Immergas HERCULES Condensing 26 2 E Manual page 27

Technical Documentation
Air-gas circuit.
The circuit consists of a total premix combustion system com-
posed of a fan (5), a pneumatic gas valve (7), a Venturi pipe
(3) and a special cylindrical burner (8) that operates inside the
condensation module.
Operation.
The fan (5) is controlled by the integrated P.C.B. that varies
its speed depending on the output requested.
Its functioning allows to withdraw combustion agent air from
outside of the sealed chamber and introduce it into a pipe
where a Venturi pipe is inserted (3).
At the inlet to the Venturi (3) there is a positive pressure signal
(P1) variable in a directly proportional manner to the amount
of air taken in by the fan (5) and which is detected by a pressure
point connected to the pneumatic gas valve (7).
The electric power supply of the valve main coils causes both
internal shutters to open and allows the passage of gas, whose
outlet pressure is regulated by the same pneumatic valve in a
1:1 ratio to pressure "P1".
The gas is injected at the entry of the Venturi pipes (3) through
a nozzle (4), where the premix starts with the combustion
agent air.
The mixture obtained in this way is ignited on the surface
of the cylindrical burner (8) by the discharge of the ignition
electrodes (9).
STHCkW ed 04/09
Technical Documentation
Gas valve.
The gas valve is equipped with two main coils controlled by
the electric circuit and with a pneumatic unit that modulates
the outlet gas pressure in 1:1 ratio to the pressure (P1) detected
on the inlet of the Venturi pipe.
The calibration of the ratio between the air and gas pressures
are carried out on the valve (off-set) (see gas regulations).
Electric coils (4).
There are two ON-OFF coils that are powered with direct
current by an integrated P.C.B. when the burner must be
ignited.
They are connected in series and powered through a connec-
tion connector (3).
Pneumatic unit (2).
Allows to vary the outlet pressure in 1:1 ratio with the pressure
(P1) detected at the inlet of the Venturi pipe that is taken back
to the valve using a small silicone pipe (1).
Thanks to this system, the percentages in the air-gas mixture
are maintained constant at optimal values on the entire range
of modulation, thus guaranteeing a more or less constant
combustion efficiency.
The air-gas ratio calibration can be performed using the off-set
adjusting screws.
This is necessary only when, after having performed flue
analysis, incorrect combustion parameter values are detected
(see air-gas ratio regulation).
1
2
3
25
4
HERCULES Condensing Export