19
Step 4 — Pressure and Vacuum Test
System
—
After completing the refrigerant piping, perform
the following pressure test:
1.
Connect nitrogen canister to the system through the high-
pressure gas side valve from the meter connector.
2.
Apply nitrogen pressure gradually to 540 psig.
3.
If rapid pressure decrease is apparent; locate and repair
the leak, and pressurize the system again.
4.
Repeat Steps 1-3 until the system remains at 540 psig for
24 hours.
After completing the pressure test, perform the following
vacuum test:
1.
Relieve the system of the nitrogen gas.
2.
Connect a vacuum pump capable of achieving 500
microns or lower absolute pressure.
3.
Vacuum the system to 500 microns or lower, and check
for rapid pressure change.
4.
Repeat Steps 1-3 until the system remains at 500 microns
or lower for an hour.
When finished, replace the vacuum pump with the R-410A
refrigeration canister.
Step 5 — Adjust Refrigerant Charge
—
Calculate
the amount of refrigerant to add using Table 17 and Fig. 26.
The refrigerant is R-410A.
NOTE: Assume equivalent pipe length of the branch joint to
be 1.6 ft (for calculation purposes).
Table 17 — Refrigerant to Add Using Liquid Pipe
Size
Fig. 26 —Calculating Amount of Refrigerant to Add
All service valves on the outdoor units should remain fully
closed.
R-410A refrigerant should be added (in liquid state) at the
liquid line service port on the header unit.
If the total calculated amount of refrigerant can be added to
the system, the charging process is finished.
If the total calculated amount of refrigerant cannot be added
to the system, close the valve on the refrigerant bottle, move
the charging house from the liquid line service port to the
suction line service port.
Open the suction and liquid service valves on the header
unit and start the system in cooling mode.
Slowly open the valve on the refrigerant bottle and carefully
release liquid refrigerant into the suction service port.
If the total calculated charge amount is added completely to
the system, the charging process is finished.
Step 6 — Complete Electrical Connections
POWER SUPPLY — Electrical
characteristics
of
the
available power supply must agree with the unit nameplate
rating. Circuit breaker size and supply voltage must be as
shown in Table 18.
PIPE SIZE ON LIQUID SIDE (in.)
REFRIGERANT TO BE
ADDED PER FOOT (lb/ft)
1
/
4
0.015
3
/
8
0.040
1
/
2
0.080
5
/
8
0.120
3
/
4
0.181
7
/
8
0.255
WARNING
Electrical shock can cause personal injury and death. Dis-
connect the power supply before making wiring
connections. There may be more than one disconnect
switch. Tag all disconnect locations to alert others not to
restore power until work is completed.
WARNING
All units must be wired strictly in accordance with the
wiring diagram furnished with the unit. Any wiring
different from the wiring diagram could result in personal
injury and property damage.
CAUTION
Any original factory wiring that requires replacement must
be replaced with wiring material having a temperature
rating of at least 105
C.
Ensure supply voltage to the unit, as indicated on the serial
plate, is not more than 10% over the rated voltage or 10%
under the rated voltage.
Failure to follow these recommendations may result in
equipment damage.
WARNING
Operating unit on improper supply voltage or with
excessive phase imbalance may result in equipment
damage and can affect the manufacturer’s warranty.