11
OPERATING DATA
Sensors —
The electronic control uses 4 to 10 thermistors
to sense temperatures for controlling chiller operation. See
Table 2. These sensors are outlined below. See Fig. 7-10 for
thermistor locations. Thermistors T1-T9 are 5 kΩ at 77 F
(25 C). Thermistors T1, T2, T3-T6 and T7-T9 have different
temperature versus resistance and voltage drop performance.
Thermistor T10 is 10 kΩ at 77 F (25 C) and has a different tem-
perature vs resistance and voltage drop performance. See Ther-
mistors section on page 59 for temperature-resistance-voltage
drop characteristics.
T1 — COOLER LEAVING FLUID SENSOR — This ther-
mistor is located in the leaving fluid nozzle. The thermistor
probe is inserted into a friction-fit well.
T2 — COOLER ENTERING FLUID SENSOR — This
thermistor is located in the cooler shell in the first baffle space
in close proximity to the cooler tube bundle.
T3, T4 — SATURATED CONDENSING TEMPERATURE
SENSORS — These 2 thermistors are clamped to the outside
of a return bend of the condenser coils.
T5, T6 — COOLER SUCTION TEMPERATURE SEN-
SORS — These thermistors are located next to the refrigerant
inlet in the cooler head, and are inserted into a friction-fit well.
The sensor well is located directly in the refrigerant path. These
thermistors are not used on units with TXVs.
T7, T8 — COMPRESSOR SUCTION GAS TEMPERA-
TURE SENSORS — These thermistors are located in the lead
compressor in each circuit in a suction passage after the refrig-
erant has passed over the motor and is about to enter the cylin-
ders. These thermistors are inserted into friction-fit wells. The
sensor wells are located directly in the refrigerant path. These
thermistors are not used on units with TXVs.
T9 — OUTDOOR-AIR TEMPERATURE SENSOR —
Sensor T9 is an accessory sensor that is remotely mounted and
used for outdoor-air temperature reset.
MIN. 6” OF 22 AWG WIRES
WITH ENDS STRIPPED BACK
.25” ±1/8”
1/2” PVC SHIELD
1/2 NPT MALE
THREADED ADAPTER
3/16” DIA.
THERMOWELL (S.S.)
REF.
.83 D
(21.1)
REF.
1.81
(46.0)
REF.
5.75
(146.1
LEGEND
*And associated modular units.
AWG —
American Wire Gage
EXV —
Electronic Wire Gage
Fig. 7 — Cooler Thermistor Locations and Accessory Outdoor-Air Temperature Sensor Detail
040-110*
130-210*
