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faces, plywood sheets may be placed against the sides of the
unit, behind cables. Run cables to a central suspension point so
that the angle from the horizontal is not less than 45 degrees.
Raise and set the unit down carefully.
If it is necessary to roll the unit into position, mount the unit on
longitudinal rails, using a minimum of 3 rollers. Apply force to
the rails, not the unit. If the unit is to be skidded into position,
place it on a large pad and drag it by the pad. Do not apply any
force to the unit.
Raise from above to lift the unit from the rails or pad when unit
is in its final position.
After the unit is in position, remove all shipping materials and
top crating.
Step 5 — Complete Refrigerant Piping
Connections
IMPORTANT: Do not bury refrigerant piping underground.
IMPORTANT: A refrigerant receiver is not provided with
the unit. Do not install a receiver.
PROVIDE SAFETY RELIEF — The 38AU unit is provided
with a fusible joint in the suction line in accordance with
applicable UL standards for pressure relief. If local codes
dictate an additional safety relief device, purchase locally and
install locally. Installation will require the recovery of the
factory shipping charge before the factory tubing can be cut
and the supplemental relief device is installed.
Model 38AUD has two separate refrigeration systems. If
required, each circuit will require a field-supplied/installed
supplemental relief device.
Table 4 — Equivalent Lengths for Common Fittings (ft)
Nominal
Tube OD
90° Std
90° Lrad 90° Street
3
/
1.3
0.8
8
1
/
1.4
0.9
2
5
/
1.6
1
8
3
/
1.8
1.2
4
7/
2
1.4
8
1
1
/
2.6
1.7
8
3
1
/
3.3
2.3
8
5
1
/
4
2.6
8
1
2
/
5
3.3
8
Nominal
Branch
Tube OD
Flow
No Reduct
3
/
2.6
0.8
8
1
/
2.7
0.9
2
5
/
3
1
8
3
/
3.5
1.2
4
7/
4
1.4
8
1
1
/
5
1.7
8
3
1
/
7
2.3
8
1
5
/
8
2.6
8
1
2
/
10
3.3
8
Elbows
45° Std
45° Street
2.2
0.6
1
2.3
0.7
1.1
2.5
0.8
1.3
2.9
0.9
1.5
3.2
0.9
1.6
4.1
1.3
2.1
5.6
1.7
3
6.3
2.1
3.4
8.2
2.6
4.5
Tees
Straight-Thru
Reduce 25% Reduce 50%
1.1
1.3
1.2
1.4
1.4
1.6
1.7
1.8
1.9
2
2.3
2.6
3.1
3.3
3.7
4
4.7
5
CHECK 38AU MODEL WITH EVAPORATOR COIL CON-
NECTIONS — Confirm before installation of unit that the
evaporator coil connections are consistent with this 38AU
model. See Table 3 on page 9.
DETERMINE REFRIGERANT LINE SIZES — Select the
recommended line sizes for 38AUZ and 38AUD unit from the
appropriate tables.
Determine the linear length of interconnecting piping required
between the outdoor unit and indoor unit (evaporator).
Consider and identify also the arrangement of the tubing path
(quantity and type of elbows in both lines), liquid line solenoid
size, filter drier and any other refrigeration specialties located
in the liquid line. Refer to the indoor unit installation
instructions for additional details on refrigeration specialties
devices.
Determine equivalent line length adjustments for path and
components and add to linear line lengths. See Table 4,
Equivalent Lengths for Common Fittings, for usual fitting
types. Also identify adjustments for refrigeration specialties.
Refer to Part 3 of the Carrier System Design Manual for
additional data and information on equivalent lengths.
NOTE: Equivalent line lengths will vary based on tube
diameter. Calculate equivalent line length for each pipe by
adding equivalent length adjustments to linear lengths for
each pipe.
Enter the appropriate table to select the recommended line
sizes.
Model:
38AUZ
38AUD
Liquid Lift – A liquid lift condition exists when the outdoor
unit is located below the indoor (evaporator) unit and liquid
flows vertically up in a portion of the liquid line. The vertical
column of liquid reduces the available state point subcooling at
the evaporator coil's thermal expansion valve. This effect
reduces the length of liquid lift (feet of elevation) that a liquid
line size can accommodate. Longer linear tube lengths will also
reduce the amount of liquid lift possible.
Check Tables 5 (38AUZ) and 6 (38AUD) for maximum liquid
lift capabilities for line sizes. Reselect the liquid line tube size if
necessary. If maximum available tube size cannot provide the
required lift distance on this installation, relocate the outdoor
unit to reduce the equivalent line length or the lift requirement.
Suction Riser – A suction riser condition exists when the
outdoor unit is located above the indoor (evaporator) unit and
suction vapor must flow vertically up to return to the
compressor. Oil return is a concern when the suction tube size
is too large to produce the minimum refrigerant velocity to
ensure oil return at minimum load conditions.
Check Table 7 for maximum suction tube size for 38AU units
at minimum load conditions. Consider suction speed riser
(reduced tube size for vertical segment only) or double suction
riser arrangement if the recommended suction tube size does
not provide necessary minimum flowrates for this riser.
10
Line Sizes Table Quantity of Line Sets
5
1
6
2
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