Carrier Gemini 38AU07 Series Installation 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 circuit 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 cir-
cuits is connected to a 38AUD, the lower coil circuit should
be connected to the 38AUD unit's Circuit 1 so that the evapo-
rator'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 assembled to avoid piping errors.
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 suction 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 ar-
rangement of the 40RU changes. In a vertical arrangement,
the 40RU unit's lower coil segment is segment 2; this seg-
ment 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
Circuit 1
Connections
Circuit 2
Connections
40RU COIL CONNECT TO
SEGMENT 38AUD
2 Circuit 1
1 Circuit 2
1 Circuit 1
2 Circuit 2
VERTICAL INSTALLATION
HORIZONTAL INSTALLATION
Fig. 8 — Typical Evaporator Coil Connections
INSTALL FILTER DRIER(S) AND MOISTURE INDICA-
TOR(S)
Every unit MUST have a filter drier in the liquid line.
38AUD models require two filter driers (one in each liquid
line). Locate the filter drier(s) at the indoor unit, close to the
evaporator coil's thermal expansion valve (TXV) inlets.
The 38AU units include one (38AUZ) or two (38AUD)
Puron-duty filter drier(s), shipped in cartons attached to the
unit basepan (see Table 11). 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.
Table 11 — Puron-duty Filter Drier(s)
MODEL LIQUID LINE
QTY
SIZE
38AUZ*07 1
38AUZ*07 1
38AUZ*07 1
38AUZ*07 1
38AUD*12 2
38AUD*14 2
Installation of liquid line moisture indicating sightglass in
each circuit is recommended. Locate the sightglass(es) between
the outlet of the filter drier and the TXV inlet.
Refer to Table 12 for recommendations on refrigeration
specialties.
In some applications, depending on space and conve-
nience requirements, it may be desirable to install 2 filter dri-
ers and sight glasses in a single circuit application. One filter
drier and sight glass may be installed at A locations (see Fig.
9) or 2 filter driers and sight glasses may be installed at B lo-
cations (see Fig. 9 and 10).
11
LIQUID LINE
CONNECTION
SUCTION-VAPOR
CONNECTION
CONDENSATE DRAIN
CONNECTION
FIRST ON/LAST OFF = 2
CONDENSATE DRAIN CONNECTION
FIRST ON/LAST OFF = 1
(40RU)
DESICCANT
OD (in.) VOLUME
3 / 8 cu in.
8
1 / 16 cu in.
2
/ 16 cu in.
1
2
/ 16 cu in.
5
8
3 / 8 cu in.
8
1 / 16 cu in.
2
PART
NUMBER
REF.
KH43LG091
KH43LG085
KH43LG085
KH43LG086
KH43LG091
KH43LG085