7
Suction Lines
Note: If the suction line must rise to the point higher
than the suction connection on the evaporator, a suction
line trap at the outlet of the evaporator must be provided.
Horizontal suction lines should slope away from the
evaporator toward the compressor at the rate of 1/4” per
10 feet for good oil return.
Suction lines that are outside of refrigerated space must
be insulated. See “Line Insulation” for more information.
Suction Line Risers
Note: To provide proper oil return, a suction trap must
be provided at the base of all suction risers.
Prefabricated wrought copper traps are available, or
a trap can be made by using two street ells and one
regular ell. The suction trap must be the same size as
the suction line. For long vertical risers, additional traps
may be necessary. Generally, one trap is recommended
for each length of pipe (approximately 20 feet) to insure
proper oil movement. See Figure 5 below for methods of
constructing proper suction line P-traps.
Figure 5. Suction P-traps
Condensate Drain Lines
Copper drain lines should be used and properly protected
from freezing. In running drain lines, provide a minimum
of 1/4 inch per foot pitch for proper drainage. Drain lines
should be at least as large as the evaporator drain connec-
tion. All plumbing connections should be made in ac-
cordance with local plumbing codes. All condensate drain
lines must be trapped, and run to an open drain. They must
never be connected directly to the sewer systems. Traps in
the drain line must be located in a warm ambient. See Fig-
ure 6. We recommend a trap on all evaporators. Traps lo-
cated outside, or extensive outside runs of drain line must
be wrapped with a drain line heater. The heater should be
connected so that it is continuously on. The drain line must
be insulated to prevent heat loss. A heat input of 20 watts
per lineal foot of drain line for 0ºF (-18°C) room applica-
tions and 30 watts per lineal foot for -20°F (-29°C) rooms
is satisfactory. Inspect the drain pan periodically to insure
free drainage of condensate. If the drain pan contains
standing water, check for proper installation. The drain pan
should be cleaned regularly with warm soapy water.
WARNING: All power must be disconnected before
cleaning. The drain pan also serves as cover for hazardous
moving parts. Operation of unit without drain pan consti-
tutes a hazard.
Refrigeration Piping
Figure 6. Drain Line
Note: Always trap drain lines individually to prevent
vapor migration.