Gas Circuit; Modulating Gas Valve - Immergas EOLO Eco Series Technical Documentation Manual

Technical Documentation

Gas circuit.

is circuit consists of an atmospheric burner and a modulating
gas valve that permit, respectively, the combustion of gas and
the regulation of its flow rate.
Operation.
When the main coils (3) are energised, both inner valve shutters
open, allowing the gas to flow towards the burner.
e flow rate/outlet pressure is regulated by means of the gas
valve stabiliser and the modulation coil (1).
e burner nozzles (7) inject the fuel into the vertical Venturi
pipes (ramps) inside which an optimum air-gas mix is obtained
which, during combustion, minimises secondary air require-
ments. e spark from the ignition electrodes (8-9) ignites
the burner that, working with a "low" flame on the whole
surface, ensures combustion at temperatures that are lower
than those with traditional burners. is all helps to reduce the
emissions of oxides of nitrogen (NO
(CO) considerably.

Modulating gas valve.

e gas valve (SIT 845) features two main coils (3) and a
modulation coil (1) controlled by the integrated board.
e maximum and minimum outlet pressure settings can be
made on this valve (see gas regulations).
Main electrical coils (3).
ey are two ON-OFF type coils energised (230 Vac) by the
integrated board when the burner has to be ignited.
ey are electrically connected in parallel and energised by
mains power through a special connector (2).
Modulation coil (1).
is low-voltage coil is controlled by the integrated board.
It controls the gas valve stabiliser and is used to change the
outlet pressure in a way proportionate to the dc current that
runs through it.
STEEkW ed 12/03
) and carbon monoxide
x
10
Technical Documentation
Burner (4).
e burner consists of two rows of 12 (24 kW version) and 14
(28 kW version) vertical Venturi pipes (5) inside which gas is
injected by an equal number of nozzles (7) mounted on the
special, aluminium manifold (6). e diameter of the nozzles
(7) varies according to the type of gas utilised (see technical
data). At the top, the return pipe of the primary circuit water
travels across the top of it lengthways, cooling it down when
it is working. is is necessary because the combustion with a
low flame and the reduced quantity of air tend to increase the
burner surface temperature.
A diaphragm plate (11) is fixed to the burner (4) that improves
ignition, optimising the flow of gas and air.
Ignition occurs thanks to an integrated electronic board
that controls both the ignition (8-9) and detection (10)
electrodes.
Ignition electrode (8).
It is controlled by the integrated board that produces an
electric discharge between its end and the earthed electrode
(dummy) (9).
ey are located on the left side of the burner.
Detection electrode (10).
It is controlled by the integrated board and detects burner
ignition.
It is located on the burner side opposite to the ignition elec-
trode.
9
8
11
5
7
4
10
6
EOLO Eco kW