3
3
60T - 280T
COSMOGAS
10.5 - Expansion tank connection
ATTENTION !!! The appliance does not have
an expansion tank. Provide the system with an
appropriately sized expansion tank as required by the
national and local installation standards.
10.6 - Supply and return
ATTENTION !!! COSMOGAS is not liable for any
damage caused by incorrect use of additives in the
heating system.
ATTENTION !!! The system downstream of
the appliance must be built with materials that resist
temperatures up to 97°C and 11 bar of pressure.
Otherwise (i.e. plastic piping), the system must be
equipped with appropriate protection and safety
devices.
Before making the hydraulic connections, wash the system
thoroughly to remove any slag (hemp, radiator foundry
sands, etc.) that could damage the appliance. The system
must also be washed if an appliance is replaced.
You can check the positioning of the supply and return
fittings in figures 8-1 and 8-2.
Install a metal mesh filter with a 1 mm
2
opening on the
return pipe in order to stop any system residues before
they go back into the appliance.
Do not use the appliance to introduce any type of
additives into the system.
10.7 - Boiler water supply
ATTENTION !!! The system (and, therefore,
the appliance) must be connected to the water mains
interposing a device to prevent backwash into the
potable water system, as required by the pollution
prevention safety standards in force.
10.7.1 - Recommendations on the
characteristics of the water used in the
system
Filling the heating system is an extremely delicate operation
that must not be underestimated, both when simply replacing
the heat generator as well as for new installations. A mistaken
assessment of the system water characteristics can, in certain
cases, lead to damages to the system and heating module. A
system is almost never perfectly sealed; at times, there can
be water leaks or oxygen inlets. Both of these phenomena
are harmful.
Of the parameters that can negatively impact the life of a
system, the main ones are:
- The simultaneous presence of different metals (copper,
brass, steel and aluminium) that, in a watery environment,
lead to galvanic corrosion.
- The presence of free oxygen, due to air leaks that form near
fittings or gaskets, is a typical corrosive agent, particularly
active at temperatures between 50 and 70°C.
- Water loss, leading to frequent top-ups, can lead both to
corrosion as well as scale build-up, depending on the type of
water available for the top-ups. In any case, the extent of the
leaks (and corresponding top-ups) must be kept under control,
especially when an automatic filling system is installed. In this
case, installing a counter indicating the amount of water that
is reintegrated is highly recommended.
Natural or additional impurities in the water. Many types of
drinking water can contain even considerable concentrations
of chlorides and sulphates that can increase how quickly
the metal surfaces corrode. Other undesirable components
could have got into the system before or during installation
(construction materials, metal shavings, sawdust, grease,
deposits, and dirt in general). Welding residues can also
cause corrosion, both in new systems as well as in the event
of modifications or repairs. In old systems designed to work
with radiators, featuring very large pipe diameters, the water
content is considerable and favours the formation of sludge
and deposits.
Sludge and scale build-up Black deposits (magnetite) indicate
that corrosion is limited. However, the high specific gravity
of this oxide can create clogs that are difficult to remove,
especially in the hotter areas. Scale build-up is due to water
hardness, that is, the presence of calcium and magnesium
minerals. Calcium, in the form of carbonate, falls on the hotter
areas of the system. Magnetite often contributes in intensifying
the scale build-up. Iron oxide (the water has a reddish colour),
instead, is a sign of oxygen corrosion.
Frequent leaks. In the event of frequent leaks, hydrogen and/
or air accumulates on the high part of the exchanger and
the radiators, preventing complete heat exchange. When
the electrolytic corrosion process begins, the water level in
the system goes down, gases accumulate in the high part
of the heat exchanger and on the radiators. The presence
of air is caused by the fact that the system might not be
perfectly sealed. Slow system pressure loss due to a leak
is often difficult to find, especially when the breach is very
small (during winter, leaks on the radiator valves are often
not visible as the heat generated by the radiator or the boiler
dry them). However, these micro-leaks allow air to get into
the system. The main points that can lead to micro-leaks are
found in the joints and, in particular, on the circulator intake
side (air bleed valve, seals with o-rings, loading valves). In
these cases, to avoid damage, the system must be protected
with an appropriate corrosion inhibitor.
10.7.2 - For the system to operate properly,
you must make sure that:
1) the system has no leaks or, at the least, the most evident
leaks have been removed;
2) if there is an automatic filling system, a litre counter must
have been installed in order to accurately know the extent of
any leaks;
3) system filling and top-ups are done with softened water to
reduce the overall hardness. The water
must
also be treated
in order to keep the pH within the required threshold to prevent
corrosion;
4) Both in new systems and for replacements, the system
must be equipped with efficient devices that eliminate air and
impurities: filters, micro-impurity separators and micro-air
bubble separators;
5) Avoid draining system water during scheduled maintenance,
even seemingly insignificant amounts: for example, to clean
the filters, equip the system with specific shut-off valves
upstream and downstream of the filter itself;
6) Always analyse the system water before opening
communication between the new generator and the system
to establish whether the chemical and physical characteristics
of the water indicate you should completely drain the system,
use the water already in the system, or chemically wash the
system using water from the mains plus a cleaning solution
when there is the suspicion that the system might be dirty or
10 - INSTALLATION - Hydraulic connections - boiler