Carrier 38AUD*12 Series, Installation, Start-Up And Service Instructions Manual, Page: 50 / 80

10
Table 4 – 38AUD 15-25 Piping Recommendations (Two-Circuit Unit)
SI
NOTE
: 38AUD requires TWO sets of refrigeration piping
R-410A
Equivalent
Length m
0-12 12-23 23-34 34-46 46-57
Model
Linear
Length m
0---7.5 7.5---15 15---23 23---30 30---38
38AUD*16
Liquid Line
3
/
8
3
/
8
3
/
8
1
/
2
3
/
8
1
/
2
1
/
2
Max Lift 7.5 15 22 23 13 30 38
Suction Line
7
/
8
7
/
8
1
1
/
8
1
1
/
8
1
1
/
8
Charge (kg) A/B 5.9 6.3 7.0 8.0 7.5 8.9 9.8
38AUD*25 Liquid Line
1
/
2
1
/
2
1
/
2
1
/
2
5
/
8
1
/
2
5
/
8
Max Lift 7.5 15 23 20 28 23 33
Suction Line
7
/
8
1
1
/
8
1
1
/
8
1
1
/
8
1
3
/
8
Charge (kg) A/B 9.4 10.3 11.2 12.1 13.8 13.0 15.1
English
NOTE
: 38AUD requires TWO sets of refrigeration piping
R-410A Equivalent
Length
ft 0---12 38---75 75---113 113---150 150---188
m 0---7.5 7.5---15 15---23 23---30 46-57
Model Linear
Length ft
0---25 25---50 50---75 75---100 100---125
38AUD*16 Liquid Line
3
/
8
3
/
8
3
/
8
1
/
2
3
/
8
1
/
2
1
/
2
Max Lift 25 50 71 75 43 100 125
Suction Line
7
/
8
7
/
8
1
1
/
8
1
1
/
8
1
1
/
8
Charge (lbs) A/B 12.9 13.9 15.4 17.7 16.5 19.6 21.6
38AUD*25 Liquid Line
1
/
2
1
/
2
1
/
2
1
/
2
5
/
8
1
/
2
5
/
8
Max Lift 7.5 15 23 20 28 23 33
Suction Line
7
/
8
1
1
/
8
1
1
/
8
1
1
/
8
1
3
/
8
Charge (lbs) A/B 20.7 22.8 24.7 26.6 30.4 28.6 33.3
Legend:
Equiv Length Equivalent tubing length, including effects of refrigeration specialties devices
Linear Length Typical linear tubing length, (50% added to linear to define Equivalent Length for this table)
Liquid Line Tubing size, inches OD.
Max Lift Maximum liquid lift (indoor unit ABOVE outdoor unit only), at maximum permitted liquid line pressure drop —
S
Linear Length Less than 30 m (100 ft): Minimum 1.1
°
C (2.0
°
F) subcooling entering TXV
S
Linear Length Greater than 30 m (100 ft): Minimum 0.3
°
C (0.5
°
F) subcooling entering TXV
Suction Line Tube size, inches OD
Charge Charge Quantity, kg (lbs). Calculated for both liquid line sizes (where applicable), but only with larger suction line size
(where applicable)
NOTE: For applications with equivalent length greater than 57 m (188 ft) and/or linear length greater than 38 m (125 ft),
contact your local Carrier representative.
Table 5 –
38AUD Maximum Suction Pipe Size
Model: Unit Size Maximum Tube Size
38AUD
16 1
5
/
8
25 1
5
/
8
INSULATE SUCTION LINES — Apply closed-cell
tubular insulation to all suction lines between evaporator
coil connection and 38AUD unit’s suction service valve.
Hot Gas Bypass — Hot gas bypass, if used, should be
introduced before the evaporator. (A bypass route that also
bypasses the evaporator circuit may lead to oil trapping in
the evaporator circuit during low load conditions and then
to oil slugging as evaporator load increases.) Model
38AUD units do not include a hot gas stub connection; a
tee must be field-supplied and installed in the compressor
discharge line. Run a
1
/
2
-in OD line between outdoor unit
and evaporator coil inlet. Install an Auxiliary Side
Connector at the evaporator between TXV and distributor
(follow instructions for the side connector part). Insulate
the hot gas line.
38A
U
D