ITC HD7515 Manuel D'instructions page 9

Unit Installation
Contrary to all other connections in the
piping system, do not glue the last fitting
to the main unit. Our central vacuums
are equipped with an adjustable air intake
valve (figure 2), which does not require
glue. An air-tight fit is obtained with the
screw-type adjustment on the fitting itself.
figure 2
Installation 9