Square elbow and wye fittings in Design Master HVAC can have turning vanes inserted on them.
When you manually insert one of these fittings, you will be asked whether they should be inserted. If you want to change this setting for a fitting that already exists, insert the fitting again.
Turning vanes can also be configured to be included on these fittings automatically in the Fittings section of the Options command.
Change the Turning vanes on square elbow and wyes¬†option.
If you change this option in the middle of a project, you will need to redraw the ductwork to have the turning vanes updated.