LAARS NeoTherm LC NTV1700 - Install and Operating Manual - Manual (Page 99)

NeoTherm LC Boilers and Water Heaters Page 95
12.1.2 Flap Valve Status Check
Each boiler includes two burners, and each burner
has a flap valve. See Fig. 123.
If one burner in a boiler is operating, and the other
is not, the flap valve for the burner that is off will
remain closed to prevent air from moving backwards
through the burner that is not operating. Before the
Lead/Lag Master controller will allow the system
to operate, it must be able to determine whether
each of these flap valves is open or closed. If the
controller cannot find a signal from one of the
flap valves, the control system will act to prevent
backflow by energizing the blower of the control
with the bad flap valve. If this cannot be done the
control will not allow the whole system to run. If
the flap valve identifications are not set correctly, the
control system will present a “HOLD 119 – Control
Interaction Fault” on the display. For this reason, it
is important that all of the flap valves be identified
correctly.
12.2 About Lockouts, Holds, and
Alerts
The control system on the NeoTherm LC responds
to three kinds of trouble indications:
• A “lockout” is caused by a serious problem
that might involve a safety issue. Once
the controller enters a lockout, the burners
will shut down, and will not be allowed to
run again until the cause of the problem is
corrected, and you reset the control system.
The controller will also trigger a lockout if you
change a safety-related parameter, but do not
finish the “verification” process. (For more
information on verification, see Section 8.8)
Primary
burner
Primary
controller
Flap
valve
Flap
valve
Secondary
controller
Secondary
burner
Operator
interface
Boiler 1
Fig. 123 - Flap Valve Arrangement
During a lockout condition, the image of the
affected controller on the ‘home’ screen will
appear in red. A bell symbol will appear in the
upper left-hand corner of the control screen.
The system maintains a “history” of the 15
most recent lockouts.
• The system may enter a “hold” for a period
of time before locking out. This allows the
controller to see if the error becomes resolved
prior to the hard lockout. Holds can occur
while the boiler is operating.
• An “alert” indicates that some feature of the
control system’s operation was not correct,
delayed or waiting for a response. This
indicates a change in state of the control
system and doesn’t necessarily mean there
is a problem. For example, Alerts occur as
the fan speed transitions from the pre-purge
RPM to the startup RPM. This indicates that
the control system is waiting for a condition
to be satisfied. No Reset is required to
recover from an alert. The system maintains
a “history” of the 15 most recent alerts.
Sometimes it can be helpful to check this list
as a troubleshooting aid.
12.2.1 Responding to a Lockout, Hold, or
Alert
1. If a problem occurs while the system is
starting up, the system will declare a Hold.
A brief explanation of the cause of the Hold
will appear in an orange bar across the bottom
of the screen. If you tap the orange bar, the
system will present more information about
the Hold.