Carrier 09FC020, Инструкции по установке, запуску и обслуживанию

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linkage to verify the “bypass valve” arm will not move any
further in the CW direction.
6. Add cotter pins to the clevis pin and tighten the adjuster nut.
7. Remove handle from actuator and return to storage position.
Valve will not operate with handle in place. Make sure to
replace the waterproof cap.
Fig. 42 — Bypass Mode
Fig. 43 — Free Cooling
Thermistor
Electronic control uses (3) 5 k  thermistors to sense temperatures
used to control operation of the chiller. Thermistors for Entering
Water Temperature (EWT), and Leaving Water Temperature
(LWT) and Outdoor Air Temperature (OAT) are identical in their
temperature and voltage drop performance.
Resistance at various temperatures are listed in Table 18. For dual
chiller operation, a dual chiller sensor is required which is a 5 k

thermistor.
External Control Valve
Fan speed is used for leaving water temp control. In extreme con -
ditions, the leaving water setpoint may be met with the fans at
0 Hz. In this condition the leaving water temperature may contin -
ue to drop until an alarm is tripped. The unit will return to bypass
mode in the alarm condition. Once the water temp increases from
the building load, the alarm will reset and the unit will go back
into free cooling mode.
If more precise water temp control is desired, an external control
valve may be added to bypass the water around the free cooling
unit. This can be controlled by the unit controller. The controller
will provide a 0 to 10V signal to the valve through terminal TB1-5
and 6.
Replacing Thermistors (EWT, LWT)
Add a small amount of thermal conductive grease to the thermis -
tor well and end of probe. For all probes, tighten the retaining nut
1/4 turn past finger tight. See Fig. 44. Insulate the thermistor with
cork tape or other appropriate insulating material.
Fig. 44 — Thermistor Well (EWT, LWT) Thermistor
Mounting
Replacing Thermistor (OAT)
The OAT thermistor is does not use a thermowell, the OAT should
be in a location that is not affected by sunlight, providing an accu -
rate outdoor air temperature. It should hang about 3 in. below the
condenser section nearest the control panel.
Thermistor/Temperature Sensor Check
A high quality digital volt-ohmmeter is required to perform this
check.
1. Connect the digital voltmeter across the appropriate thermis -
tor terminals at the J3 terminal strip on the controller. See
Fig. 45.
2. Using the voltage reading obtained, read the sensor tempera -
ture from Table 18. Supply voltage to the thermistor should
be 4 vdc ± 0.2 v with the thermistor disconnected from the
controller.
3. To check thermistor accuracy, measure temperature at probe
location with an accurate thermocouple-type temperature
measuring instrument. Insulate thermocouple to avoid ambi -
ent temperatures from influencing reading. Temperature mea -
sured by thermocouple and temperature determined from
thermistor voltage reading should be close, ± 5°F (3°C) if
care was taken in applying thermocouple and taking readings.
Fig. 45 — Thermistor Connections to Controller, J3
Valve Stem
Position – Bypass
Valve
Actuator at “0”
Full Clockwise
Rotation
Bypass Valve Open
(Entering Water
Connection)
Bypass Valve Closed
(Entering Water Connection)
Actuator at “90”
Full CCW Rotation