LAARS Heating Systems
Page 108
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 main power. Place the unit in
operation following the instructions in SECTION 10.
Once the boiler is operating, check for leaks again and
confirm all fasteners are tight.
Check the setup for the unit according to the
instructions in SECTION 13
11.B.3 Controller
Each unit has an integrated controller 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 troubleshooting
practices before replacing a control.
If it is necessary to replace a controller, turn off all
power to the unit and shut off all manual gas valves to
the unit. Open the front doors to the unit. 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, undo the mounting
screws. To replace the control repeat the steps listed
above in the reverse order making sure to connect all
wires in the proper locations. Place the unit in operation
following the steps outlined in SECTION 10.
11.B.4 Spark Ignition Electrodes
The spark ignition electrode is a dual rod assembly.
The ground rod is fastened to the mounting bracket
of the spark electrode assembly. The spark electrode
passes through a ceramic insulator and then aligns
with the ground rod. In order for a proper spark to form,
the mounting bracket must be grounded to the boiler
chassis. To remove the spark ignition electrodes, shut
off the power to the unit, turn off the main gas supply
and open the front door of the boiler to gain access to
the top portion of the unit. Remove the high tension
ignition wire from the spark electrode. Remove the
two (2) nuts and spacers holding the spark electrode
assembly in place. Pull the spark ignition electrodes out
of the boiler slowly making sure to move the assembly
as needed, so the electrodes are not bent as they are
being removed. If the old assembly is determined to be
defective, install a new spark assembly in the reverse
order, replacing the gasket if necessary.
11.B.5 Flame Sensor
The flame sensor is a single rod system. The minimum
flame signal that will allow the unit to fire is 0.8 volts. To
replace the flame sensor electrode, shut off the power
supply to the boiler. Turn off all manual gas valves
connecting the boiler to the main gas supply line. Open
the front doors of the boiler to gain access to the flame
sensor electrode. Remove the flame sensor wire from
the electrode. Remove the two (2) nuts fastening the
electrode to the burner plate. Remove and replace the old
flame sensor gasket. If the old electrode is determined to
be defective, reinstall a new flame
sensor electrode in the reverse order.
CAUTION
The igniters and sensors can become very hot. If
you touch these parts accidentally, this can cause
burns or injury.
11.B.6 Blower Model 1600
The combustion air blower is a high pressure centrifugal
blower with a variable speed motor. The blower is driven by
the control system using a pulse width modulation (PWM)
signal.
If it is necessary to service, remove, or replace the blower,
the main power MUST be disconnected and the main gas
supply to the unit must be turned off. Open the doors and
remove the doors from their hinges. Remove the top and
top side jacket panels. Remove the fasteners holding the
fuel/air mixer to the blower inlet. Remove the hardware
that is connecting the blower outlet to the unit’s adapter
plate. If the blower is determined to be defective, replace
the existing blower with a new one and assemble in the
reverse order. Be sure to install all of the required gaskets
and O-rings between the blower adapter plate and air/fuel
mixer.
11.B.7 Blower Model 2000-4000
The combustion air blower is a high pressure centrifugal
blower with a variable speed motor driven by a factory
installed variable frequencey drive (VFD) located in the
high voltage box. The speed of the motor is determined
by the controls logic which is delivered to the VFD by a
0-10VDC signal.
If it is necessary to service, remove, or replace the blower,
the main power MUST be disconnected and the main gas
supply to the unit must be turned off. To replace or remove
the blower, turn off main power, remove hardware that
connects the Fuel/Air mixer to the blower, then remove
the hardware that connects the blower to the adapter
plate. If the fan is determined to be defective, replace
the existing fan with a new one by reversing the steps
listed above. Be sure to install all the required gaskets
and O-rings between blower, adapter plate, and fuel/air
mixer.
