Alarko ACK2, Operation Manual

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Safeguard against lack of water: Sealed (closed expansion tank systems)
shall be equipped with a water level limiter or other device, e.g. minimum pressure
limiter or flow controller, thus providing interlock protection against excess
temperature rise on the heat emitting surface of the boiler.
Expansion vessels: When the heating system’s heat carrying medium water is
heated it expands and it cause pressure rise in sealed systems so expansion
vessels shall be designed to accommodate at least the maximum expansion
volume of the heating water of the system including a minimal water reserve
volume. The expansion vessel shall confirm to prEN 13831. For guidance on
dimensioning refer to EN 12828 but the expansion vessel manufacturer’s installation
instructions shall be paramount.
The expansion vessel and the connection pipe to the heating system shall be
dimensioned so that the temperature rise up to the maximum operating temperature
does not cause a pressure rise in the system at which the pressure limiting
device and safety valves respond and shall be installed in frost protected rooms
or protected against freezing. Diaphragm-type expansion vessels shall be
positioned to the return pipe of the boiler and shall be no shut-off device positioned
between the expansion vessel and the boiler. Consideration may be given to an
engineer’s lockable isolating valve for maintenance purposes.
Operational requirements of sealed systems: In order to maintain a safe and
economical operation, open vented heating systems shall be equipped with:
Temperature measuring device (20 % higher then the operating temperature and
mounted in the flow pipe of the system)
Pressure gauge (50 % higher then the operating pressure and mounted in the
flow pipe of the system
Devices for controlling the operation temperature to adapt the heat supply to the
heat demand. The maximum set-point of the temperature controller shall not
exceed the maximum operating temperature of the boiler.
Pressure maintaining control device to ensure the required minimum operating
pressure of the system. This can be achieved for example by an automatic refill-
set or expansion vessel linked to a low pressure limiter.
Heating system shall be equipped with devices to fill the system and provide
adjustment of the water level. Connections to a drinking water supply system
shall comply with prEN 806-2, e.g. back flow prevention.An adequate supply of
combustion air is important for safe and clean combustion. For open flue heating
systems with a total rated output higher than
50 kW, the rule regarding the supply of combustion air is treated as satisfied, if
the cross-section of the aperture leading into the open air is at least 150 cm2 and
is 2 cm2 larger for each kW of rated output above 50 kW.