Gas Circuit; Modulating Gas Valve - Immergas EOLO Mini Technical Documentation Manual

Technical documentation Technical documentation

GAS CIRCUIT

The circuit consists of an atmospheric burner and a modulating type valve for gas combustion and
gas flow adjustment respectively.
- OPERATION
When the main coils (3) are energised, both inner valve shutters open, allowing the gas to flow
towards the burner.
The flow rate/outlet pressure is regulated by means of the gas valve stabiliser and the modulation
coil.
By means of the burner nozzles (7), the fuel is injected into the venturi pipes (ramps) inside which
the air-gas mix is obtained that is ignited by the spark from the ignition electrodes (5).

- MODULATING GAS VALVE

The gas valve (Honeywell VK 4105 or SIT 845) features two main coils and a third modulation coil
controlled by the adjustment board.
The maximum and minimum outlet pressure settings can be made on this valve (see gas
adjustments).
Main electrical coils (3)
SIT 845
Two coils of the ON-OFF type energised (230V
AC) by the adjustment board when the burner has to
be ignited.
In the case of the SIT 845 valve, the two coils are
electrically connected in parallel, while in the case
of the Honeywell VK 4105 valve, these are
connected in series and energised by mains power
rectified through a diode jumper inside the
connection connector (2).
Honeywell VK 4105
Modulation coil (1)
This is a low-voltage coil controlled by the
modulation circuit of the adjustment board.
This controls the gas valve stabiliser and permits
changing the outlet pressure in a way proportionate
to the signal that runs through it.
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STEME ed 07/03 EOLO MINI