Gas Valve - Immergas VICTRIX Zeus 20 Manual

Technical Documentation
Air-gas circuit.
The circuit consists of a total pre-mix combustion system
comprising a fan (5), a pneumatic type gas valve (7), a Venturi
pipe (3) and a special cylindrical burner (8) that works inside
the condensation module.
Operation.
The fan (5) is controlled by the modulating control board that
varies speed according to the required output.
Thanks to the fan, combustion air is taken from outside the
sealed chamber and sent through a duct where a Venturi pipe
(3) is installed.
A positive pressure signal (P1) is located at the Venturi (3)
inlet which can be varied in a way directly proportional to the
quantity of air extracted by the fan (5) and which is detected
by means of a pressure point connected to the pneumatic gas
valve (7).
The electrical supply of the main valve coils causes both internal
shutters to open and the gas to flow through, whose outlet
pressure is regulated by the same pneumatic valve with a 1:1
ratio at pressure "P1".
Through nozzle (4), the gas is injected at the inlet of the Venturi
pipe (3) where pre-mixing begins with the combustion air.
The resulting mix is ignited on the cylindrical burner surface
(8) by a spark from the ignition electrodes (9).
STVZ ed 02/06
Technical Documentation

Gas valve.

The gas valve features two main coils controlled by the electric
circuit and a pneumatic control unit that modulates the exit-
ing gas pressure at a 1:1 ratio at pressure (P1) detected at the
Venturi pipe inlet.
The ratio between air and gas pressures (off-set) are set on this
valve (see gas regulation).
Electrical coils (4).
Two ON-OFF type coils, powered (230 Vac) by the ignition
unit when the burner has to be ignited.
They are connected in series and energised by mains voltage rec-
tified by means of a diode bridge inside the connector (3).
Pneumatic unit (2).
With this unit the outlet pressure can be varied at a 1:1 ratio
at pressure (P1) detected at the Venturi pipe inlet which is
restored to the valve through a silicone pipe (1).
Thanks to this system, the percentages in the air-gas mix remain
constant at optimum values on the entire modulation field thus
ensuring an almost constant combustion performance.
By loosening the cap, the off-set setscrew can be accessed (2)
by means of which the air-gas ratio can be set.
This is only necessary if, after having analysed the fumes,
incorrect combustion values are found (see air-gas ratio ad-
justment).
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VICTRIX Zeus