Table of Contents
Advertisement
SYSTEM
DILUTED
CLEANING
AGENT
a30-5289
Fig. 19 — Typical Set Up for Cleaning Process
SYSTEM
DILUTED
SIDE
CLEANING
STREAM
AGENT
FILTER
a30-5290
Fig. 20 — Cleaning Using a Side Stream Filter
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 [28 kPa] 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 pres-
sure 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 con-
nection is close to the expansion tank. An air vent should be in-
stalled 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 pro-
tection of the city water system should be consulted and followed
to prevent contamination of the public water supply. This is espe-
cially important when antifreeze is used in the system.
POT FEEDER AND
TRANSFER PUMP
x
TEMPORARY
30RAP UNIT
PUMP
x
TEMPORARY
BYPASS
TO DRAIN
POT FEEDER AND
TRANSFER PUMP
x
TEMPORARY
30RAP UNIT
PUMP
x
TEMPORARY
BYPASS
TO DRAIN
Set Water Flow Rate
Once the system is cleaned, pressurized, and filled, the flow rate
through the chiller must 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 sys-
tem isolation and control valves are open. Use Tables 13 and 14 to
determine gpm.
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 13 and 14.
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 30RC bal-
ancing 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 30RC heat exchanger. Figures 21-24
show the relationship between gpm and heat exchanger pressure
drop. It should be noted that these curves are for "clean" heat ex-
changers; they do not apply to heat exchangers 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 obtained for the required gpm. Total unit pressure
drop is found in Appendix A.
Water Treatment
Fill the fluid loop with water (or suitable inhibited antifreeze solu-
tion) and a corrosion-resistant inhibitor suitable for the water of
the area. Consult the local water treatment specialist for character-
istics of system water and a recommended inhibitor for the evapo-
rator fluid loop.
Untreated or improperly treated water may result in corrosion,
scaling, erosion, or algae. The services of a qualified water treat-
ment specialist should be obtained to develop and monitor a treat-
ment program.
Water must be within design flow limits, clean, and treated to
ensure proper chiller performance and reduce the potential of
tube damage due to corrosion, scaling, erosion, and algae.
Carrier assumes no responsibility for chiller damage resulting
from untreated or improperly treated water.
30
CAUTION
Advertisement
Table of Contents
