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3 Troubleshooting (continued)
Service Manual
47
Table 3-6 Troubleshooting Chart - Combustion Levels
POSSIBLE CAUSE CORRECTIVE ACTION
Vent/Air Intake Length
or Obstruction
• Refer to Section 3 - General Venting of the Knight Boiler Installation and Operation Manual
for the proper venting and air intake methods for the Knight boiler.
• Check for obstructions at the vent/air intake terminals.
Gas Supply Pressure
• Refer to Section 7 - Gas Connections of the Knight Boiler Installation and Operation
Manual for the proper gas supply for the Knight boiler.
Dirty/Damaged Burner
• Refer to page 31 of this manual for burner removal and cleaning procedures.
• Replace burner if necessary.
Gas Valve Adjustment
• Refer to this page for the gas valve adjustment procedure.
Gas valve adjustment procedure
If adjustment of the gas valve is deemed necessary, use the
following procedure:
Locate the throttle adjustment screw on the side of the
venturi valve (FIG. 3-2). Using a screwdriver, turn the screw
a 1/4 turn counterclockwise to increase CO
2
levels or a 1/4
turn clockwise to decrease CO
2
levels. After performing
one adjustment on the valve, follow the Combustion
Analysis Procedure on page 46 of this manual to measure the
combustion.
If combustion is still not within the specified range, repeat
the procedure. This procedure SHOULD NOT be performed
more than four (4) times. If after four (4) adjustments and
the combustion is still not within the specified range, revisit
the possible causes in Table 3-6 or replace the gas valve.
Figure 3-2 Gas Valve Adjustment