WFC- SC(H) Series
.
Installation
- 18 -
6 Water Quality
6.1
General
Water used in the chilled-hot water circuit and cooling water circuit may cause
corrosion if not properly analyzed and treated to maintain a passive condition. The
cooling water circuit is particularly vulnerable since in most cases, this is an open
circuit thus lending itself to scaling from precipitation of dissolved solids, and to
growth of algae and micro-organisms in the water. All have a detrimental effect on
the function of rejecting heat. If left unchecked, moreover, performance of the chiller-
heater will be affected and a significant reduction in life expectancy could result. It is
equally important to consider that extreme health hazards may attend badly
maintained cooling towers
Correct and continuous water treatment is thus essential to the correct operation of the
chiller-heater. Failure to provide and maintain in operation the necessary apparatus for
water treatment will immediately void the warranty applying to the absorption
machine.
6.2
Water Quality Limits
The following table describes the maximum limits of water contaminates within the
circuits of the chiller-heater. Make-up water, exhibiting total dissolved solids no
greater than 50ppm, with substantial “bleed-off”, would be necessary to achieve this
result in the cooling water circuit.
If such water quality in supply is not available under all circumstances, chemical
treatment is required to combat scaling. Chemicals to combat algae and micro-
organisms are in any event necessary. It is highly recommended that water treatment
specialists be retained prior to the initial commissioning of the plant and to provide an
ongoing program of chemicals and periodic inspections to ensure that the cooling
water circuit remains safe and compatible throughout.
Water Quality Reference Table
ITEM
CHILLED/
HOT WATER
HEAT
MEDIUM
COOLING
WATER
MAKE UP
WATER
pH (at 25 °C)
6.8-8.0
7.0-8.0
6.5 – 8.2
6.8 – 8.0
Conductivity (µS/cm at 25°C)
400
300
800
300
Chloride ion (Cl
-
ppm)
50
30
200
50
Sulfate ion (SO
4
2-
ppm)
50
30
200
50
Acid consumption (CaCO
3
ppm)
50
50
100
50
Total hardness (CaCO
3
ppm)
70
70
200
70
Calcium hardness (CaCO
3
ppm)
50
50
150
50
S
ta
n
d
a
rd
Ionic silica (SiO
2
ppm)
30
30
50
30
Total iron (Fe ppm)
1.0
1.0
1.0
0.3
Copper (Cu ppm)
1.0
1.0
0.3
0.1
Sulfide ion (S
2-
ppm)
N.D.
N.D.
N.D.
N.D.
Ammonium ion (NH
4
+
ppm)
1.0
0.1
1.0
0.1
Residual chlorine (Cl ppm)
0.3
0.1
0.3
0.3
Free carbon dioxide (CO
2
ppm)
4.0
0.4
4.0
4.0
R
ef
er
en
ce
Ryzner stability index
-
-
6.0 - 7.0
-
N.D. (Not Detectable)
Caution.
Operating the chiller-heater in cooling mode without cooling water treatment
equipment installed, applied with chemicals and operating correctly will void
the warranty.
