Carrier 38AUQ 16 Series, Installation, Start-Up And Service Instructions Manual

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11
Make Piping Connections —
Piping connections at the 38AUQ 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
π
-in SAE service
fittings with Schrader valve cores (see Fig. 7). 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
C10203
Fig. 7 -- Typical Piping Connection Assembly
When connecting the field tubing to the 38AUQ service
valves, wrap the valves in wet rags to prevent overheating
Pressure-test all joints from outdoor unit connections over
to the indoor 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 2-3 in-lbs
(23-34 N-cm).
Where vapor line is exposed to outdoor air, line must be
insulated. See Table 6 for insulation requirements.
Table 6 – Insulation for Vapor Line Exposed
to Outdoor Conditions
LENGTH OF EXPOSED
VAPOR LINE*
INSULATION THICKNESS
†
ft m in. mm
10 3
3
/
8
10
25 8
1
/
2
13
50 15
3
/
4
19
* Recommended vapor line insulation for piping exposed to outdoor
conditions to prevent loss of heating during heating cycle. When vapor
line goes through interior spaces, insulation should be selected to pre-
vent condensation on cooling cycle. Heating capacity should be re-
duced 1000 Btuh (295 W) if over 35 ft (11 m) of vapor line with
3
/
4
in. (19
mm) insulation is exposed to outdoor conditions.
† Closed cell foam insulation with a thermal conductivity of: 0.28 Btu
S
in./ft
2
S
h
S °
F (0.04 W/m
S °
C).
Evacuation/Dehydration —
Evacuate and dehydrate the connected refrigeration
system(s) (excluding the 38AUQ unit) to 500 microns
using a two-stage vacuum pump attached to the service
ports outside the 38AUQ 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 pressures than standard R--22 systems. Do not
use R--22 service equipment or components on Puron
refrigerant equipment.
!
WARNING
IMPORTANT
: Charge in Cooling mode only!
Preliminary Charge —
Before starting the unit, charge R-410A liquid refrigerant
into the high side of each 38AUQ circuit through the
liquid service valve(s). The amount of refrigerant added
must be at least 80% of the operating charge listed in
Table 2 for LINEAR line length LESS the factory charge
quantity (if factory shipping charge has not been
removed). See the following example.
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:
38AUQ*25
60-ft (18.3 m) linear line length
Equivalent line length 90-ft (27.4 m)
Cooling Liquid Lift: 20-ft (6.1 m)
Select line sizes from Table 2 (38AUQ):
Liquid
1
/
2
--in (provides liquid lift to 24--ft (7.3 m))
Vapor 1-
1
/
8
in.
Charge (each circuit):
1
/
2
--in liquid line: 30.7 lbs (at 75-ft linear length)
80% of Operating Charge:
0.80 x 30.7 = 24.6 lbs
Factory Shipping Charge: 9 lbs
Field-Charge (each circuit):
24.6 -- 9.0 = 15.6 lbs
For linear line lengths longer than 125 ft (38.1 m), contact
your local Carrier representative for system charge value.
38A
U
Q