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14.8.2
O
N BOARD
On the burner controller a basic on-board Human Interface (HMI) is available which consists of a push button and
a 2 color (red/green) LED. These are used to indicate basic status information about the control.
900MN
Control operational
When the control is operational and there are no errors present the LED will show as a constant green color.
Control locked
When the control is locked the LED will show as a constant red color. When the control is locked the control can
be reset by using the push button. When the reset has been accepted the control is reset and the status LED will
return to show the green color
Control blocked
When the control is blocked the LED will alternate between green and red with a 1 second interval. When the
blocking error is solved the LED will return to show only the green color.
Exceptions
In case the communication between the main and watchdog processor cannot be established the LED will not
follow the status from the control. In this situation the watchdog processor will reset in an attempt to restore the
communication. When this occurs the LED will appear as green with short pulses in which the LED is off.
F
14.8.3
LAME DETECTION
When the water heater is firing, and the flame is not detected anymore, the gas valve will be closed, and the con-
trol will perform a post-purge, after which a restart will take place.
The presence of a flame is measured through the flame rod that points into the flame. The flame current is meas-
ured by the control as ionization in micro amps (μA).
When the flame current is above Flamerod_Setpoint + Flamerod_Hysterese (1.0 μA + 0.5 μA) a flame will be pre-
sent. When the flame current is below Flamerod_Setpoint (1.0 μA) the flame will not be present.
F
14.8.4
LAME RECOVERY
When the ionization current is too low, the system responds by increasing the minimal fan speed, in order to
keep the flame present. This is done by increasing the minimal fan speed when the ionization current is too low.
Whenever the ionization current is high enough, the minimal fan speed will be decreased again. When the flame
still disappears the minimal fan speed will be increased for the next burn cycle.
• When the flame current is below Flamerod_Setpoint + Flamerod_Delta (1.0 μA + 0.2 μA) the minimal fan speed
will be increased.
• When the flame current is above Flamerod_Setpoint + Flamerod_Delta + Flamerod_Delta * 2 (1.0 μA + 0.2 μA +
0.4 μA) the minimal fan speed will be decreased.
When the flame still disappears the minimal fan speed will be increased for the next burn cycle.
No. of flame losses
Description
0
Minimal fan speed as set in the system
1
In between minimal and ignition fan
speed
2
Ignition fan speed
When the system successfully completes a burn cycle, the minimal fan speed will be reset to the set minimal fan
speed in the system.
HMI
LED
AND
COLORS
Status LED
Reset button
E93.1804.014
83
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