Immergas HERCULES Condensing 26 2 E Manual page 28

Technical Documentation
Fan.
Operates upstream from the combustion chamber and is
positioned under the condensation module.
It is controlled by the integrated P.C.B. with a positive square
wave signal with variable ON-OFF (duty-cycle) ratio.
Its speed is adjusted (from about 1100 to about 5100 rpm)
depending on the power requested and is controlled using a
sensor with Hall effect, which detects the number of revs.
The fan withdraws the combustion agent air through a plastic
pipe (1), which contributes to reducing the noise and optimises
burner ignition.
The variation of the air flow rate that is introduced into the
mixing pipe, leads to the change of the pressure signal (P1) at
the inlet of the Venturi pipe and allows the pneumatic valve
to regulate the pressure of the outlet gas.
Venturi.
The Venturi pipe (1) is inserted into a sealed pipe, inside which
the combustion agent air and the gas are mixed.
The air is introduced by the fan in the lower area of the pipe,
while the gas exiting the valve is injected by a nozzle (2) in
correspondence with the Venturi pipe inlet (1).
The passage of air in the pipe creates a depression ("Venturi
effect") which, through the 4 holes (3) present at its base, allow
to "drag" the gas inside and to mix it with the air.
The nozzle (2) has a different diameter depending on whether
natural gas or LPG is used as, working with both gases with
more or less constant pressure, its section establishes the cor-
rect gas flow rate.
There are two pressure points at the ends of the Venturi pipe,
used to detect the inlet (P1) and outlet (P2) signals.
Using two small silicon pipes, these signals are taken respec-
tively to the pneumatic gas valve, which must regulate the gas
pressure and to the negative pressure point (P2) arranged in
the upper part of the sealed chamber.
Burner.
It is a cylindrical burner (5) made up from 2 concentric sheet
steel sections, appropriately perforated and built using special
steel that is particularly resistant to high temperatures and
corrosion.
It is inserted inside the condensation module, in a sealed
combustion chamber closed by a flange (4) onto which the
burner is fixed, which in the meantime guarantees its direct
connection to the air-gas mixing pipe (6).
The premixing, the lack of secondary air and the construction
features of the burner ensure high combustion efficiency and
particularly reduced pollutant emissions (see technical data
depending on the model).
The material's high resistance to temperature, allows to work
with a very low flame at a minimum power of:
STHCkW ed 0409
Technical Documentation
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AIR
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P2
P1
GAS
HERCULES Condensing Export
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