OPERATING DATA
Sensors —
The electronic control uses 4 to 10 ther-
mistors to sense temperatures for controlling chiller opera-
tion. See Table 2. These sensors are outlined below. See
Fig.7-10forthermistor locations. Thermistors T1-T9 are
5kVat 25 C (77 F) and are identical in temperature versus
resistance and voltage drop performance. Thermistor T10 is
a10kVat 25 C (77 F) and has a different temperature vs
resistance and voltage drop performance. See Thermistors
section on page 55 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. The sensor well is
located directly in the refrigerant path.
T2 — COOLER ENTERING FLUID SENSOR — This ther-
mistor 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 out-
side of a return bend of the condenser coils.
T5, T6 — COOLER SUCTION TEMPERATURE SEN-
SORS — These thermistors are located next to the refrig-
erant 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
refrigerant has passed over the motor and is about to enter
the cylinders. 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 — Sen-
sor T9 is an accessory sensor that is remotely mounted and
used for outdoor-air temperature reset.
LEGEND
EXV — Electronic Expansion Valve
*And associated modular units.
Fig. 7 — Cooler Thermistor Locations
040-110*
130-210*
11
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