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CLAMP
TXV SENSING
BULB
SENSING BULB INSULATION REMOVED FOR CLARITY
Fig. 20 — TXV Valve and Sensing Bulb
THERMAL EXPANSION
(TXV) VALVE
12
PURON (R-410A) REFRIGERANT
This unit is designed for use with Puron (R-410A) refrigerant. Do
not use any other refrigerant in this system.
Puron (R-410A) refrigerant is provided in pink (rose) colored cyl-
inders. These cylinders are available with and without dip tubes;
cylinders with dip tubes will have a label indicating this feature.
For a cylinder with a dip tube, place the cylinder in the upright po-
sition (access valve at the top) when removing liquid refrigerant
for charging. For a cylinder without a dip tube, invert the cylinder
(access valve on the bottom) when removing liquid refrigerant.
Because Puron (R-410A) refrigerant is a blend, it is strongly rec-
ommended that refrigerant always be removed from the cylinder
as a liquid. Add liquid refrigerant into the system in the discharge
line. If adding refrigerant into the suction line, use a commercial
metering/expansion device at the gage manifold; remove liquid
from the cylinder, pass it through the metering device at the gage
set and then pass it into the suction line as a vapor. Do not remove
Puron (R-410A) refrigerant from the cylinder as a vapor.
Refrigerant Charge
The amount of refrigerant charge is listed on the unit's name-
plate. Refer to Carrier Publication, "GTAC2-5 Charging, Recov-
ery, Recycling and Reclamation Training Manual" and the fol-
lowing procedures.
Unit panels must be in place when unit is operating during the
charging procedure. If unit is equipped with a head pressure con-
trol device, bypass it to ensure full fan operation during charging.
NOTE: Charge checking and adjustments must be made while the
system is operating in Cooling only.
NO CHARGE
Use standard evacuation techniques for Puron (R-410A) refrig-
erant. After evacuating system, weigh the specified amount of
refrigerant.
LOW-CHARGE COOLING
Using Cooling Charging Charts (Fig. 21-24), vary refrigerant until
the conditions of the appropriate chart are met. Note the charging
charts are different from type normally used. Charts are based on
charging the units to the correct superheat for the various operat-
ing conditions. An accurate pressure gage and temperature sensing
device are required. Connect the pressure gage to the service port
on the suction line. Mount the temperature sensing device on the
suction line and insulate it so that outdoor ambient temperature
does not affect the reading. Indoor-air cfm must be within the nor-
mal operating range of the unit.
How To Use Cooling Charging Charts
Take the outdoor ambient temperature and read the suction pres-
sure gage. Refer to chart to determine what suction temperature
should be. If suction temperature is high, add refrigerant. If suc-
tion temperature is low, carefully recover some of the charge. Re-
check the suction pressure as charge is adjusted.
EXAMPLE:
Model 50TCQ*D17
Outdoor Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . 85°F (29°C)
Suction Pressure . . . . . . . . . . . . . . . . . . . . . . . . .140 psig (965 kPa)
Suction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . 55°F (13°C)
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