Unpack your heater vent kit and inspect the unit. This allows you to readily locate the screw holes along the flanges that stick out from the sides of the heater vent. The flanges have predrilled holes that allow you to quickly and easily mount the heater vent in the space between the wall studs.
Hold the heater vent into place between the wall studs. Set the torpedo level along the top of the vent so you can keep the vent level during installation. With your off hand, hold the vent in place. With your main hand, use the drill to place a screw into one of the predrilled holes in the flange. Screw directly into the wall stud.
Check the levelness of the heater vent with the torpedo level. Adjust the opposite side of the vent from your first screw as necessary to level the vent. Continue holding the heater vent in place while you place another screw through the flange into the wall studs. Remove the torpedo level and finish screwing the rest of the screws into the wall studs through the flange. Let your HVAC specialist connect the ductwork to the vent.