Insualation of at least

Insualation of at least 1/2" wall thickness should be used on
the vapor gas line to prevent condensation when cooling and
heat loss when heating. The insulation should be installed
on the tubing prior to installation and should be run the entire
length of the installed line. The end of the tubing over which
the insulation is being slipped should be covered to insure
that no foreign material is introduced to the interior of the
tubing. The outdoor units are equipped with two refrigerant
line service valves, and, as shipped, the valves are in the
front-seated or "down" position.