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5.
sTArT-UP
IMPOrTAnT
Before start-up, fully insert the flue gas agitators, taking care that they are pushed inside by at least 100 mm.
5.1. Preliminary checks
Before starting-up the boiler check that
• The plate data corresponds with the electrical power, hydraulic and liquid or gas fuel supply;
• The power range of the burner is compatible with that of the boiler.
• The instructions for the boiler, as well as for the burner, are available in the boiler room.
• The chimney functions properly.
• The air vent present is sufficiently large and free of obstacles.
• The door, flue chamber and burner plate are properly closed so as to guarantee flue sealing in all parts of the boiler.
• The system is full of water and that any air pockets have been eliminated.
• Anti-freeze measures have been taken.
• The circulating pumps function correctly.
• The expansion vessel and the safety valve(s) are correctly connected (without any locking device) and function properly.
• Check electrical parts and that thermostats function properly.
5.2.
Water treatment
The most common phenomena occurring in thermal systems
are:
Lime incrustations
Lime incrustations interfere with the thermal exchange
between the combustion gases and water, causing an
abnormal increase in the temperature of the parts exposed
to flame and therefore, a noticeable reduction in the life-
span of the boiler.
Lime becomes concentrated at the points where the wall
temperature is the highest. The best prevention measure is,
therefore, the elimination of areas of over-heating.
The incrustations form a non-conductive layer which reduces
the thermal exchange of the generator, diminishing the
efficiency.
This means that a substantial part of the heat obtained by
combustion is not fully transferred to the water in the system
but escapes via the chimney.
Water side corrosion
The corrosion of the metal surfaces of the boiler on water side is due to ions of the iron solution passing through the system (Fe+).
The presence of dissolved gases, in particular oxygen and carbon dioxide, has a significant role in this process.
Often corrosive phenomena are seen in softened and/or demineralised water which by nature is already more aggressive towards
iron (acid water with pH < 7). In these cases, incrustation is avoided but not corrosion and it is necessary to treat the water itself with
corrosive process inhibitors.
5.3.
Filling the system
Water must enter the heating system as slowly as possible and in quantities proportional to the air release capacity of the relevant
components.
The filling time varies according to the size of the system but is never less than 2 or 3 hours.
In the case of a closed expansion vessel system, water must be added until the arrow on the manometer reaches the static pressure
value pre-set by the vessel.
Proceed to initial water heating to the maximum temperature permitted by the system but never exceeding 90°C.
During this operation the air in the water is released via automatic or manual air separators fitted in the system. Once the air release
is complete, restore the pressure to the pre-set value and close the manual and/or automatic supply tap.
24
%
30
20
10
0
5
%
% fuel not utilised
mm mm of lime
Lime graph
10
15
20
mm
fig. 19
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