Refrigerant Lines - Carrier High Wall Duct Free Split System 38MVC Service Manual

REFRIGERANT LINES

General refrigerant line sizing:
1. The 38MVC/MVQ 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). For runs over 25 ft (7.6
m), consult long- -line section on this page for proper charge
adjustments.
2. 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 6- -in (152 mm)
vertical rise to the service valves to prevent refrigerant
migration.
4. Both lines must be insulated. Use a minimum of 1/2- -in.
(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 that vibration or noise is not transmitted into
the structure.
S The following maximum lengths are allowed:
REFRIGERANT LINE LENGTHS ft. (m)
Max Line
Unit Size
Length
9K 65 (20)
12K 65 (20)
18K 100 (30)
24K 100 (30)
S The following are the piping sizes.
PIPE SIZES
Unit Size Mix Phase
9K
12K
18K
24K
Refrigerant Charge
REFRIGERANT CHARGE lb. (kg)
Unit Size Air Conditioner
9K 2.3 (1.0)
12K 2.9 (1.3)
18K 4.4 (2.0)
24K
S Above charge is for piping runs up to 25 ft. (7.6 m).
S For piping runs greater than 25 ft. (7.6 m), add 0.1 oz. of
refrigerant per foot of extra piping up to the allowable
length.
Max Elevation Max Elevation
(ID over OD) (OD over ID)
35 (11) 35 (11)
35 (11) 35 (11)
50 (15) 50 (15)
60 (18) 60 (18)
Vapor
1/4" 3/8"
1/4" 1/2"
1/4" 1/2"
3/8" 5/8"
Heat Pump
2.4 (1.1)
3.0 (1.4)
TBD
TBD TBD
Long Line Applications, 38MVC Units:
1. A crankcase heater should be added for line lengths longer
than 25 ft (7.62 m) to prevent the migration of refrigerant to
the compressor during the "OFF" cycle.
2. A field fabricated wind baffle is recommended.
3. No change in line sizing is required.
4. Add refrigerant per table below.
ADDITIONAL CHARGE TABLE
Total
Line Length,
Unit
ft
Size
10 --- 25 ft
Min. Max.
(3.05 --- 7.62m)
9K
cool
only
9K
hp
65
12K
cool 10 none
only
12K
hp
18K
cool 100
only
5. Reduction in capacity due to long lines can be calculated
from the chart below.
CAPACITY LOSS
Capacity, % Loss
Cooling:
9 & 12 KBTU/H models
18 & 24 KBTU/H models
Heating:
9 & 12 KBTU/H models
18 & 24 KBTU/H models
18
Additional Charge, oz.
>25 --- 65 ft >65 --- 100 ft
(7.62---19.81m) (19.81---30.48m)
0.1 oz per
foot
0.1 oz. per
foot
Line Length, ft
25 45 65 100
0% 2% 5%
0% 2% 4% 7%
0% 7% 11%
0% 7% 11% 15%