Evaporator Pump Control; Preparation For Year-Round Operation - Carrier AquaForce 30XV140-500 Installation Instructions Manual

IMPORTANT: Automatic vents should be located in
accessible locations for maintenance purposes and
should be protected from freezing.
EVAPORATOR PUMP CONTROL — It is required that
evaporator pump control be utilized on all chillers unless the
chilled water pump runs continuously or the chilled water sys-
tem contains a suitable antifreeze solution.
CAUTION
Applications that utilize fresh water as the circulated fluid
require that the circulating pump be controlled directly by
the chiller. Operation with fresh water is not fail-safe
should there be a loss of power to the chiller or to the circu-
lating pump. Freeze damage due to power loss or disabling
chiller pump control in fresh water systems will impair or
otherwise negatively affect the warranty.
Refer to the control and power wiring schematic on page 103
for proper connection of the evaporator pump (PMP1 and
PMP2). The evaporator pump output will remain energized for
30 seconds after all compressors stop due to an OFF com-
mand. In the event a freeze protection alarm is generated, the
evaporator pump output will be energized regardless of the
evaporator pump control software configuration. The evapora-
tor pump output is also energized when certain alarms are gen-
erated. A thermal flow sensor is factory installed in the
entering fluid nozzle to prevent operation without flow through
the evaporator. See Fig. 40. The flow sensor is factory wired.
Proper software configuration of the evaporator pump control
parameters is required to prevent possible evaporator freeze-
up. Refer to the Controls, Start-Up, Operation, Service and
Troubleshooting guide for more information.
4.2 in. (107 mm)
HEX WRENCH
7/8 in. (22 mm)
Fig. 40 — Thermal Flow Sensor
If evaporator pump control is not utilized, it is required that the
chiller be electrically interlocked with the chilled water pump
starter. The interlock should be wired to terminals TB5-27 and
TB5-28. It is also recommended that the evaporator pump out-
put be used as an override to the chilled water pump control
circuit to provide additional freeze protection. See the Field
Control and Power Wiring figure on page 103.
PREPARATION FOR YEAR-ROUND OPERATION — In
areas where the piping or unit is exposed to 32F (0C) or
lower ambient temperatures, freeze-up protection is required
using inhibited glycol or other suitable corrosion-resistant anti-
freeze solution and electric heater tapes. Heater tapes on piping
should have a rating for area ambient temperatures and be cov-
ered with a suitable thickness of closed-cell insulation. Route
power for the heater tapes from a separately fused disconnect.
Mount the disconnect within sight from the unit per local or
NEC (National Electric Code) codes. Identify disconnect at
heater tape power source with a warning that power must not
be turned off except when servicing unit.
A drain connection is located at the bottom of the evaporator
head. See Fig. 37 for connection location. Install shut-off
valves to the drain line before filling the system with fluid.
Low Ambient Temperature Head Pressure Control — For
units intended to operate in low ambient conditions,
field-fabricated and field-installed wind baffle is re-
quired if the wind velocity is anticipated to be greater
than 5 mph (8 km/h). Wind baffle should be constructed
with minimum 18-gage galvanized sheet metal or other
suitable corrosion-resistant material with cross breaks for
strength. See Fig. 41. Use field-supplied screws to attach
baffle to the corner posts of the machine. Be sure to hem
or turn a flange on all edges to eliminate sharp edges on
the baffles.
Mount baffle opposite control box end. It is recommended that
the upper notches be used for mounting the baffle. This
reduces the risk of damaging the coil while drilling a mounting
hole. Loosen the upper corner post bolts and slide the baffle
under the bolt and washer. Tighten the bolt. Drill holes in the
bottom of the flange of the baffle and mount with two screws
0.87 in.
(22 mm)
to secure the bottom of the baffle to the corner post.
98
IMPORTANT: Adding antifreeze solution is the only
certain means of protecting the unit from freeze-up if
heater fails or electrical power is interrupted or lost
while temperatures are below 32F (0C).
WARNING
Disconnect all power to the unit before performing mainte-
nance or service. Electrical shock and personal injury could
result.
CAUTION
To avoid damage to the refrigerant coils and electrical com-
ponents, use extreme care when drilling screw holes and
screwing in fasteners.