Part 3 - S
yst
em Design and Ins
talla
tion
Amazon Unitario Top Discharge
171
8 Charging Refrigerant
8.1 Calculating Additional Refrigerant Charge
The additional refrigerant charge required depends on the lengths and diameters of the outdoor and indoor liquid pipes.
Table 3-8.1 shows the additional refrigerant charge required per meter of equivalent pipe length for different diameters
of pipe. The total additional refrigerant charge is obtained by summing the additional charge requirements for each of the
outdoor and indoor liquid pipes, as in the following formula, where L
1
to L
8
represent the equivalent lengths of the pipes of
different diameters. Assume 0.5m for the equivalent pipe length of each branch joint.
Additional refrigerant charge R (kg) =
L
1
(
Φ6.35
) × 0.022
+
L
2
(
Φ9.53
) × 0.057
+
L
3
(
Φ12.7
) × 0.110
+
L
4
(
Φ15.9
) × 0.170
+
L
5
(
Φ19.1
) × 0.260
+
L
6
(
Φ22.2
) × 0.360
+
L
7
(
Φ25.4
) × 0.520
+
L
8
(
Φ28.6
) × 0.680
Table 3-8.1: Additional refrigerant charge
Liquid side
piping (mm)
Additional refrigerant charge per
meter of equivalent length of piping
(kg)
Φ6.35
0.022
Φ9.53
0.057
Φ12.7
0.110
Φ15.9
0.170
Φ19.1
0.260
Φ22.2
0.360
Φ25.4
0.520
Φ28.6
0.680
8.2 Adding Refrigerant
Notes for installers
Caution
Only charge refrigerant after performing a gastightness test and vacuum drying.
Never charge more refrigerant than required as doing so can lead to liquid hammering.
Only use refrigerant R410A - charging with an unsuitable substance may cause explosions or accidents.
Use tools and equipment designed for use with R410A to ensure required pressure resistance and to prevent
foreign materials from entering the system.
Refrigerant must be treated in accordance with applicable legislation.
Always use protective gloves and protect your eyes when charging refrigerant.
Open refrigerant containers slowly.
Procedure
The procedure for adding refrigerant is as follows:
Step 1
Calculate additional refrigerant charge R (kg) (see Part 3, 8.1 “Calculating Additional Refrigerant Charge”)
Step 2
Place a tank of R410A refrigerant on a weighing scale. Turn the tank upside down to ensure refrigerant is
charged in a liquid state. (R410A is a blend of two different chemicals compounds. Charging gaseous R410A
into the system could mean that the refrigerant charged is not of the correct composition).
After vacuum drying (see Part 3, 5.9 “Vacuum Drying”), the blue and red pressure gauge hoses should still be
connected to the pressure gauge and to the master unit stop valves.
Connect the yellow hose from the pressure gauge to the R410A refrigerant tank.
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Step 3
•
Open the valve where the yellow hose meets the pressure gauge, and open the refrigerant tank slightly to let the
refrigerant eliminate the air. Caution: open the tank slowly to avoid freezing your hand.
•
Set the weighing scale to zero.
Step 4
•
Open the three valves on the pressure gauge to begin charging refrigerant.
•
When the amount charged reaches R (kg), close the three valves. If the amount charged has not reached R (kg)
but no additional refrigerant can be charged, close the three valves on the pressure gauge, run the outdoor unit in
cooling mode, and then open the yellow and blue valves. Continue charging until the full R (kg) of refrigerant has
been charged, then close the yellow and blue valves. Note: Before running the system, be sure to complete all the
pre-commissioning checks as listed in Part 3, 11.3 “Pre-commissioning Checks” and be sure to open all stop valves
as running the system with the stop valves closed would damage the compressor.
Figure 3-8.1: Charging refrigerant
1
2
1
2
Pressure gauge
Pressure
gauge
Yellow hose
R410A
refrigerant tank
Weighing scale
Outdoor unit
Blue hose
Red hose
Stop valve
service port
Field piping
Gas pipe stop valve
Liquid pipe stop valve
