Flow Detection - Carrier 19XRV Start-Up, Operation And Maintenance Instructions Manual

L,_ 3 00in ............ _-J CONNECTOR
_-_-_ _---- _i6,35" mm)(762 mm) , .- RECEPTACLE
NPT WATERPROOF SEAL
Fig. 11 -- Control Sensors (Temperature)
3.6" TUBE LENGTH
(90MM)
\EATSHR,NK\
2-CONDUCTOR CABLE
Fig. 12 -- Temperature Sensor Used
With Thermal Well
1/4" SAE FEMALE FLARE WITH
INTEGRAL SCHRADER DEFLATOR
Fig. 13 -- Control Sensors
(Pressure Transducers, Typical)
A Refrigerant Saturation Temperature sensor (thermistor) is
located in the base of the evaporator, sensing refrigerant
temperature directly. Evaporator and condenser water side
differential pressure transducers _u'e not stan&trd and are not
required. The [CVC software uses the evaporator saturation
refrigerant temperature in place of diffferential pressure flow
detection to provide evaporator fieeze protection.
Approach temperatures are shown in the HEAT_EX scleen.
EVAPORATOR APPROACH is defined as LEAVING
CHILLED WATER temperature minus EVAP SATURATION
TEMP (from the temperature sensor). CONDENSER AP-
PROACH is defined as CONDENSER REFRIG TEMP
(derived from condenser pressure) minus LEAVING CON-
DENSER WATER temperature. When the chiller is running,
the displayed v_due for either approach will not be less than
0.2 ° F (0.1 o C). If either approach value exceeds the value con-
figured in the SETUPI screen, the corresponding Approach
Alert message will be entered into the Alert Histo U table.
FLOW DETECTION- Flow detection for the evaporator
and condenser is a required condition for stm-t-up and used in
the freeze protection safety. Flow and no flow conditions are
detected from a combination of several measurements. The
usage of waterside diffelential pressme measmements is not
standard or required.
Positive detemrination of flow on the evaporator side is
made if the following conditions ale true: (1) the EVAP SATU-
RATION TEMP reads higher than 1° F (0.6 ° C) above the
EVAP REFRIG TRIPPOINT. and (2) EVAP REFRIG TEMP
(determined from the Evaporator Pressure sensor) is greater
than the EVAP REFRIG TRIPPOINT. (If the unit is in Pump-
down or Lockout mode, conditions (1) and (2) ;ue not required
to establish flow.) On the condenser side, positive detemrina-
tion of flow is made if the following conditions are tree: (1) the
CONDENSER PRESSURE is less than 165 psig (1139 kPa),
and (2) CONDENSER PRESSURE is less than the configured
COND PRESS OVERRIDE threshold by more than 5 psi
(34.5 kPa). In addition, if the waterside differentkd pressure
measurement option is enabled, the watel_ide pressure differ-
entials (cooler and condenser) must exceed their respective
configured cutout thresholds.
A No Flow determination is made on the evaporator side if
(1) the EVAP SATURATION TEMP reads lower than 1° F
(0.6 ° C) below the EVAP REFRIG TRIPPOINT. or (2) EVAP
REFRIG TEMP (determined from the Evaporator Pressure
sensor) is less than the EVAP REFRIG TRIPPOINT and the
EVAPORATOR APPROACH exceeds the configured EVAP
APPROACH ALERT threshold. On the condenser side, a
No Flow determination is also made if the CONDENSER
APPROACH exceeds the configured COND APPROACH
ALERT threshold and either (1) CONDENSER PRESSURE
exceeds 165 psig (1139 kPa) or (2) CONDENSER PRES-
SURE exceeds the configured COND PRESS OVERRIDE
threshold by more than 5 psi (34.5 kPa). In addition, if the wa-
ter side differential pressure measurement option is enabled, a
differential below the configured EVAP or COND FLOW
DELTA P CUTOUT v_due is sufficient to establish No Flow in
either heat exchangel:
If No Flow (for either cooler or condenser) has been deter-
mined, and subsequently conditions change such that neither
conditions for Flow nor No Flow are _dl satisfied, the determi-
nation will remain No Flow.
In the standard [CVC setup, waterside differential pressure
indication is disabled by default. The displays for CHILLED
WATER DELTA P and CONDENSER WATER DELTA P in
the HEAT_EX screen will show "*****". In order to enable
the option and display a value, change FLOW DELTA P
DISPLAY to ENABLE in the SETUPI scleen. Pairs of pres-
sure transducers may be connected to the CCM at temrinals
J3 13-24 in place of the standard resistors and jumpers to deter-
mine water-side pressme differentials as in the standard ICVC
configuration. (NOTE: If the FLOW DELTA P DISPLAY is
enabled but the standard CCM connection is retained, a differ-
ential value of approximately 28.5 psi (197 kPa) will _flways be
displayed.)
If watel_ide diffelential plessure transducel_ me used, flow
is detected fi_m differential pressure between sensors (pressure
transducers) located in water inlet and outlet nozzles, for earl1
heat exchangeE The thresholds for flow determination (EVAP
FLOW DELTA P CUTOUT. COND FLOW DELTA P CUT-
OUT) are configured in the SETUPI screen. If the measured
differential is less than the corresponding cutout value for 5
seconds, the determination is that flow is absent. If no flow is
detected after W_TER FLOW VERIFY TIME (configured in
the SETUPI screen) after the pump is commanded to start by
the PIC, a shutdown will result, and the corresponding loss-of-
flow _dmm (alarm state 229 or 230) will be declared. If the
measured differenti_d exceeds the Flow Delta P cutout value,
flow is considered to be present.
Alternatively. norm_dly open flow switches may be used for
flow indication. In this case, inst_dl an evaporator side flow
switch in parallel with a 4.3k ohm resistor between CCM
terminals J3 17-18, replacing the jumpel: See page 114. For a
condenser side flow switch do the same between CCM termi-
nals J3 23-24. If this type of flow switch circuit is used, it is
important to perform a zero point calibration (with the flow
switch open).
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