Open Studio: unable to add the setpoint manager Humidity minimum to my airloop since that setpoint manager does not exist.

edit

It seems like it was indeed meant to be added to hvac_library.osm but was forgotten.

I opened an issue on Github: Issue#3130 and I just fixed it in PR#3131. It should get merged in soon and be available in the next OpenStudio version or shortly thereafter.

If you want a quick fix, you can head over to your local copy of hvac_library.osm (on Windows that's something like C:\openstudio-x.y.z\Resources\default\hvac_library.osm), open it up, and paste the following snippet:

OS:SetpointManager:SingleZone:Humidity:Minimum, 
  {3beb4328-e84f-4368-9105-1071d292ebe3}, !- Handle 
  Setpoint Manager Single Zone Humidity Minimum, !- Name 
  MinimumHumidityRatio,                   !- Control Variable 
  ,                                       !- Setpoint Node or NodeList Name 
  ;                                       !- Control Zone Name

I doubt you'd have a handle conflict, but to make sure do a search for {3beb4328-e84f-4368-9105-1071d292ebe3} in the entire file, you should find only one occurrence: the one you added.

Then relaunching the OS App, you should now be able to drag and drop this SetpointManager.