Proper fan installation is necessary to optimize performance. The following points outline installation techniques to help achieve optimum performance. For existing construction, depending on the building's structure and the ability to access the ducts, you may not be able to use all of these techniques. However, the more techiques used, the better the performance you can expect from your ventilation fan. In new construction where the walls and ceilings are open, with proper planning, applying these techniques can be relatively easy.
In order to reduce elbows and optimize fan performance, install the fan with the exhaust port pointed in the direction of the termination point. Be sure to use the duct diameter size specified for the selected fan. Reducing the duct diameter (at any point in the duct run) will create substantial static pressure and reduce the fan's performance by as much as 90%.