

In contrast, single-wall constructions, while simpler, do not provide the same efficiency in heat circulation and can become quite hot, posing a burn risk. All-metal construction, while relevant for durability, does not specifically describe the convection aspect that focuses on air circulation. Similarly, a glass front is often included for aesthetic purposes and is not a defining feature of how convection appliances work. Hence, the choice focused on the double wall accurately reflects the intended design and function of convection appliances.