15
FILLING THE SYSTEM — The initial fill of the chilled
water system must accomplish three purposes:
1. The entire piping system must be filled with water.
2. The pressure at the top of the system must be high enough
to vent air from the system (usually 4 psig is adequate for
most vents).
3. The pressure at all points in the system must be high
enough to prevent flashing in the piping or cavitation in
the pump.
The pressure created by an operating pump affects system
pressure at all points except one, the connection of the com-
pression tank to the system. This is the only location in the sys-
tem where pump operation will not give erroneous pressure in-
dications during the fill. Therefore, the best location to install
the fill connection is close to the expansion tank. An air vent
should be installed close by to help eliminate air that enters
during the fill procedure.
Ensure the following when filling the system:
1. Remove temporary bypass piping and cleaning/flushing
equipment.
2. Check to make sure all drain plugs are installed.
3. Open the blow-down valve to flush the strainer.
Normally, a closed system needs to be filled only once. The
actual filling process is generally a fairly simple procedure. All
air should be purged or vented from the system. Thorough
venting at the high points and circulation at room temperature
for several hours is recommended.
NOTE: Local codes concerning backflow devices and other
protection of the city water system should be consulted and
followed to prevent contamination of the public water
supply. This is especially important when antifreeze is used
in the system.
Set Water Flow Rate — Once the system is cleaned, pressur-
ized, and filled, the flow rate through the chiller needs to be
established.
NOTE: Carrier recommends a differential pressure gage when
measuring pressures across the pumps or balancing valves.
This provides for greater accuracy and reduces error build-up
that often occurs when subtracting pressures made by different
gages.
On primary/secondary systems, it is advisable to set the
30MP balancing valve to maintain design flow plus 10%
through the chiller.
A rough estimate of water flow can also be obtained from
measuring the pressure drop across the 30MP heat exchanger.
Figures 12 and 13 show the relationship between gpm (l/s) and
heat exchanger pressure drop. It should be noted that these
curves are for “clean” heat exchangers; they do not apply to
heat exchangers with fouling. Adjust the external balancing
valve until the correct pressure drop is obtained for the required
gpm.
Step 7 — Make Electrical Connections —
All
field wiring must comply with local code requirements.
Electrical data for the complete unit and for the compressors is
shown in Table 8. See Fig. 17 for field wiring connections. A
field-supplied branch circuit disconnect switch that can be
locked in either OPEN or OFF position
must
be installed.
Control circuit power is 24 v on all units. Factory-installed
control transformer (TRAN 1) uses line voltage for all units.
All control transformers are factory-installed and wired. For
208/230-3-60 units operating at 208-3-60 line voltage, TRAN1
primary connections must be moved to terminals H3 and H4.
Inside the control box are terminals for field power and
ground (earth) wiring. A ground wire must be installed with
each field power supply. Compressors are wired for across-the-
line start. Refer to Table 8 for electrical data.
FLOW SWITCH — A condenser flow switch is available as
an accessory for all 30MPW units, and can be field-installed.
The Carrier flow switch accessory (part no. 30MP-900---004)
is available for this purpose. Flow switch wiring terminals are
located in the field wiring compartment of the control box. The
flow switch should be wired between terminals LVT-16 and
LVT-17 for all units.
CONTROL BOX, POWER SECTION — The electrical
power supply is brought in through the top left-hand side of the
control box. Pressure-lug connections on the terminal blocks
are suitable for only for copper conductors.
The control box power section contains the following
components:
• power terminal block
• optional disconnect switch
• compressor circuit breaker(s)
• compressor contactor(s)
• current sensor boards
• control transformer
• ground lug
• neutral terminal (380-3-60 units only)
• crankcase heater relay (30MPA units only)
• fuses
CONTROL BOX, CONTROLS SECTION — The control
box controls section contains the following components:
• main base board (MBB)
• scrolling marquee display
• optional energy management module
• control-circuit breakers for 24-v circuits
• control-circuit ON-OFF switch
• unit Enable/Off/Remote contact switch
• unit Alarm/Alert indicator light
CONTROL BOX, FIELD CONTROL WIRING SEC-
TION — Inside this section is the low-voltage, field-wiring
terminal strip (LVT). All low-voltage field-wiring connections
are made to this terminal block. There are three
7
/
8
-in. (22 mm)
knockouts provided for field wiring in this section.
x
x
DILUTED
CLEANING
AGENT
S
Y
S
TEM
POT FEEDER AND
TRAN
S
FER PUMP
3
0MP UNIT
TO DRAIN
TEMPORARY
PUMP
TEMPORARY
BYPA
SS
Fig. 15 — Typical Set Up for Cleaning Process
a30-5047
x
x
DILUTED
CLEANING
AGENT
S
Y
S
TEM
S
IDE
S
TREAM
FILTER
POT FEEDER AND
TRAN
S
FER PUMP
3
0MP UNIT
TO DRAIN
TEMPORARY
PUMP
TEMPORARY
BYPA
SS
Fig. 16 — Cleaning Using a Side Stream Filter
a30-5048
