Which of the following is NOT a characteristic of efficient heating appliances?

The characteristic that is not associated with efficient heating appliances is the aspect of having proportionally small exterior surfaces. Efficient heating appliances typically have larger exterior surfaces to facilitate effective transfer of heat to the surrounding environment. A larger surface area can improve the ability to radiate or convect heat, contributing to overall efficiency.

In contrast, rapid heat transfer through the walls, adequate turbulence inside the appliance, and effective air movement outside are all crucial to ensuring that heat is distributed efficiently and effectively. Rapid heat transfer enhances the appliance's ability to deliver warmth to the space quickly. Adequate turbulence helps mix the air within the appliance, allowing for more uniform heating and better fuel combustion. Lastly, effective air movement (convection) outside the appliance helps to circulate warm air throughout the living space, maximizing the thermal comfort provided by the heating system.