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16
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
compression tank to the system. This is the only location in the
system where pump operation will not give erroneous pressure
indications 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. On units with the hydronic package, this can best
be done using the balancing valve.
In order to adjust the balancing valve, put a differential
pressure gage across the pressure taps on the valve. Make sure
that all system isolation and control valves are open. Use
Tables 4A-5B or a Bell & Gossett balancing valve calculator to
determine gpm. To read Tables 4 and 5:
1. Measure the pressure drop across the balancing valve. If
the pressure reading is in psig, multiply psig by 2.31 to
convert to feet of water before using Tables 4A and 5A.
2. Go to the row in the chart corresponding to the setting on
the valve, interpolating if necessary.
3. The gpm corresponding to the pressure drop measured is
the flow through the balancing valve.
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
30RAP balancing valve to maintain design flow plus 10%
through the chiller.
A rough estimate of water flow can also be obtained from
the pressure gages across the 30RAP heat exchanger.
Figures 16A-17B show the relationship between gpm and heat
exchanger pressure drop. It should be noted that these curves
are for “clean” heat exchangers; they do not apply to heat ex-
changers with fouling. To read the chart, subtract the readings
of the two pressure gages on the hydronic kit. This number is
the pressure drop across the heat exchanger. Adjust the factory-
installed balancing valve or external balancing valve (units
without hydronic package) until the correct pressure drop is ob-
tained for the required gpm. Total unit pressure drop is found in
Appendix A.
Minimum Loop Volume
— The minimum volume of fluid re-
quired to be in circulation is a function of the number of com-
pressors in the chiller as well as the type of application. The
minimum fluid in circulation must equal or exceed the values
in the following table. See Table 6.
To achieve this fluid volume, it is often necessary to install a
tank in the loop. The tank should be baffled to ensure there is
no stratification and that water (or brine) entering the tank is
adequately mixed with liquid in the tank. See Fig. 18.
A properly baffled storage tank is available from the factory
as an accessory. These tanks are designed to physically fit
beneath the corresponding 30RAP unit, taking up the same
footprint.
• 30RAP010-018 83 gallons (314 liters)
• 30RAP022-030 119 gallons (450 liters)
• 30RAP035-060 241 gallons (912 liters)
Storage tank weight (water weight included) is as follows:
• 30RAP010-018 1673 lb (759 kg)
• 30RAP022-030 2193 lb (995 kg)
• 30RAP035-060 4361 lb (1978 kg)
Maximum Loop Volume (Units with Hydronic Package)
—
Since the minimum size of the expansion tank is dependent
upon loop volume, units with the integrated hydronic kit must
not exceed the maximum loop volume limits below (see
Table 7). The limits are dependent on the maximum and mini-
mum temperatures of the water, the maximum and minimum
pressures seen by the expansion tank, and the heat transfer flu-
id. Expansion tank and maximum loop volume data is as
follows.
30RAP010-030 30RAP035-060
Volume gal (L) 5.0 (18.9) 10.0 (37.9)
Acceptance Volume gal (L) 2.9 (11.0) 5.5 (20.8)
x
x
DILUTED
CLEANING
AGENT
SYSTEM
POT FEEDER AND
TRANSFER PUMP
30RA UNIT
TO DRAIN
TEMPORARY
PUMP
TEMPORARY
BYPASS
x
x
DILUTED
CLEANING
AGENT
SYSTEM
SIDE
STREAM
FILTER
POT FEEDER AND
TRANSFER PUMP
30RA UNIT
TO DRAIN
TEMPORARY
PUMP
TEMPORARY
BYPASS
Fig. 14 — Typical Set Up for Cleaning Process
Fig. 15 — Cleaning Using a Side Stream Filter