71
EVAPORATOR FREEZE PROTECTION
All evaporators are equipped with evaporator heaters (unless re-
moved as an option for Middle Eastern regions). The control
logic uses the unit status, OAT, and SST for all circuits to decide
if the evaporator heater should be energized. The evaporator
heaters can only be energized when the state of the unit is OFF.
The evaporator heaters will be energized according to the fol-
lowing logic:
1. The Evaporator Heater Setpoint is the Brine Freeze Setpoint
+ Evaporator Heater Delta Setpoint.
2. If the OAT is below the Evaporator Heater Setpoint or if the
SST of any one circuit is lower than the Evaporator Heater
Setpoint + 6°F (3.3°C), the evaporator heater is activated, or
if already activated, will remain on.
3. If the SST of all circuits is higher than the Evaporator Heater
Setpoint + 10°F (5.5°C), and if OAT is higher than the Evap-
orator Heater Setpoint +2°F, the evaporator heater will be
turned off, or if already off, will remain off.
4. If either condition 2 or condition 3 above is not met, the heat-
er mode remains unchanged.
If the entering or leaving water temperature is less than the
Brine Freeze Setpoint (Main Menu
Configuration Menu
Service Parameters
Brine Freeze Setpoint) +1.0°F
(0.5°C), then the heater will be turned on along with the pump.
A current sensing relay monitors the current to the evaporator
heaters. If a heater fails, the reduction in current will switch the
relay and produce a Evaporator Freezer Alarm (EVAPORA-
TOR_FREEZE, 10001). In addition, the pump signal will ener-
gize. See Appendix H for relay set points. See Fig. 67 for evapo-
rator heater current sensing relay set point adjustment location.
Fig. 67 — Evaporator Heater Set Point Adjustment
To configure this option with the Carrier Controller controls:
NOTE: Evaporator Heater must be configured to YES for the ABVs to
operate.
LOW FLUID TEMPERATURE
The Carrier Controller control is programmed to shut chiller
down if leaving fluid temperature drops below 34°F (1.1°C)
for evaporator fluid type water or below the Brine Freeze Set-
point (Main Menu
Configuration Menu
Service Pa-
rameters
Brine Freeze Setpoint) for the evaporator fluid
type brine. When fluid temperature rises to 6°F (3.3°C) above
the leaving fluid set point, the alarm will reset and the chiller
restarts. Reset is automatic as long as this is the first occur-
rence. For repeat occurrences within 24 hours the alarm must
be manually reset.
LOSS OF FLUID FLOW PROTECTION
All 30XV machines include an integral flow switch that pro-
tects the evaporator against loss of evaporator flow.
TUBE PLUGGING
A leaky tube can be plugged until retubing can be done. The num-
ber of tubes plugged determines how soon the evaporator must be
retubed. All tubes in the evaporator may be removed. Loss of unit
capacity and efficiency as well as increased pump power will re-
sult from plugging tubes. Failed tubes should be replaced as soon
as possible. Up to 10% of the total number of tubes can be plugged
before retubing is necessary. Figure 68 shows an Elliott tube plug
and a cross-sectional view of a plug in place. See Tables 44 and 45
for plug components. If the tube failure occurs in both circuits us-
ing tube plugs will not correct the problem. Contact your local
Carrier representative for assistance.
Fig. 68 — Elliott Tube Plug
Table 44 — Plug Component Parts
(Evaporator Units Only)
*Order directly from Elliot Tool Technologies, Dayton, OH or RCD.
†Can be obtained locally.
Table 45 — Evaporator Tube Components
NOTE: Tubes replaced along heat exchanger head partitions must be
flush with tube sheet (both ends).
DISPLAY
NAME
PATH VALUE
Evaporator
Heater
Installed
Main Menu
Configuration Menu
Factory Parameters
Evap Heater Installed YES/
NO
DEFAULT= NO
IMPORTANT: If unit is installed in an area where ambi-
ent temperatures fall below 32°F (0°C), a suitable corro-
sion-inhibited antifreeze solution or evaporator heater
must be used in the chilled water circuit.
LEGEND
1—
Overcurrent Adjusting Potentiometer
2—
Power Supply Status LED (green)
3—
Relay Output Supply Status LED (yellow)
4—
35 mm Rail Clip-in Spring
a30-5648
CAUTION
Use extreme care when installing plugs to prevent damage to
the tube sheet section between the holes.
COMPONENT PART NUMBER
For Tubes
Brass Pin 853103-1*
Brass Ring
853002-640 or 657* (measure tube ID
before ordering)
Loctite No. 675 †
Locquic “N”†
Roller Extension S82-112/11
COMPONENT
SIZE
in. mm
Tube sheet hole diameter 0.756 19.20
Tube OD 0.750 19.05
Tube ID after rolling (includes
expansion due to clearance.)
0.650 to
0.667
16.51 to 16.94
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