Decide where you need your diverter. Open the main branch’s duct at a joint, when possible, and remove a duct section that’s as long as the diverter.
Cut the duct if necessary. Most diverter units connect with a slip-in, bolted flange or round collar/clamp connector, but there are other methods for custom connections.
Your diverter unit should have the same shape, size and type of connector as the rest of your ductwork. If you must cut the duct, install a matching connector on the remaining duct.
Mount the diverter in the open main duct. Connect each end of the diverter to the duct and seal the connections as appropriate for your connection system.
If your unit is an automatic diverter, connect the appropriate electric, pneumatic or hydraulic actuator to the diverter’s actuating lever.
Extend the alternate branch duct to the remaining outlet on the diverter unit. Connect the alternate branch duct to the diverter unit and seal the connection.
Check for correct diverter valve operation. Check airflow diversion when the HVAC system is running.