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DESCRIPTION OF OPERATION WITH GAS (METHANE)
The burner command and control (cycle relay) equipment is turned on by means of the switch on the control
panel ( I).
Control box Specifications
GAS TRAIN STRUCTURE AND COMPOSITION
When the thermostats (pressure switches for steam boilers) are closed, the cycle relay equipment carries out the
ignition program, and starts the fan and pump motors to carry out the pre-ventilation phase.
The pressure of the air supplied by the fan must be high enough to activate the relative pressure switch, otherwise the
unit shuts down “cut-out”. During “pre-ventilation” the air lock is switched to the 2
nd
flame position by the air regulating
servomotor (pre-ventilation with air open – see BT 8653/1). Subsequently, the air regulation servomotor moves the air
lock to the set position for the 1
st
flame. It then activates the ignition, followed by opening of the 1st (pilot) flame valve
and the safety flame. The valve for the first flame has a built-in flow regulator that allows the gas delivery for starting
to be regulated. The safety valve is activated and deactivated at the same time as the valve for the first flame. As a
result the flame, detected by the flame detection device (UV photocell) allows the ignition phase to proceed and be
completed when ignition is deactivated. The unit activates the air regulation servomotor, which moves the air lock to
the set position (see BT 8653/1) for the 2
nd
flame. As the air regulation servomotor turns, a special cam closes a
microswitch, that delivers power to the solenoid valve of the 2
nd
flame, which opens gradually. Therefore, it is clear
that if the air regulation servomotor does not open the air lock of the 2
nd
flame, the gas valve of the 2
nd
flame will not
be opened either. If there is no flame, the unit shuts down as a result of a “safety cut-out”.
The valves close immediately in the event of a “safety cut-out”.
Control box or
Safety
Preventilation
Pre-ignition
Post-ignition
Time between opening
programmer
time
time
1
st
flame valve
and 2
nd
flame valve
s
s
s
s
s
LFL 1.333
3
31,5
6
3
12
Cyclic relay
0002910870
0002910880
0002910890
CTV -
Valve tightness control
F
-
Filter
LDU -
LDU valve tightness control
Pct
-
Pressure switch for gas control
Pmax-
Maximum pressure switch
Pmc -
Minimum and control pressure
switch gas leaks
Pmin -
Minimum pressure switch
R
-
Pressure regulator
RF
-
Pressure regulator with filter
RFP -
Pressure regulator with filter
for pilot gas train
RM
-
Manual flow rate regulator
RP
-
Pneumatic regulator
VF
-
Regulator throttle valve
VL
-
Operating valve
VL2 -
Two-stage operating valve
VLP -
Operating pilot valve
VP
-
Pilot valve
VPS -
VPS valve tightness control
VS
-
Safety valve
VSP -
Safety pilot valve
Ø
-
Gas train diameter
Ø1
-
Main gas train diameter
Ø2
-
Pilot gas train diameter