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2.3.7 - FILTER
UNICAL suggests the installation of a Y
filter with two gate valves on the return
pipe so that it can be cleaned if neces-
sary. Such filter shall protect the boiler
2.3.8 - BALL VALVES
Unical suggests the installation of ball
gate valves on the system flow/return
pipes. In this case the boiler, if neces-
sary, can be disconnected or drained,
without having to drain the whole sys-
2.3.9 - FEEDING WATER QUALITY
- The system and reinstatement
water chemical-physical features
are fundamental for the boiler cor-
rect operation and safety.
- Among the inconveniences cau-
sed by feeding water low quali-
ties the most frequent and serious
one is the scale deposit on heat
exchange surfaces.
- Less frequent but not less serious
is the water side corrosion of all
heating circuits surfaces.
- It is known that calcareous scales
reduce heat exchange due to the-
ir low heat conductivity, so that
even few mm-thick scales may
cause very dangerous localised
overheating.
- Water treatment is advisable in the
following cases:
A) high hardness of the available
water (> 20°f)
B) very large heating systems
C) high quantities of reinstatement
water due to leakages or mainte-
nance works
- The use of an inhibitor is advisa-
ble to treat feeding waters and to
protect heating systems against
calcareous scales, corrosion and
microbiologic growth. In case of
freezing as well, the use of an anti-
frost together with the inhibitor is
advisable.
- Qualified companies can provide
boiler de-scaling.
tem. A closed expansion vessel, proper-
ly dimensioned and equipped with its
safety valve, shall be fitted between the
gate valves and the boiler.
from the heating system dirt. Its regular
cleaning has to be foreseen.
WARNING!
Never intercept safety devices, such
as safety valve and expansion ves-
sel.
- Any system needs water re-filling
because of evaporation, small or
substantial leakages and mainte-
nance. It is then necessary to cal-
culate the water quantity reque-
sted to avoid new inconveniences
due to untreated water.
To this purpose, the installation of
a water flow-meter is advisable on
reinstatement pipe.
2.3.10- BOILER ANTIFROST
PROTECTION
Should the flow temperature (measured
at global flow temperature NTC) de-
crease under 7°C, the system pump is
set up. Should temperature ulteriorly
decrease (under 3°C), all modules shall
start at min. output until the return tem-
perature reaches 10°C. Such protection
device is exclusively for the boiler. For
the protection of the whole system, a sec-
ond anti-frost thermostat is necessary to
switch on the heating system pump.
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