Carrier 38AUD*12 Series, Инструкция по установке, запуску и обслуживанию, Страница: 49 / 80

9
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 — 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.
The 38AUD has two separate refrigeration systems. If
required, each circuit will require a field-supplied/installed
supplemental relief device.
Table 3 – Equivalent Lengths for Common Fittings (ft)
Nominal
Tube OD
Elbows
90
°
Std 90
°
Lrad 90
°
Street 45
°
Std 45
°
Street
3
/
8
1.3 0.8 2.2 0.6 1
1
/
2
1.4 0.9 2.3 0.7 1.1
5
/
8
1.6 1 2.5 0.8 1.3
3
/
4
1.8 1.2 2.9 0.9 1.5
7/8
2 1.4 3.2 0.9 1.6
1
1
/
8
2.6 1.7 4.1 1.3 2.1
1
3
/
8
3.3 2.3 5.6 1.7 3
1
5
/
8
4 2.6 6.3 2.1 3.4
2
1
/
8
5 3.3 8.2 2.6 4.5
Nominal
Tube OD
Tees
Branch
Flow
Straight-Thru
No Reduct Reduce 25% Reduce 50%
3
/
8
2.6 0.8 1.1 1.3
1
/
2
2.7 0.9 1.2 1.4
5
/
8
3 1 1.4 1.6
3
/
4
3.5 1.2 1.7 1.8
7/8
4 1.4 1.9 2
1
1
/
8
5 1.7 2.3 2.6
1
3
/
8
7 2.3 3.1 3.3
1
5
/
8
8 2.6 3.7 4
2
1
/
8
10 3.3 4.7 5
CHECK 38AUD UNIT WITH EVAPORATOR COIL
CONNECTIONS — Confirm before installation of unit
that the evaporator coil connections are consistent with
this 38AUD unit.
DETERMINE REFRIGERANT LINE SIZES — Select
the recommended line sizes for the 38AUD unit. See
Tables 3 and 4.
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.
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 (meters [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 4 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 5 for maximum suction tube size for 38AUD
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.
38A
U
D