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Specifications subject to change without notice. 38MGR-04SM
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 25 ft. (7.6 m)
per number of zones. For runs over 25 ft. (7.6 m), consult the Long Line Application section on this page for 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 36in (914 mm) should be buried. Provide a
minimum 6in (152 mm) vertical rise to the service valves to prevent refrigerant migration.
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 tubing so vibration or noise is not
transmitted into the structure.
IMPORTANT: Both refrigerant lines must be insulated separately.
Table 21 displays the following maximum lengths allowed.
Table 21 — Piping and Refrigerant
NOTE: The refrigerant charge included is adequate for the outdoor unit’s maximum number of zones multiplied by the
standard piping length per zone. For piping runs greater than the “Maximum Piping Length with no additional
refrigerant charge per System,” see Additional Charge Table Per Zone (Table 22).
Long Line Applications,:
1. No change in line sizing is required.
2. Add refrigerant per Table 22.
Table 22 — Additional Charge Table Per Zone
Additional Refrigerant Calculation
Sum Total Liquid Pipe ft. (m) - Additional Charge Required After ft. (m.) x Additional Charge oz./ft. (g/m) 0.16 (15)
NOTES:
If the calculation results in a negative number no additional refrigerant is required. Electronic expansion valves in the outdoor unit are
used as metering devices.
SYSTEM SIZE
18K
24K
30K
36K
48K
Piping
Min. Piping Length per each indoor unit
ft. (m)
10 (3)
10 (3)
10 (3)
10 (3)
10 (3)
Standard Piping Length per each indoor
unit
ft. (m)
25 (7.5)
25 (7.5)
25 (7.5)
25 (7.5)
25 (7.5)
Max. outdoor-indoor height difference
(OU higher than IU)
ft. (m)
49 (15)
49 (15)
49 (15)
49 (15)
65 (20)
Max. outdoor-indoor height difference
(IU higher than OU)
ft. (m)
49 (15)
49 (15)
49 (15)
49 (15)
65 (20)
Max. height different between indoor
units
ft. (m)
32 (10)
32 (10)
32 (10)
32 (10)
32 (10)
Max. Length per each indoor unit
ft. (m)
82 (25)
98 (30)
115 (35)
115 (35)
115 (35)
Max. Piping Length with no additional
refrigerant charge per System (Standard
Piping length x No. of Zones)
ft. (m)
49 (15)
74 (22)
98 (30)
98 (30)
123 (37.5)
Total Maximum Piping Length per
system
ft. (m)
131 (40)
197 (60)
263 (80)
328 (100)
328 (100)
Additional refrigerant charge
(between Standard – Max piping length) Oz/ft (g/m)
0.16 (15)
0.16 (15)
0.16 (15)
0.16 (15)
0.16 (15)
Suction Pipe (size - connection type)
in
3/8*2
3/8*3
1/2 *1+ 3/8*3 1/2 *1+ 3/8*3 1/2 *2+ 3/8*3
(mm)
9.52*2
9.52*3
12.7*1+9.5*3 12.7*1+9.5*2 12.7*2+9.5*3
Liquid Pipe (size - connection type)
in
1/4*2
1/4*3
1/4*4
1/4*4
1/4*5
(mm)
6.3*2
6.3*3
6.3*4
6.3*4
6.3*5
Refrigerant
Refrigerant Type
R410A
Heat Pump Models Charge Amount
Lbs (kg)
4.41 (2.0)
6.17 (2.8)
6.61 (3.0)
10.14 (4.6)
10.14 (4.6)
Unit Size
No. of Zones
Charge oz. (kg.)
Additional Charge
Required After ft. (m)
Additional Charge
oz./ft. (g/m)
Total Maximum
Piping Length ft. (m.)
18
2
70.55 (2.0)
49 (15)
0.16 (15)
131 (40)
24
3
98.76 (2.8)
74 (22.5)
0.16 (15)
197 (60)
30
4
105.82 (3.0)
98 (30)
0.16 (15)
263 (80)
36
4
162.26 (4.6)
123 (37.5)
0.16 (15)
328 (100)
48
5
162.26 (4.6)
123 (37.5)
0.16 (15)
328 (100)