Combustion Analysis Procedure; Table 3-5 - Flue Products; Table 3-6 - Troubleshooting Chart - Combustion Levels - Lochinvar KNIGHT 400 Service Manual

3
Troubleshooting

Combustion Analysis Procedure

1. Turn the main power off to the boiler by placing the "On/
Off" switch in the OFF position.
2. Remove the flue temperature sensor from the flue pipe
connection. Note: Combustion measurements will be
made at this point.
3. Turn the main power on to the boiler by placing the
"On/Off" switch in the ON position.
4. Place the boiler into the active position by pressing the
RIGHT SELECT [ON] key (see page 7).
5. Locate the pinhole button below the RESET button on
the display board (see page 7). Insert a thin wire (such as
a paper clip) into the hole and press the button once and
hold for 5 seconds to place the boiler into Service Mode.
In Service Mode the boiler will fire at ignition speed and
will then modulate up to full fire.
6. Remove the flue temperature sensor. Insert the probe
from a combustion analyzer into the hole left by the
removal of the flue temperature sensor.
7. Once the boiler has modulated up to full fire, measure
the combustion. The values should be in the range listed
in Table 3-5 above. The CO levels should be less than
150 ppm for a properly installed unit.
If the combustion is not within the specified range,
reference the chart below for possible causes and
corrective actions.
Table 3-6 Troubleshooting Chart - Combustion Levels
POSSIBLE CAUSE
Vent/Air Intake Length
or Obstruction
Gas Supply Pressure
Dirty/Damaged Burner
Gas Valve Adjustment
46
• Refer to Section 3 - General Venting of the Knight XL Installation and Operation Manual
for the proper venting and air intake methods for the Knight XL boiler.
• Check for obstructions at the vent/air intake terminals.
• Refer to Section 7 - Gas Connections of the Knight XL Installation and Operation
Manual for the proper gas supply for the Knight XL boiler.
• Refer to page 31 of this manual for burner removal and cleaning procedures.
• Replace burner if necessary.
• Refer to page 47 of this manual for the gas valve adjustment procedure.
Table 3-5 Flue Products
Natural Gas
CO O
2 2
8.0% - 10% 3.0% - 6.5%
8. Once the combustion analysis is complete, test the safety
shutoff device by turning the manual shutoff valve to the
OFF position and ensuring that the boiler shuts down
and registers an alarm. Open the manual shutoff valve,
reset the control, and return to Service Mode.
9. Turn the main power off to the boiler and replace the flue
temperature sensor into the flue pipe connection.
10. Place the boiler back into normal operation.
You must replace the flue gas temperature
WARNING
sensor to prevent flue gas spillage into
the room. Failure to comply could result
in severe personal injury, death, or
substantial property damage.
CORRECTIVE ACTION
Service Manual
Propane
CO
2
9.0% - 11% 4.1% - 6.9%
O
2