Carrier Gemini 38AU Series Installation, Start-Up And Service Instructions Manual page 11

38AUD PIPING CONNECTIONS
The 38AUD unit's two circuits are designated Circuit 1 and
Circuit 2. Circuit 1 is controlled by the thermostat's Y1 (or TC1)
contact and will be the first circuit on and last circuit off. Circuit 2
is controlled by the thermostat's Y2 (or TC2) contact and this cir-
cuit is always the "lag" circuit.
See Fig. 7 for location of Circuit 1 and Circuit 2 service valves and
field piping connections. Circuit 1 is on the right-hand side of the
service valve compartment; Circuit 2 is on the left.
When a single piece evaporator coil with two separate circuits is
connected to a 38AUD, the lower coil circuit should be connected
to the 38AUD unit's Circuit 1 so that the evaporator's lower coil
segment is first-on/last-off (to avoid re-evaporation of condensate
on dry lower coil segments).
CKT
2
CKT
1
Fig. 7 — 38AUD Service Valve Locations
Plan the Circuit 1 and Circuit 2 tubing segments carefully, mark
each segment and check constantly as piping systems are assem-
bled to avoid piping errors.
The 38AUD unit cannot be field-piped as a single-circuit/tandem
system.
FINAL TUBING CHECK. 38AUD
Before completing the field piping connections to the 38AUD
unit service valves, confirm that the suction line to the indoor
coil's first-on/last-off circuit (and its companion liquid line) are
correctly identified as Circuit 1 use for the 38AUD unit. If a suc-
tion riser is required, it must be in Circuit 1.
Connecting 40RU to 38AUD
The 40RU fan coil in sizes 12, 14 and 16 is a face-split coil design
that also has its circuits designated as 1 and 2. See Fig. 8. Note that
the lower coil segment changes as the arrangement of the 40RU
changes. In a vertical arrangement, the 40RU unit's lower coil seg-
ment is segment 2; this segment should be connected to the
38AUD unit's Circuit 1. In a horizontal arrangement, the 40RU
unit's lower segment is now segment 1; this segment should be
connected to the 38AUD unit's Circuit 1.
Note that refrigerant suction piping should be insulated.
40RU COOLING
ARRANGEMENT STAGE
Y1
Vertical
Y2
Y1
Horizontal
Y2
INSTALL FILTER DRIER(S) AND MOISTURE
INDICATOR(S)
Every unit MUST have a filter drier in the liquid line. 38AUD
models require two filter driers (one in each liquid line). Locate
CIRCUIT 1
CONNECTIONS
CIRCUIT 2
CONNECTIONS
40RU COIL CONNECT TO
SEGMENT 38AUD
2 Circuit 1
1 Circuit 2
1 Circuit 1
2 Circuit 2
the filter drier(s) at the indoor unit, close to the evaporator coil's
thermal expansion valve (TXV) inlets.
VERTICAL INSTALLATION
FIRST ON/LAST OFF = 1
HORIZONTAL INSTALLATION
Fig. 8 — Typical Evaporator Coil Connections (40RU)
The 38AU units include one (38AUZ) or two (38AUD) Puron-
duty filter drier(s), shipped in cartons attached to the unit basepan
(see Table 12). Remove the filter drier(s) and prepare to install in
the liquid line(s) at the evaporator coil. Do not remove connection
fitting plugs until ready to connect and braze the filter drier into
the liquid line position.
Installation of liquid line moisture indicating sightglass in each
circuit is recommended. Locate the sightglass(es) between the out-
let of the filter drier and the TXV inlet.
Refer to Table 13 for recommendations on refrigeration
specialties.
Table 12 — Puron-duty Filter Drier(s)
LIQUID LINE
MODEL SIZE QTY
38AUZ*07 1
38AUZ*08 1
38AUZ*12 1
38AUZ*14 1
38AUD*12 2
38AUD*14 2
Table 13 — Refrigerant Specialties Part Numbers
LIQUID LINE
LIQUID
SOLENOID
LINE
VALVE
SIZE
(LLSV)
/ EF680033
3
8
1 / EF680035
2
5 / EF680028
8
In some applications, depending on space and convenience re-
quirements, it may be desirable to install 2 filter driers and sight
11
LIQUID LINE
CONNECTION
SUCTION-VAPOR
CONNECTION
CONDENSATE DRAIN
CONNECTION
FIRST ON/LAST OFF = 2
CONDENSATE DRAIN CONNECTION
DESICCANT
OD (in.) VOLUME
3 / 8 cu in.
8
/ 16 cu in.
1
2
/ 16 cu in.
1
2
5 / 16 cu in.
8
3 / 8 cu in.
8
1 / 16 cu in.
2
SIGHT
LLSV COIL
GLASS
EF680037 KM680008
Provided with
EF680037 KM680004
EF680032 KM680005
PART
NUMBER
REF.
KH43LS091
KH43LS085
KH43LS085
KH43LS086
KH43LS091
KH43LS085
FILTER
DRIER
unit, see
Table 12