14
Make Piping Connections —
Piping connections at the 38AUD unit are ball valves with
stub tube extensions. Do not open the unit service valves
until all interconnecting tube brazing as been completed.
The stub tube connections include
1
/
4
-in SAE service
fittings with Schrader valve cores (see Fig. 9). Before
making any brazed connections to the unit service valves,
remove both Schrader valve caps and cores and save for
re-installation. Connect a source for nitrogen to one of
these service fittings during tube brazing to prevent the
formation of copper oxides inside the tubes at brazed
joints.
Factory
High-Flow
Access Port
Service Valve
with Stem Cap
Field Service
Access Port
(Schrader core)
Sweat
Connection
C10073
Fig. 9 -- Typical Piping Connection Assembly
When connecting the field tubing to the 38AUD service
valves, wrap the valves in wet rags to prevent overheating
Pressure-test all joints from outdoor unit connections over
to the evaporator coil, using nitrogen as pressure and with
soap-and-bubbles.
When pressure-testing is completed, remove the nitrogen
source at the outdoor unit service valves and re-install the
two Schrader valve cores. Torque the cores to 23-34 N-cm
(2-3 in-lbs).
Evacuation/Dehydration —
Evacuate and dehydrate the connected refrigeration
systems (excluding the 38AUD unit) to 500 microns using
a two-stage vacuum pump attached to the service ports
outside the 38AUD service valves, following description
in GTAC II, Module 4, System Dehydration.
UNIT OPERATION AND SAFETY HAZARD
Failure to follow this warning could cause personal
injury, death and/or equipment damage.
Puron
R
(R--410A) refrigerant systems operate at
higher pressure than standard R--22 systems. Do not
use R--22 service equipment or components on Puron
refrigerant equipment.
!
WARNING
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 cylinders. 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 position (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 recommended that refrigerant always be removed
from the cylinder as a liquid. Admit liquid refrigerant into
the system in the discharge line. If adding refrigerant into
the suction line, use a commercial metering/expansion
device at the gauge manifold; remove liquid from the
cylinder, pass it through the metering device at the gauge
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.
Preliminary Charge —
Before starting the unit, charge R-410A liquid refrigerant
into the high side of each 38AUD circuit through the
liquid service valve(s). The amount of refrigerant added
must be at least 80% of the operating charge listed in
Table 4 for LINEAR line length LESS the factory charge
quantity (if factory shipping charge has not been
removed). See example below.
Allow high and low side pressures to equalize. If pressures
do not equalize readily, charge R-410A vapor (using
special service manifold with expansion device) into the
suction line service port for the low side of system to
assure charge in the evaporator. Refer to GTAC II,
Module
5,
Charging,
Recover,
Recycling,
and
Reclamation for liquid charging procedures.
Example:
38AUD*16 (Novation)
20 m linear line length
Equivalent line length 30 m
Liquid Lift: 10 m
(linear measure, indoor unit above outdoor unit)
Select line sizes from Table 4 (38AUD):
Liquid
3
/
8
in
Suction 1-
1
/
8
in.
Operating Charge
Each circuit: 7.0 kg (at 23 m linear length)
80% of Operating Charge:
Each circuit: 0.80 x 7.0 = 5.6 kg
Factory Shipping Charge: 2.7 kg Field-charge quantity:
5.6 kg – 2.7 kg = 2.9 kg
For linear line lengths longer than 38 m (125 ft), contact
your local Carrier representative for system charge value.
38A
U
D
Summary of Contents for 38AUD 16 Series
Page 21: ...21 CIRCUIT 1 CIRCUIT 2 C10946 Fig 16 38AUD 16 Charging Chart Novation 38AUD...
Page 22: ...22 C10949 Fig 17 38AUD 16 Charging Chart RTPF 38AUD...
Page 23: ...23 CIRCUIT 1 CIRCUIT 2 C10950 Fig 18 38AUD 25 Charging Chart RTPF 38AUD...
Page 24: ...24 C10084A Fig 19 Typical 38AUD 16 Wiring Diagram 38AUD...
Page 25: ...25 C10085A Fig 20 Typical 38AUD 25 Wiring Diagram 38AUD...