37
Step 6 — Fill the Chilled Water Loop
WATER SYSTEM CLEANING — Proper water system
cleaning is of vital importance. Excessive particulates in the
water system can cause excessive pump seal wear, reduce or
stop flow, and cause damage of other components. Water
quality should be maintained within the limits indicated in
Table 10. Failure to maintain proper water quality may result in
heat exchanger failure.
Table 10 — Water Quality Characteristics
and Limitations
*
Sulfides in the water
q
uickly oxidize when exposed to air, re
q
uiring that
no agitation occur as the sample is taken. Unless tested immediately
at the site, the sample will re
q
uire sta
b
ilization with a few drops of one
Molar zinc acetate solution, allowing accurate sulfide determination up
to 24 hours after sampling. A low pH and high alkalinity cause system
pro
b
lems, even when
b
oth values are within the ranges shown. The
term pH refers to the acidity,
b
asicity, or neutrality of the water supply.
Below 7.0, the water is considered to
b
e acidic. A
b
ove 7.0, water is
considered to
b
e
b
asic. Neutral water has a pH of 7.0.
†Dissolved car
b
on dioxide can either
b
e calculated from the pH and
total alkalinity values, shown
b
elow, or measured on the site using a
test kit. Dissolved Car
b
on Dioxide, PPM = TA x 2
[(6.3-pH)/0.3]
where TA
= Total Alkalinity, PPM as CaCO
3
.
To perform proper water system cleaning perform the follow-
ing steps:
1. Install a temporary bypass around the chiller to avoid cir-
culating dirty water and particulates into the pump pack-
age and chiller during the flush. Use a temporary circulat-
ing pump during the cleaning process. Also, be sure that
there is capability to fully drain the system after cleaning
2. Be sure to use a cleaning agent that is compatible with all
system materials. Be especially careful if the system
contains any galvanized or aluminum components. Both
detergent-dispersant and alkaline-dispersant cleaning
agents are available.
3. It is a good idea to fill the system through a water meter.
This provides a reference point for the future for loop
volume readings, but it also establishes the correct
quantity of cleaner needed in order to get the required
concentration.
4. Use a feeder/transfer pump to mix the solution and fill the
system. Circulate the cleaning system for the length of
time recommended by the cleaning agent manufacturer.
a. After cleaning, drain the cleaning fluid and flush the
system with fresh water.
b. A slight amount of cleaning residue in the system can
help keep the desired, slightly alkaline, water pH of 8
to 9. Avoid a pH greater than 10, since this will
adversely affect pump seal components.
c. A side stream filter is recommended (see Fig. 38)
during the cleaning process. Filter side flow rate
should be enough to filter the entire water volume
every 3 to 4 hours. Change filters as often as neces-
sary during the cleaning process.
d. Remove temporary bypass when cleaning is
complete.
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 (4 psig is usually 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.
CAUTION
Failure to properly clean all piping and components of the
chilled water system before unit start-up may result in
plugging of the heat exchanger, which can lead to poor per-
formance, nuisance alarms and damage from freezing.
Freezing damage caused by an improperly cleaned system
represents abuse and may impair or otherwise negatively
affect the Carrier product warranty.
WATER CHARACTERISTIC
QUALITY LIMITATION
Alkalinity (HCO
3
-
)
70 – 300 ppm
Sulfate (SO
4
2-
)
Less than 70 ppm
HCO
3
-
/SO
4
2-
Greater than 1.0
Electrical Conductivity
10 – 500
S/cm
pH
7.5 – 9.0
Ammonia (NH
3
)
Less than 2 ppm
Chlorides (Cl
-
)
Less than 300 ppm
Free chlorine (Cl
2
)
Less than 1 ppm
Hydrogen Sulfide (H
2
S)*
Less than 0.05 ppm
Free (aggressive) Carbon Dioxide (CO
2
)†
Less than 5 ppm
Total Hardness (°dH)
4.0 – 8.5
Nitrate (NO
3
)
Less than 100 ppm
Iron (Fe)
Less than 0.2 ppm
Aluminum (Al)
Less than 0.2 ppm
Manganese (Mn)
Less than 0.1 ppm
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. 37 — 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. 3
8
— Cleaning Using a Side Stream Filter
a30-5048
