Water Quality Of The Installation - Adisa ADI CD 70 Technical Manual Of Installation, Use And Maintenance

ADI CD boiler - Technical Manual

17.7.5 Water quality of the installation

It is important to follow the instructions indicated in the present manual. The primary circuit of an installation, being a
closed circuit, can not be refilled with non-treated water.
Periodical refillings with non-treated water could cause a constant input of:
Oxygen and dissolved gases (contributing to produce oxidation and corrosion to the installation). This problem
-
can be minimized by installing an air/gas venting in the higher part of the water flow connection or in a common
flow pipe.
Carbonates (contributing to produce scaling in the boilers).
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Due to this reason, water refillings must be reduced to the minimum, and a water meter must be installed in the
refilling of the primary circuit.
It is necessary to take the appropriate precautions with respect to the quality of the water circulating, in order to avoid
corrosion and oxidation of the installation and allow equipments to operate at their maximum performances:
a. Water characteristics
Concept
Lower than 12 ºF
Total
hardness
(TH)
Lower than 100 mg/l
Chloride
between 9.6 and 10
pH
Higher than 2000 Ohms x cm
Resistivity
b. A WATER TREATMENT IS ABSOLUTELY INDISPENSABLE FOR THE INSTALLATION OF THE PRIMARY
CIRCUIT IN THE FOLLOWING CASES:
1. Big installations (with high water contents).
2. Characteristics of the refilling water different from the hardness (TH) indicated in the previous table.
3. Frequent refillings of the installation with new water (because of drainings, water leaks, repairing), even if
the water has a hardness lower than 12ºF.
4. When the maximum volume allowed of refilling water is exceeded (see table).
c. A mesh filter should be installed before each boiler (mesh of 0.3 mm).
d. Air purging/venting:
If the boilers circuit incorporates a common vertical water manifold: place an air vent of big capacity in its higher point.
Otherwise: it would be necessary to install an air vent of big capacity or corrosion inhibitor equipment in a high point of
the circuit behind the boilers.
e. Old installations
e1) Before replacing the existing boilers with new boilers, proceed to clean the installation.
If a chemical product is used, it must be compatible with the installation materials.
Drainage must be made from a low point of the installation, if possible different from the boilers'draining point.
e2) A separator of oxides and sludge must be installed in the circuits'return, so that all the return water flow can pass
through it, allowing its draining without suspending the service.
Apply the considerations of paragraphs "a,b,c,d".
If the circuit is in very bad conditions and the previous measures taken were not sufficient, or the cleaning of the
installation was not efficient, the solution would be to separate the boilers'circuit from the heat emitters'circuit, so that
they are independent one from the other, by means of a plate heat exchanger or similar, according to the hydraulic
diagrams included in this manual (see the corresponding paragraph).
ADISA BY HITECSA disposes of professional staff that, after a visit of the installation, can advise you according to each
case.
These are the values of the circuit water and of the refilling water.
VALUE
allowed of refilling water
Concept
Maximum volume
in the installation
(m3)
Salinity
Conductivity
Iron
VALUE
0.04 x P output / (TH x 0.1)
being:
P output: power output total sum in kW
TH: water hardness in ºF, Ca(HCO3)2
Lower than 50 mg/litre
Lower than 500 µS/cm
Lower than 1 mg/litre
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