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Hartley and Sugden
4. Hydraulic installation of the boiler
General points
The installer must provide a safety valve in the flow outlet prior to any valve or connection to any hydraulic appliance.
The installation must be designed in such a way that the filling and addition of water to the system takes place as infrequently
as possible and must always be strictly controlled. Any uncontrolled automatic filling of the system is prohibited.
Should the boiler be connected to an existing heating installation, it is necessary to carry out a careful flushing of the system
in order to eliminate all impurities andsludge deposit whi chmaybe present. Such deposits, if allowed to remaincould accumulate
in the boiler and cause overheating, corrosion and noises.
In order to avoid the complete emptying of the system (in the eventof problems occurringwiththe boiler or theheating circuit),
We recommend :
- the installation o f isolating valves on the boiler flow an d re turn connections.
- hydraulic insulation o f one of several circulating pumps.
All necessary precautions must be taken to prevent :
- Gases accumulation in the top part of the b oiler
- Deposits of sludge in the bottom part of the boiler.
Filling of the installation
Prior to the final filling of the installation we reco mmend on both existing and new installations that the system is completely
flushed out and at the same time the water tightness of the system and hydraulic components verified.
The maximum hydraulic operating pressure is (4 bar ( 4kg/cm
2
). However, it may prove necessary to adapt the operating
pressure acco rding to the characteristics of the installatio n, circulating pump and pressure of the expansion tank. With
nitrogen the cold installation pressure must ALWAYS be higher than the nitrogen pressure of the expansion tank.
During fill ing and when water is added to the system it will always be necessary to vent the air from the inst allation.
Significant additionsof waterto the installation maybring about premature deterioration of the boiler witha depo sit of mineral
substances present in t he water. These deposi ts lead to thermal and mechanical constraints, which may go as far as resulting
in the cracking of the cast iro n secti o ns of the boi ler.
Characteristics of the water in the heating circuit
In order to avoid all harmful furring-up and corrosion, one must take into account the characteristics of the water used in
the heating circuit.
The normal characteristics of the heating must be such that :
- the THF (calcium carbonate or fur-content of the water) is less than 25° THF (2,5 mol/m³)
- the resistivity is over 2,000 Ohm/cm.
Should the THF-value be over 25° THF, a softening treatment for the water of the heating circuit is necessary.
If the pH is lower than 7.2 and the resistivity is below 2,000 Ohm/cm and the THF-value is below 25° THF (either natu-
rally or after so ftening), a treatment enabling these values to obtain or a treatment forming a film on the insides of the
heating installation should be used.
Furring-up and corrosion water side
In order to avoid all furring-up and corrosion water side, one must take into account the characteristics of the water used.
The installation will be designed in way that the fillings and additions of water be limited as possible and always controlable
(water meter recommended). Any system not controlled of automatic water filling is prohibited
. In all cases, a control of the
addition of water must be envisaged. The expansion vessels overflows must be perfectly visible.
If the conditions here above are not met, the frequent filling of the installation may involve deposits (scale d eposits,
mud, ...) in the boiler and compromise its life d uration.
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