When planning the ducting for your vent hood, consult the Installation Instructions for your model.
For maximum performance, keep the duct straight and short.
In the past, installation instructions came with a chart outlining the "equivalent vent length." With exhausting, performance diminishes along a curve as the equivalent duct length increases. Each installation and cooking situation is unique, and it is impossible to determine what an "acceptable" level of diminishment is. Therefore, we provide the general guidance of using the shortest and straightest route possible.