Where must the controls, combustion air inlets, and draft hoods for duct furnaces be located?

The correct response indicates that controls, combustion air inlets, and draft hoods for duct furnaces must be located outside of the ducts. This positioning is crucial for several reasons.

First, placing the combustion air inlets outside of the ducts ensures that the furnace has access to fresh air needed for efficient combustion. Fresh combustion air is vital for preventing issues like incomplete combustion, which can lead to decreased efficiency and increased emissions. By having the inlets located outside, the system can effectively draw in the proper amount of air, regardless of the conditions within the ducts themselves.

Additionally, having the controls located outside the ducts enhances accessibility and safety. Maintenance personnel can easily reach and operate these controls without needing to enter potentially confined or hazardous spaces. This arrangement also provides better visibility for monitoring the system's operation, making troubleshooting easier when necessary.

Moreover, draft hoods need to be situated outside the ducts to function correctly in facilitating the safe exit of combustion gases. This positioning aids in maintaining proper airflow and draft, ensuring that harmful gases are vented out of the system efficiently.

In summary, placing the controls, combustion air inlets, and draft hoods outside of the ducts supports safety, efficiency, and maintainability of duct furnaces, making this choice the best