Hello, 

We recently started using Surpad with our FOIF A90 GNSS.
I set up our coordinate system in the software (NAD83 Tennessee) and loaded in the geoid for our area (Geoid 18 Grid 7 for the USA). 
When measuring a point our Horizontal is correct but the elevation is around 100 feet off compared to what we usually use. I think it is showing ellipsoidal height and not orthometric. 
I am not seeing a place to define any vertical datum.
Is there a step I am missing or is there a way to show orthometric/ confirm that it is showing orthometric height?
Thank you!