SPACE HEATING AND DHW
!
C A U T I O N
•
DHW tank supplies hot water from tap water. Domestic hot water is
only used when tap water is connected.
•
For safety, do not add ethylene glycol into water circulation. If added,
water will be contaminated when heat exchanger coil leaks.
•
When water hardness is more than 250-300 ppm, recommend using
softened water to reduce DHW tank scale.
•
Immediately flush DHW tank with fresh water after installation. Flush
once every day in first five days of installation.
•
Try to avoid long runs of water piping between the tank and the DHW
installation in order to decrease possible temperature losses.
lf the domestic cold water entry pressure is higher than the DHW
tank's design pressure, a pressure reducer must be fitted.
•
After used for a while (depend on local water quality and use
frequency), clean DHW tank and remove scales.
a. Power off and close water inlet valve.
b. Open water outlet valve and drainage valve to empty DHW tank.
!
C A U T I O N
When scales are removed, temperature in DHW tank may be a
little high, it should prevent burns or drainage equipment damaged.
c. Close drainage valve after cleaning several minutes with water
inlet valve opened. Ensure effluent water is closed after DHW tank
is full of water. Power on and get back to work.
•
Always check DHW tank and its surroundings has accumulated
water or not. If leak, contact local dealer.
8.5 WATER CONTROL
It is necessary to analyse the quality of water by checking pH,
electrical conductivity, ammonia ion content, sulphur content,
and others. The following is the recommended standard water
quality.
Chilled water system
Circulating
Item
water (20ºC
less than)
Standard Quality pH
(25 °C)
Electrical Conductivity
Less than 40
(mS/m) (25 °C)
Less than 400
{µS/cm} (25 °C)
(2)
Chlorine Ion
Less than 50
(mg CI
/I)
¯
Sulphur Acid Ion
Less than 50
(mg H
SO
/I)
¯
2
4
The amount of Acid
consumption (pH 4.8)
Less than 50
(mg CaCO
/I)
3
Total Hardness
Less than 70
(mg CaCO
/I)
3
Calcium Hardness
Less than 50
(mg CaCO
/I)
3
Silica L (mg SIO
/I)
Less than 30
2
Reference Quality
Less than 1.0
Total Iron (mg Fe/I)
Total Copper
Less than 1.0
(mg Cu/I)
Sulphur Ion (mg S
/I)
It shall not be detected
2¯
Ammonium Ion
Less than 1.0
(mg NH
/I)
+
4
Remaining Chlorine
Less than 0.3
(mg CI/I)
Floating Carbonic
Less than 4.0
Acid (mg CO
/I)
2
Index of Stability
?
N O T E
• (1) The mark " " in the table means the factor concerned with the
tendency of corrosion or deposits of scales.
• (2) The value showed in "{}" are for reference only according to the
former unit.
21
Tendency
Supply
Corro-
water
sion
6.8 ~ 8.0
6.8 ~ 8.0
Less
than 30
Less
than 300
Less
than 50
Less
than 50
Less
than 50
Less
than 70
Less
than 50
Less
than 30
Less
than 0.3
Less
than 0.1
Less
than 0.1
Less
than 0.3
Less
than 4.0
6.8 ~ 8.0
-
(1)
Depos-
its of
scales