What must determine the maximum length of a dryer exhaust duct exceeding 35 feet?

The maximum length of a dryer exhaust duct exceeding 35 feet must be determined by the manufacturer's instructions. This is crucial because different dryer models have specific designs and performance capabilities, which include limitations on duct length to ensure proper airflow and effective moisture and lint removal. Exceeding the recommended duct length can lead to reduced efficiency, increased drying times, and potential safety hazards such as lint buildup that can cause a fire.

Manufacturer's instructions are based on testing and standards that indicate how the dryer performs optimally. These guidelines take into account factors like duct diameter, the number of bends in the duct, and the type of material used for the ducting, all of which can affect performance. Therefore, referencing the manufacturer's instructions is essential for safe and efficient dryer operation, particularly for longer exhaust ducts.

While state regulations, local building codes, and inspection guidelines are all important considerations in the installation and maintenance of dryers and their exhaust systems, they typically do not override the manufacturer’s specifications, which are tailored specifically to the appliance in question.