Laars NEOTHERM NTH Series, Installation And Operation Instructions Manual

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Page 57
N
EO
T
HERM
Residential Boilers
®
Unit Control
This unit has an integrated control that incorporates
manual reset high limit control, operating temperature
control, modulating control, ignition control, outdoor reset
control, pump control and many other features. If any of
these features are thought to be defective, please consult
the factory for proper trouble shooting practices prior to
replacing the control. If control replacement is required,
turn off all power to the unit and shut off all manual gas
valves to the unit. Remove the front door to the unit and
the plastic bezel and the control panel. Remove all wire
connections from the control board. The control board
connections are keyed to only allow connection in the
proper location, but proper handling techniques should
be used to avoid damage to the wiring or connectors. To
remove the control, push in on the two tabs on the left side
of the board to unlatch the clips from the control panel.
Rotate the control around the fastening points on the right
side of the control to remove the hooks from the control
panel. To replace the control, repeat the steps listed above
in the reverse orders making sure to connect all wires in
the proper locations. Place the unit into operation following
the steps outlined in Section 9.
Ignitor Assembly
The ignitor assembly is a two rod system that consists of
a ground rod and a spark rod (See
Figure 38 ). To remove
the ignitor assembly, shut off the 120 Volt power supply
to the unit. Turn off all manual gas valves connecting the
unit to the main gas supply line. Remove the front door of
the boiler to gain access to the ignitor assembly. Remove
the two wires connected to the assembly. Then remove
the two bolts connecting the ignitor assembly to the
burner door. If the old ignitor assembly is determined to
be defective, install a new ignitor assembly (check that the
spark gap is 3/16”). Replace the gasket if necessary.
Flame Sensor
The flame sensor is a single rod system. To replace the
flame sensor electrode, shut off the 120 Volt power supply
to the boiler. Turn off all manual gas valves connecting the
boiler to the main gas supply line. Remove the front door
of the boiler to gain access to the flame sensor electrode.
Remove the flame sensor wire from the electrode. Remove
the two bolts fastening the electrode to the burner doors.
Remove and replace the old flame sensor gasket. If the old
electrode is determined to be defective, install a new flame
sensor electrode in the reverse order.
CAUTION
The ignitor and sensor may be hot, and can cause
burns or injury.
Transformer with Integral Circuit Breaker
This unit has a 24Vac transformer with integral 4 amp
circuit breaker installed to supply the control voltage
required for the unit. The transformer is sized to provide
power for the unit only, and should not be used to supply
power to additional field devices. If additional loads are
added, or a short occurs during installation, the integral
circuit breaker may trip. If this happens, be sure to reset the
circuit breaker before replacing the transformer.
The transformer is mounted underneath the control panel.
If the transformer must be replaced, turn off the 120Vac
power to the unit. Remove the transformer wires from
the terminal blocks. Remove the fasteners holding the
transformer, then remove the transformer. Replace with a
new transformer in the reverse order.
If the transformer is replaced with a part other than the
OEM transformer, be sure to add circuit protection if it is not
integral to the new transformer.
WARNING
Failure to include proper circuit protection may lead to
premature component failure, fire, injury or death.
Blower
The combustion air blower is a high-pressure centrifugal
blower with a variable speed motor. The speed of the motor
is determined by the control logic. 120 Volt power remains
on to the blower at all times. If the blower must be changed,
turn off the 120 Volt power and gas supply to the unit. Take
the front panel off. Disconnect the 120 Volt and control
signal connections from the blower. Disconnect the bolts
connecting the Venturi to the blower housing. Disconnect
the fan outlet bolts from the burner door blower arm. If the
fan is determined to be defective, replace the existing fan
with a new one, reversing the steps listed above. Be sure
to install all of the required O-rings and gaskets between
the blower arm and the blower and blower face and venturi
flange.
Figure 38. - Ignitor
NOTES:

SPARK IGNITOR 1.
GIANNONI #gm10-35-108-01
1.08
.18
W20131
3.1
3/16”