Hi Robert,
As stated in the QSG the standard mounting recommendation is for the T310c/d (omni) AP to be mounted horizontally 'dome down' (parallel to the ground).
However; as BeamFlex+ has vertically and horizintally polarised antennas; it is also possible to install the AP vertically, IF this suits the deployment type, as it will not give equivalent coverage to a horizontal deployment.
There is no specified recommended height for installation, as this is dependent on the use-case in your deployment. The distance to the client devices you are connecting is the primary consideration factor.
HTH.
Regards,
Darrel.
