15
REFRIGERANT LINES
General refrigerant line sizing:
1 The 38MFC/MFQ 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.
IMPORTANT:
Both refrigerant lines must be insulated
separately.
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The following maximum lengths are allowed:
REFRIGERANT LINE LENGTHS ft. (m)
Unit Size
Max Line Length
Max Elevation
(ID over OD)
Max Elevation
(OD over ID)
9K
65 (20)
25 (8)
25 (8)
12K
65 (20)
25 (8)
25 (8)
17K HP
65 (20)
30 (10)
30 (10)
18K AC
65 (20)
30 (10)
30 (10)
22K
98 (30)
30 (10)
30 (10)
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The following are the piping sizes.
PIPE SIZES (in)
Unit Size
Mix Phase
Vapor
9K
1/4
3/8
12K
1/4
1/2
17K HP
1/4
1/2
18K AC
1/4
1/2
22K
3/8
5/8
Refrigerant Charge
REFRIGERANT CHARGE lb. (kg)
Unit Size
Air Conditioner (AC)
Heat Pump (HP)
9K
1.34 (0.61)
2.60 (1.18)
12K
1.43 (0.65)
2.60 (1.18)
17K HP
NA
2.87 (1.30)
18K AC
1.87 (0.85)
NA
22K
2.60 (1.18)
3.52 (1.60)
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Above charge is for piping runs up to 25 ft. (7.6 m).
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For piping runs greater than 25 ft. (7.6 m), add
refrigerant up to the allowable length as specified
below:
ADDITIONAL REFRIGERANT CHARGE
Unit Size
oz./ft. (g/m)
9K --- 18K
0.16 (15)
22K
0.32 (30)
S
Capillary tubes in outdoor unit are used as metering
devices.
Long Line Applications, 38MFC Units:
1 No change in line sizing is required.
2 Add refrigerant per table below.
ADDITIONAL CHARGE TABLE
Unit
Size
Total Line
Length ft
Additional Charge, oz/ft.
ft (m)
Min
Max
10 --- 25
(3 --- 8)
>25 --- 65
(8 --- 20)
>65 --- 98
(20 --- 30)
9K
10
65
None
0.16
12K
18K AC
17K HP
22K
98
0.32
0.32
3 Reduction in capacity due to long lines can be calculated
from the chart below.
CAPACITY LOSS
Capacity,% Loss
Line Length ft (m)
Cooling:
25 (7.5)
33 (10)
49 (15)
65 (20)
98(30)
9&12K
1%
2%
5%
7%
---
18&22K
1%
2%
4%
6%
8%
Heating:
9&12K
1%
2%
7%
11%
---
17&22K
1%
2%
6%
10%
15%
SYSTEM EVACUATION AND
CHARGING
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage or improper operation.
Never use the system compressor as a vacuum pump.
CAUTION
!
Refrigerant tubes and indoor coil should be evacuated using the
recommended deep vacuum method of 500 microns. The alternate
triple evacuation method may be used if the procedure outlined
below is followed. Always break a vacuum with dry nitrogen.
SYSTEM VACUUM AND CHARGE
Using Vacuum Pump
1 Completely tighten flare nuts A, B, C, D, connect manifold
gage charge hose to a charge port of the low side service
valve. (See Fig. 12.)
2 Connect charge hose to vacuum pump.
3 Fully open the low side of manifold gage. (See Fig. 13)
4 Start vacuum pump
5 Evacuate using either deep vacuum or triple evacuation
method.
6 After evacuation is complete, fully close the low side of
manifold gage and stop operation of vacuum pump.
7 The factory charge contained in the outdoor unit is good for
up to 25 ft. (8 m) of line length. For refrigerant lines longer
than 25 ft (8 m), add refrigerant as specified in the
ADDI-
TIONAL REFRIGERANT CHARGE
table in this document.
8 Disconnect charge hose from charge connection of the low
side service valve.
9 Fully open service valves B and A.
10 Securely tighten caps of service valves.
