  There is a class of binary post-asymptotic giant branch (post-AGB) stars that
exhibit remarkable near-infrared (NIR) excess. These stars are surrounded by
disks with Keplerian or quasi-Keplerian dynamics and outflows composed of gas
escaping from the rotating disk. Depending on the dominance of these
components, there are two subclasses of binary post-AGB stars: disk-dominated
and outflow-dominated. We aim to properly study the hourglass-like structure
that surrounds the Keplerian disk around 89 Her. We present total-power
on-the-fly maps of $^{12}$CO and $^{13}$CO $J$=2-1 emission lines in 89 Her.
Previous studies are known to suffer from flux losses in the most extended
components. We merge these total-power maps with previous NOEMA maps. The
resulting combined maps are expected to detect the whole nebula extent of the
source. Our new combined maps contain the entirety of the detectable flux of
the source and at the same time are of high spatial resolution thanks to the
interferometric observations. We find that the hourglass-like extended outflow
around the rotating disk is larger and more massive than suggested by previous
works. The total nebular mass of this very extended nebula is 1.8E-2 solar
masses, of which 65% comes from the outflow. The observational data and model
results lead us to classify the envelope around 89 Her as an outflow-dominated
nebula, together with R Sct and IRAS 19125+0343 (and very probably AI CMi, IRAS
20056+1834, and IRAS 18123+0511). The updated statistics on the masses of the
two post-AGB main components reveal that there are two distinct subclasses of
nebulae around binary post-AGB stars depending on which component is the
dominant one. We speculate that the absence of an intermediate subclass of
sources is due to the different initial conditions of the stellar system and
not because both subclasses are in different stages of the post-AGB evolution.
