Technical Publication

9
4. Refrigerant Quantity Adjustment. All residential R-410A outdoor units are factory charged for 15 feet
(4.6 m) of line set.
To calculate the initial amount of extra refrigerant (in ounces):
a. Subtract 15 feet (4.6 m) from the total linear (not equivalent) length of actual line set
b. Multiply that value by 0.6 (oz. per foot) or 17.0 (g per meter) of R-410A refrigerant
c. This will be the initial amount of R-410A refrigerant that must be added prior to final
charge adjustment.
All systems must have final charge adjustment performed as required in Section 1. In most residential
applications a minimal amount of additional refrigerant will be needed to account for the volume in the
suction line. For some applications using 1 1/8” suction line and/or over 150 feet of lineal length (45.7 m),
approximately 3 pounds (1.4 kg) of additional refrigerant may be needed to account for the suction line.
For a more precise calculation of refrigerant needs use Table 5-3. The additional refrigerant for given line
lengths can be found in Table 5-4.
R
A
(oz.) = (L
A
- 15) ft. x 0.6 oz./ft.
R
A
( g ) = (L
A
- 4.6) m. x 55.8 g/m.
Where:
R
A
= Initial additional refrigerant needed
L
A
= Actual lineal line set length
Additional Refrigerant
(oz. per lineal foot)
3/8” liquid only 0.60 55.8
3/8” liquid and 5/8” suction 0.63 58.6
3/8” liquid and 3/4" suction 0.67 62.3
3/8” liquid and 7/8” suction 0.74 68.8
3/8” liquid and 1 1/8” suction 0.78 72.5
Line set sizes
Additional Refrigerant
(g. per lineal meter)
Table 5-5 Additional Refrigerant Per Unit Length.
25 50 75 100 125 150 175
3/8" liquid line only
15 30 45 60 75 90 105
3/8" liquid line & 5/8" suction line
16 32 47 63 79 95 110
3/8" liquid line & 3/4" suction line
17 34 50 67 84 101 117
3/8" liquid line & 7/8" suction line
18 35 53 70 88 105 123
3/8" liquid line & 1-1/8" suction line
20 39 59 78 98 117 137
Additional lineal line length over 15 feet
Initial refrigerant addition (oz.)
Table 5-6 Initial Refrigerant for Given Line Length (feet)
7.6 15.222.930.538.145.753.3
3/8" liquid line only 0.4 0.9 1.3 1.7 2.1 2.6 3
3/8" liquid line & 5/8" suction line 0.5 0.9 1.3 1.8 2.2 2.7 3.1
3/8" liquid line & 3/4" suction line 0.5 1 1.4 1.9 2.4 2.9 3.3
3/8" liquid line & 7/8" suction line 0.5 1 1.5 2 2.5 3 3.5
3/8" liquid line & 1-1/8" suction line 0.6 1.1 1.7 2.2 2.8 3.3 3.9
Additional lineal length over 4.6 meters
Initial refrigerant addition (kg)
Table 5-7 Initial Refrigerant for Given Line Length (meters)