DIAGRAM OPERATION MODULATION TWO STAGES
TC
PG
MB
PA
TR
VE
TMF
max.
M
MT
min.
EC
Legend
T11 Air shutter opening time, from 0 to max.
TW Begins with the closure of the thermostatic line
or the PG. The PA must be in the rest position.
This is the waiting and self-test time.
T10 Begins when the motor starts up and with the
pre-purge phase, within which the PA air
pressure switch must give the go-ahead.
Pre-purge time.
T1
T3
Pre-ignition phase, it ends when the gas valve
opens.
Input signals
Output signals
A
Begin start up
B
Flame present
B-C
Operation
C
Control stop
Air shutter closure + post-purge
C-D
TC-PG
Thermostats/Gas pressure switch line
T10
TW
T11
T1
0
T3
T2
T12
T4
Safety time, within which the flame signal must
T2
reach the EC electrode.
T4
Interval between the opening of the gas valve
and the opening of the second stage.
T6
Air shutter closing time and program zero-setting
time.
T12 Time in which the air shutter shifts to the start-up
position.
MB
PA
TR
VE
TMF
EC
MT
Burner motor
Air pressure switch
Ignition transformer
Gas valve
Thermostat modulation flame
Control electrode
Air servo control
52
T6