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www.DaikinApplied.com 101
IOM 1206-7 • TRAILBLAZER
™
MODEL AGZ CHILLERS
Refrigerant Charging
CAUTION
When moving refrigerant to/from the chiller using an auxiliary
tank, a grounding strap must be used. An electrical charge
builds when halo-carbon refrigerant travels in a rubber
hose. A grounding strap must be used between the auxiliary
refrigerant tank and the end sheet of the chiller (earth ground),
which will safely take the charge to the ground. Damage to
sensitive electronic components could occur if this procedure
is not followed.
If a unit is low on refrigerant, you must first determine the
cause before attempting to recharge the unit. Locate and repair
any refrigerant leaks. Soap works well to show bubbles at
medium size leaks but electronic leak detectors are needed to
locate small leaks.
Charging or check valves should always be used on charging
hoses to limit refrigerant loss and prevent frostbite. Ball valve
type recommended. Charge to 80-85% of normal charge
before starting the compressors.
Charging procedure
The units are factory-charged with R-410A. Use the following
procedure if recharging in the field is necessary:
To prevent fractionalization, liquid must be charged from
the refrigerant cylinder, unless charging the entire cylinder
contents.
The charge can be added at any load condition between
25 to 100 percent load per circuit, but at least two fans per
refrigerant circuit should be operating if possible.
• Start the system and observe operation.
• Trim the charge to the recommended liquid line sub-
cooling (approximately 15-20°F typical).
• Verify the suction superheat (10 degrees F for EEVs and
10 – 12 degrees F for TXVs) at full load conditions.
• Use standard charging procedures (liquid only) to top off
the charge.
• Check the sight glass to be sure there is no refrigerant
flashing.
With outdoor temperatures above 60°F (15.6°C), all condenser
fans should be operating and the liquid line temperature
should be within 5°F to 10°F (2.8°C to 5.6°C) of the outdoor
air temperature. At 25-50% load, the liquid line temperature
should be within 5°F (2.8°C) of outdoor air temperature with all
fans on. At 75-100% load the liquid line temperature should be
within 10°F (5.6°C) of outdoor air temperature with all fans on.
If the unit is at steady full load operation and bubbles are
visible in the sight glass, then check liquid subcooling. The
AGZ units have a condenser coil design with approximately
15% of the coil tubes located in a subcooler section of the coil
to achieve liquid cooling to within 5-10°F (2.8-5.6°C) of the
outdoor air temperature when all condenser fans are operating.
Subcooling should be checked at full load with 70°F (21.1°C)
ambient temperature or higher, stable conditions, and all fans
running. Liquid line subcooling at the liquid shut-off valve
should be between 15 and 20 degrees F at full load.
If subcooling is low, add charge to clear the sight glass. Once
the subcooler is filled, extra charge will not lower the liquid
temperature and does not help system capacity or efficiency.
If subcooling is normal (15 to 20 degrees F at full load) and
flashing is visible in the sight glass, check the pressure drop
across the filter-drier. See
page 97
for maximum allowable
pressure drops.
It may be necessary to add refrigerant through the compressor
suction. Because the refrigerant leaving the cylinder must be
a liquid, exercise care to avoid damage to the compressor by
using a flow restrictor. A sight glass can be connected between
the charging hose and the compressor. It can be adjusted to
have liquid leave the cylinder and vapor enter the compressor.
Overcharging of refrigerant will raise the compressor discharge
pressure due to filling of the condenser tubes with excess
refrigerant.
Service
With R-410A, fractionalization, if due to leaks and recharge has
a minimal effect on performance or operation.
Special tools will be required due to higher refrigerant
pressures with R-410A. Oil-less/hp recovery units, hp recovery
cylinders (DOT approved w/525# relief), gauge manifold 30”-
250 psi low/0-800 psi high, hoses w/800 psi working & 4,000
psi burst.
All filter driers and replacement components must be rated
POE oils and for the refrigerant pressure (R-410A 600psig
typical).
R-410A compressor internal relief is 600-650 psid.
Brazed connections only. No StayBrite or solder connections
(solder should never be used with any refrigerant). K or L type
refrigeration tubing only. Use nitrogen purge. Higher R-410A
pressures and smaller molecule size make workmanship more
critical.
R-410A must be charged from cylinder as a liquid unless entire
cylinder is used. Use a Refrigerant flow restrictor if charging
liquid to suction or to a system at pressure below a saturated
temperature of 32° F.
EPA recovery and handling requirements for R-410A are the
same as R-22.
Cooling the recovery cylinder will speed recovery and lessen
stress on recovery equipment.
WARNING
Service on this equipment is to be performed by qualified
refrigeration personnel familiar with equipment operation,
maintenance, correct servicing procedures, and the safety
hazards inherent in this work. Causes for repeated tripping
of equipment protection controls must be investigated and
corrected. Disconnect all power before doing any service
inside the unit. Servicing this equipment must comply with the
requirements set forth by the EPA in regards to refrigerant
reclamation and venting.
Summary of Contents for AGZ030E
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