Automatic Firing Cm124-R1; Automatic Firing Connections - Rotex A1 BG Installation And Maintenance Instructions Manual

7 x Gas burner
Control of the burner output
The controller uses the set value of the flow temperature (de-
pending on the set operating parameters) and the values for the
flow and return temperature sensors to calculate the required
burner output. The determined output is transferred to the auto-
matic firing unit by bus signal and to the burner fan as a PWM
signal. The burner fan immediately adjusts the gas fan speed and
as such the combustion air flow. The gas controller controls the
gas volume accordingly.
Gas/air compound control
The gas/air compound control (pneumatic compound) ensures
that the O /CO flow is maintained at a suitable level for each
2 2
output and is set by the adjusting screw for the gas/air mix
(fig. 7-3, item 11) and by the adjusting screw of the gas pressure
controller (fig. 7-3, item 12) if required. The burner immediately
responds to every change in the air flow volume through the
gas/air compound control with a corresponding change in the gas
flow volume.
The gas/air compound control (pneumatic compound) consists of
a Venturi nozzle with a ring-shaped gas inlet and a gas pressure
controller.
A vacuum forms in the centre of the Venturi nozzle depending on
the volume flow of the combustible air. This causes the gas to be
sucked into the centre of the Venturi nozzle, conveyed through
the burner fan to the burner surface and optimally mixed.
The gas valve can be adjusted for supply pressures from 5 to
60 mbar (zero pressure controller).

7.1.1 Automatic firing CM124-R1

The gas automatic firing CM124-R1, controlled by a micropro-
cessor, controls and monitors the firing programme and the
temperature sensors for the flow and return temperature. It
features the following properties:
– Direct communication with the controller via the internal eBus,
via which all the available information (temperature values,
control signals, fault information) is transmitted. This is evalu-
ated by the controller and displayed on the control section.
– Fulfilling all safety-relevant functions for combustion monitor-
ing and for safety temperature limiting.
– Possibility of carrying out certain parameter adaptions via
BurnerChipCard (BCC).
– Stable programme times, independent of the fluctuations in
the mains voltage or ambient temperature.
– Operating safety, even in the event of power failures. The
automatic firing unit switches off in the event of a power failure
without a fault - signal and on again once the normal voltage
has been resumed.
32

7.1.2 Automatic firing connections

The function mode of the automatic firing is described in
section 7.1.1.
Fig. 7-4 Automatic firing CM124-R1
Connector Pin Cable colour
L1 brown
X1 PE green/yellow
N
DI2
L1
X2
PE
DI1
L1 brown
X3 PE green/yellow
N
1 brown
3
X4
2 brown
4
BUS - brown
X5
BUS +
N
X6 PE green/yellow
L brown
- brown
X7 PE green/yellow
+
HALL brown
PWM
X11
GND
-
ION
X10
-
Not assigned
Tab. 7-1 Assignment and colours of the connection cable on the
automatic firing CM124-R1
Function
Mains connection,
switched by boiler con-
troller (connection J10)
blue
n.a.
n.a.
None
n.a.
n.a.
Blower mains connec-
tion
blue
Return flow temperature
sensor
blue
Flow temperature sen-
sor
blue
Communication with
boiler controller
blue
blue
Ignition
Gas valve
black
black
Blower speed
grey
n.a.
black
Ionisation
n.a.
FA ROTEX A1 BGe - 02/2014