SystemAir AQVC 105, Installation And Maintenance Manual

Page: 15 / 62

Page 14
4.3 External Water Circuit
The flow switch and the filter water, although not in-
cluded in the supply, must always be fitted such as
plant components.
Their installation is mandatory for warranty.
The external water circuit shall guarantee a
constant water flow rate through the circulat-
ing refrigerant/water heat exchanger (evap-
orator) under steady operating conditions
and in case of a load variation.
The circuit shall be composed by the following ele-
ments:
n
A circulation pump which can ensure the necessary
flow rate and head.
n
The total content of the primary water circuit shall
never be lower than 2.5 lt/kW in terms of refriger-
ating capacity. If the total water volume in the pri-
mary circuit should be unable to reach such a value,
an additional heat-insulated storage tank should be
installed. This tank is intended to avoid any repeti-
tive start of the compressor.
n
A membrane expansion tank complete with a safety
valve and a drain which shall be visible.
The expansion tank shall be dimensioned in
such a way that it can absorb a 2% expan-
sion of the total volume of the water in the
plant (exchanger, pipelines, uses and stor-
age tank, if available). The expansion tank
shall never be insulated when the circulating
fluid is not flowing through it.
A differential pressure switch is mounted as a stand-
ard. It will stop the unit whenever it senses a load loss
through the heat exchanger which may result in a flow
rate problem.
In addition:
n
Install on/off valves (accessory) on the lines at the
inlet and outlet of the manifolds of the exchangers
(evaporator).
n
Arrange a by-pass complete with an on/off valve
between the manifolds of the heat exchangers.
n
Arrange air vent valves at the high points of the wa-
ter lines.
n
Arrange drain points complete with plugs, clocks,
etc. in the proximity of the low points of the water
lines.
n
Insulate the water lines to prevent the heat from
blowing back into the unit.
WARNING
NOTE
Installation
RECOMMENDED WATER COMPOSITION
PH 7,5 - 9
Electrical conductivity 10 - 500 μS/cm
Total hardness 4,5 - 8,5 dH
Temperature < 60 [°C]
Alkalinity (HCO
3
-
) 70-300 ppm
Alkalinity / Sulphates (HCO
3
-
/ SO
4
2-
) > 1 ppm
Sulphates (SO
4
2-
) < 70 ppm
Chlorides (Cl
-
) < 50 ppm
Free Chlorine < 0,5 ppm
Phosphates (PO
4
3-
) < 2 ppm
Ammonia (NH
3
) < 0,5 ppm
Ammonium Ion (NH
4
+
) < 2 ppm
Manganese Ion (Mn
2+
) < 0,05 ppm
Free Carbon Dioxide (CO
2
) < 5 ppm
Hydrogen Sufide (H
2
S) < 0,05 ppm
Oxygen Content < 0,1 ppm
Nitrates (NO
3
-
) < 100 ppm
Manganese (Mn) < 0,1 ppm
Iron (Fe) < 0,2 ppm
Aluminium (Al) < 0,2 ppm
Caution
If the water circuit is to be drained for a time exceeding one month, the
circuit must be fully charged with nitrogen to prevent any risk of corrosion
by differential venting