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installed the cables should be properly coiled and
secured and reconnected to the LMV.
In the event of failure of the on/off Honeywell solenoid,
the entire valve must be replaced. Replacements
solenoids are not available from Honeywell at this
time. For the pressure regulating valve, the upper half
of the valve may be replaced leaving the valve body in
place. Care must be taken to replaced the fuel and air
side sensing lines connected to the pressure regulator.
When a new regulator is installed, the pressure
adjustment screw should be set to the approximate
position of the replaced unit for initial startup – this can
be done by counting the exposed threads on the old
unit and matching this number on the new unit. The
combustion setup procedure outlined in Section 10.B.2
should then be followed to obtain the proper operating
conditions.
Replacement of the air damper and air/gas mixer can
be achieved by removing the flange bolts at the blower
inlet and the flange bolts between the two components.
Gaskets and/or o-rings at these flange joints must be
carefully re-installed to prevent air leakage into the
system.
After removal and replacement of air/gas train
components, turn on the manual gas valves and check
for gas leaks. Once the boiler is operating, check for
leaks again and confirm all fasteners are tight.
Check the setup for the unit according to Section 10.
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,
FT
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 remove the top rear cover of the boiler to gain
access into 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. Remove
the top rear cover of the boiler to gain access into the
top portion of the unit. 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.
The igniters and sensors can become very hot. If
you touch these parts accidentally, this can cause
burns or injury.
11.B.6 Blower
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 air damper to the blower inlet. Remove the hardware
that is connecting the blower outlet to the unit's air inlet
transition duct. 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 damper.
Only a factory supplied blower should be used as a
replacement. And once a new blower is installed, the
combustion setup should be checked per the procedure in
10.B.2 on page 110
Page 115
CAUTION
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