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HYDRAULIC SYSTEM
25
Chapter 6
Where it is necessary to separate the individual heat generator from the expansion vessel or expansion
vessels unit, a three-way tap must be applied on the connection piping between the generator and the
vessel, in order to ensure, in every position, the connection of the generator with the expansion vessel or
with the atmosphere.
The expansion vessels, the connecting pipes, the bleed pipes and drain pipes must be protected from
freezing, where this phenomenon occurs. The solution used for this purpose is described in the design.
COMMISSIONING CHECKS
Before connecting the boiler arrange:
a) an accurate washing of all plant piping in order to remove any residues which might compromise the
correct functioning of certain plant components (pumps, valves, etc.).
b) a check to verify that the fl ue as adequate draft, is not narrowed and that other appliances do not
discharge into the fl ue.
This is to prevent unexpected power increases. Only after this control can the fl ue fi tting be mounted
between the boiler and the fl ue.
A check of the connections with pre-existing fl ues is recommended.
FEEDING WATER FEATURES
The chemical-physical features of the plant and reinstate water are fundamental for the correct functioning
and life-span of the boiler.
Amongst the inconveniences caused by bad quality feeding water, the most frequent is the scaling of the
thermal exchange surfaces.
Less frequent, but equally serious, is the corrosion of the water side surfaces of the entire circuit.
It is known that the limescale scalings, even if there are only a few millimetres, due to their low thermal
conductivity, greatly reduce the thermal exchange, determining damaging located heating. It is strongly
recommended in the following cases to treat the water:
a) very hard water available (higher than 20°f )
b) very extended plants
c) large water quantities restored due to leaks
d) subsequent fi llings due to plant maintenance work
To treat the feeding water of the heating plants, it is recommended to always contact specialised
companies.
FILLING THE PLANT
Once the hydraulic connections have been carried out, proceed to connecting the plant.
Open all air venting valves of radiators, boiler and plant.
Gradually open the load cock ensuring that the air venting valves work regularly. Using the manometer,
check that the plant is pressurised. In case of closed vessel plant, reach the pressure of about 0.11 – 0.12 MPa
(1.1 – 1.2 bar). For open vessel plants, the pressure in the lowest part of the boiler is given by the height of
the vessel. Close the load cock and again release the air from the boiler through the venting valve.