Section 6 - Commissioning; Preparation - Power Off - York YLAA Series Installation Operation & Maintenance

FORM 150.72-ICOM6
ISSUE DATE: 12/29/2017
Commissioning of this unit should only
be carried out by Johnson Controls Au-
thorized personnel.
Commissioning personnel should be thoroughly famil-
iar with the information contained in this literature, in
addition to this section.
Perform the commissioning using the detailed checks
outlined. See Equipment Pre-Startup And Startup
Checklist (Form 150.72-CL1) as the commissioning
procedure is carried out.
PREPARATION – POWER OFF
The following basic checks should be made with the
customer power to the unit switched OFF.
Inspection
Inspect unit for installation damage. If found, take ac-
tion and/or repair as appropriate.
Refrigerant Charge
Packaged units are normally shipped as standard with
a full refrigerant operating charge. Check that refrig-
erant pressure is present in both systems and that no
leaks are apparent. If no pressure is present, a leak test
must be undertaken, the leak(s) located and repaired.
Remote systems and units are supplied with a nitrogen
holding charge. These systems must be evacuated with
a suitable vacuum pump/recovery unit as appropriate
to below 500 microns.
Do not liquid charge with static water in the cooler.
Care must also be taken to liquid charge slowly to
avoid excessive thermal stress at the charging point.
Once the vacuum is broken, charge into the condenser
coils with the full operating charge as given in SEC-
TION 5 – TECHNICAL DATA.
ALWAYS keep the water pump running
when vacuuming the system, removing
refrigerating from the system or adding
refrigerant to the system until the process
is completed. If you do NOT, the evapora-
tor may freeze and ruin the system.
JOHNSON CONTROLS
SECTION 6 – COMMISSIONING
Charging Refrigerant
If you vacuum the system first, add only the volume of
refrigerant shown on the nameplate.
However, sometimes the system can run without
enough refrigerant in it. If you have no idea how much
refrigerant is inside of the system, then follow the steps
below.
Charging after vacuuming - NEVER add
more than 5% of specified amount into the
evaporator. This will lead to compressor
failure when compressor starts. It may
also shorten the life of the compressor
if too much refrigerant stays inside the
evaporator.
Do NOT overcharge the system. Otherwise
High Discharge Pressure will frequently
occur.
1. Connect the charging hose between the refrigerant
tank and the angle valve at the inlet of evaporator.
Exclude the air inside of hose.
2. Put the refrigerant tank on a scale and read the ini-
tial weight. Leave the tank on scale until process
is complete.
3. Get as many compressors running as the system
permits.
4. Open the angle valve 1.5 turns.
5. Open the valve on the tank.
Quickly shut down the angle valve or
the tank valve immediately if all of com-
pressors stop suddenly in the process of
charging.
6. Monitor the suction superheat (SH) and liquid
subcooling (SC). If SH is around 10R and SC>6R,
close the angle valve. Wait at least 15 min;
7. If SC<10R or SH>10R always, continue to charge
the system. Open the angle valve 1.5 turns. Close
it after one pound is added. Wait another 15min.
Repeat this step until both SC and SH are around
10R with all of the fans and compressors running;
8. Close the angle valve and tank valve. Disconnect
the hose.
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