A down-flow furnace must include temperature control to limit outlet air to what maximum temperature?

The correct answer is based on the guidelines established for down-flow furnaces. For safety and efficiency, a down-flow furnace is designed to limit the temperature of the air that it delivers to the living space. The maximum outlet air temperature set at 200°F is a standard that ensures not only the comfort of the occupants but also protects the furnace system and associated ductwork from overheating, which could lead to damage or hazardous conditions.

Maintaining this maximum temperature helps to prevent burns or discomfort for users and avoids unnecessary stress on the heating system components. Standards such as these are put in place to ensure that any heating system operates safely and effectively within its designed parameters. In this case, limiting the outlet air temperature to 200°F helps balance performance and safety, making it the appropriate temperature control standard.