Laars NeoTherm NTH Installation And Operation Instructions Manual - page 33
NeoTherm Boiler
Page 33
7.2.1 Burner
Check the burner for debris. Remove the blower
arm assembly to access the burner. Remove the 4 bolts
connecting the blower to the arm (
see Figure 26
).
Remove the 5 bolts, which hold the burner arm in place.
Pull burner up and out. Clean burner, if necessary, by
blowing compressed air from the outside of the burner
into the center of the burner, and wipe the inside of the
burner clean with glass cleaner. A dirty burner may be
an indication of improper combustion or dirty
combustion air. Determine the cause, and correct. If
damaged, replace the burner gasket when replacing the
burner.
NOTE:
When installing the burner, make sure the
flange is aligned with the mating surface, as each is
keyed to control fit.
7.2.2 Modulating Gas Valve / Venturi
The modulating gas valve consists of a valve body
that incorporates the ON/OFF gas flow control and a
negative pressure regulator. It provides the air/gas ratio
control in combination with the venturi to the unit. It is
designed to operate with gas supply pressure between 4
and 13 inches w.c.. To remove the gas valve and or
venturi. 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 gas valve and
venturi. Disconnect the four (4) flange bolts connecting
the gas manifold pipe to the gas valve. Remove the
electrical connections to the gas valve. Remove the bolts
connecting the venturi flange to the blower. This allows
the entire gas valve/venturi assembly to be removed as
an assembly to facilitate inspection and cleaning.
After the valve has been removed, reassemble in
reverse order making sure to include all gaskets and O-
rings. Turn on the manual gas valves and check for gas
leaks. Turn on the 120 Volt power. Place the unit in
operation following the instructions in
Section 6.2
.
Once the boiler is operating check for leaks again and
confirm all fasteners are tight.
Check appliance setup according to
Section 6.2
.
7.2.3 Appliance Control
NeoTherm 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
appliance. Shut all manual gas valves to the appliance.
Remove the front door to the appliance and the control
panel plastic bezel. 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 above in
the reverse order making sure to connect all wires in the
proper location. Place the appliance in operation
following the steps outlined in
Section 6.2
.
7.2.4 Ignitor Assembly
The ignitor assembly is a two rod system that
consists of a ground rod and a sense rod. To remove the
ignitor assembly, shut off the 120 Volt power supply to
the appliance. Turn off all manual gas valves connecting
the appliance 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. Remove and
replace the old ignitor assembly gasket. Reinstall a new
ignitor assembly in the reverse order if the old assembly
is determined defective. Replace gasket if necessary.
7.2.5 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. Reinstall a new flame sensor
electrode in the reverse order if the old electrode is
determined defective.
Caution
Igniters and sensors get hot and
can cause burns or injury.
7.2.6 Transformer
Transformer is not capable of supplying control
voltage for external devices such as zone valves, which
must have their own separate power supply. A circuit
breaker is found on the transformer. In case of short
circuit or overload, first reset the breaker which is found
behind the control enclosure. Should a transformer need
replacing, shut off the 120 Volt power. Unplug the
transformer wires, remove the mounting screws and
remove the transformer. Replace transformer in the
reverse order.
7.2.7 Blower
The combustion air blower is a high-pressure
centrifugal blower with a variable speed motor. Speed
of the motor is determined by the control logic. 120
Volts remain on to the blower at all times. If a blower
change is required, 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