The “official support” for the Econet vent is not completely functional as currently posted - the On/Off icon never changes, some poll() commands will not retrieve the current level, and the device does not report/acknowledge changes from the setLevel() command.
This latter one is problematic if you are try to control the vent, but want to check its current setting (switch.currentLevel) before sending a new one because the vent has to calibrate itself (cycle the damper full open/full close) before setting an actual level.