Troubleshooting guide

PV500-23 04-2005 Section 23
17
POWER VT
®
BOILER
MAINTENANCE (con't)
Burner and Control Maintenance
13.
Remove the flame safeguard control from its
base. Check the connections in control
mounting base; loose connections can cause
nuisance shutdowns.
NOTE: Always secure gas lines and tag "Out of
Service" before servicing burner nozzle or
electrodes.
14. Pull the nozzle assembly to check the flame and
ignition electrodes. This is done by first
disconnecting the gas train by breaking at the
unions. Then remove the nozzle assembly with
the electrodes and pressure plate attached.
Disconnect the electrode wires. Take care not to
damage the insulation on the electrodes.
15. With electrodes exposed, check for the proper
settings as in Figure 23-7 below. Check for any
hairline cracks in the insulators. Should
replacement of burner electrodes be required,
certain procedures must be followed. In all
cases, removal of electrodes is accomplished
by loosening the electrode mounting clamps.
Draw electrodes out of the nozzle assembly
through the holes in the pressure plate.
16. Inspect electrodes for cracked ceramic or loose
retaining studs that hold the wire within the
ceramic. Select the proper pressure plate hole
to place each electrode and insert electrode
through hole, retaining stud end first.
17. Tighten electrode-mounting clamp slightly until
electrode ceramics are seated firmly and
completely in the mounting bracket without gaps
between ceramics and mounting bracket at the
bearing faces.
18. Measure and set electrodes according to Figure
23-7 below. After gaps and setting are
complete, fully tighten the electrode-mounting
clamp. Do not overtighten or ceramic insulation
may crack.
19. Replace nozzle assembly; be sure to connect
the flame and spark rod wires before installing
nozzle assembly fully into blast tube. Check
connections on the ends of the flame and spark
rod wires for good contact. Look for properly
stripped wire ends. Be sure connections are
firmly attached to the flame and ignition rod
ends. Insulating boots can give a false feeling of
proper seating. DO NOT MOVE
ELECTRODES. Be careful not to bump
electrodes. Check fan wheel for free rotation.
20. Reinstall gas nozzle assembly.
PRESSURE PLATE
Set up and Tolerances
Figure 23-7