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17
Step 3 — Make Refrigerant Piping
Connections
The units have large suction lines to minimize friction loss-
es. The units also have the ability to operate at low capacity.
Because of these capabilities, use special care with suction pip-
ing and suction risers to ensure proper compressor oil return
under all operating conditions. If the evaporator is above the
condensing unit, the maximum allowable vertical separation
between the condensing unit and the evaporator is 75 ft
(22.9 m) for all units. Size suction lines in accordance with
Table 7 and Fig. 12.
SIZE REFRIGERANT LINES — Consider the length of pip-
ing required between the condensing unit and indoor unit
(evaporator), the amount of liquid lift, and compressor oil re-
turn. Suction and liquid lines should be sized in accordance
with Table 7. Double suction risers may be required if con-
densing unit is located above the evaporator to assure proper
oil return at minimum load operating conditions. See Table 7
and Fig. 12. Note the indoor unit installtion instructions for ad-
ditional information.
CAUTION
Do NOT bury refrigerant piping underground. Failure to
comply could result in equipment damage.
CAUTION
The field-supplied liquid line solenoid valve must be
installed at the evaporator to avoid possible compressor
damage during unit operation if the maximum allowable
evaporator size is exceeded per Table 8. See Fig. 13 (for
38APD025-100 dual-circuit units), or Fig. 14 (for
38APS025-050 single-circuit units).
Fig. 12 — Double Suction Riser Construction
LEGEND
NOTES:
1. Short riser, pipe D, is used when routing suction line to
condensing unit connection. See table at right.
2. See Table 7 for values of A, B, and C.
A—Pipe A, Suction Riser, without Trap
B—Pipe B, Suction Riser with Trap
C—Suction Line to Condensing Unit
D—Pipe D, Suction Riser Short Lift
RED. — Reducer
STR — Street
38AP
UNIT
SIZE
D PIPE DIAMETER
Dual Circuit
Single Circuit
Circuit A Circuit B
in. mm in. mm in. mm
025 1
1
/
8
29 1
1
/
8
29 1
3
/
8
35
027 1
1
/
8
29 1
1
/
8
29 1
3
/
8
35
030 1
1
/
8
29 1
1
/
8
29 1
3
/
8
35
040 1
3
/
8
35 1
1
/
8
29 1
5
/
8
41
050 1
3
/
8
35 1
3
/
8
35 1
5
/
8
41
060 1
3
/
8
35 1
5
/
8
41 — —
070 1
5
/
8
41 1
5
/
8
41 — —
080 1
5
/
8
41 1
5
/
8
41 — —
090 1
5
/
8
41 1
5
/
8
41 — —
100 1
5
/
8
41 1
5
/
8
41 — —
a38-7132