General Refrigerant Line Sizing; Piping And Refrigerant Information; Long Line Applications; Refrigerant Lines - Carrier 38MHRB series Service Manual

REFRIGERANT LINES

General Refrigerant Line Sizing

1 The outdoor units are shipped with a full charge of R410A
refrigerant. All charges, line sizing, and capacities are based
on runs of 25ft. (7.6 m). For runs over 25 ft. (7.6 m),
consult the long−line applications section for the proper
charge adjustments.
2 The minimum refrigerant line length between the indoor
and outdoor units is 10 ft. (3 m).
3 Refrigerant lines should not be buried in the ground. If it is
necessary to bury the lines, not more than 36 in (914 mm)
should be buried. Provide a minimum 6in (152 mm)
vertical rise to the service valves to prevent refrigerant
migration.
Table 12 lists the maximum lengths allowed.
System Size
Min. Piping Length
Standard Piping Length
Max. outdoor-indoor
height difference
(OU higher than IU)
Max. outdoor-indoor
height difference
(IU higher than OU)
Max. Piping Length with
no additional refrigerant
charge per System
Piping
(Standard Piping length)
Total Max. Piping
Length per system
Additional refrigerant
charge (between Standard
– Max piping length)
Suction Pipe
(size - connection type)
Liquid Pipe
(size - connection type)
Refrigerant Type
Cooling Only Models
Charge Amount
Refrigerant
Heat Pump Models
Charge Amount

Long Line Applications,:

1 No change in line sizing is required.
2 Add refrigerant per Table 12.
Table 12—Piping and Refrigerant Information
12K (115V) 9K (208-230V)
ft. (m) 10(3)
25(7.5)
ft. (m)
33(10)
ft. (m)
33(10)
ft. (m)
ft. (m) 25(7.5)
ft. (m) 82(25)
Oz/ft (g/m) 0.161(15)
In (mm) 1/2(12.7)
In (mm) 1/4(6.35)
Type R410A
Lbs (kg) 1.30(0.59)
Lbs (kg) 2.12(0.96)
4 Both lines must be insulated. Use a minimum of 1/2in.
(12.7 mm) thick insulation. Closed−cell insulation is
recommended in all long−line applications.
5 Special consideration should be given to isolating
interconnecting tubing from the building structure. Isolate
the the tubing so vibration or noise is not transmitted into
the structure.
IMPORTANT: Both refrigerant lines must be insulated
separately.
12K (208-230V)
10(3) 10(3)
25(7.5) 25(7.5)
33(10) 33(10)
33(10) 33(10)
25(7.5) 25(7.5)
82(25) 82(25)
0.161(15) 0.161(15)
3/8(9.52) 1/2(12.7)
1/4(6.35) 1/4(6.35)
R410A R410A
N/A 1.17 (0.53)
1.76(0.8) 2.12(0.96)
18
18K (208-230V) 24K (208-230V)
10(3) 10(3)
25(7.5) 25(7.5)
66(20) 66(20)
66(20) 66(20)
25(7.5) 25(7.5)
98(30) 164(50)
0.161(15) 0.322(30)
1/2(12.7) 5/8(15.9)
3/8(9.52)
1/4(6.35)
R410A R410A
1.98 (0.9) 2.56 (1.16)
2.82 (1.28) 3.97 (1.8)