If popping is consistent during all hours of operation, the most likely cause is an insufficient air sup- ply. Check for “negative pressure” conditions in the kitchen area. If air is flowing into the kitchen area, this indicates that more air is being exhausted than is being replenished, and the burners may be starved for air.
If the rethermalizer’s gas and air supplies are okay, the problem is most likely with one of the elec- trical components. Examine the ignition module and controller for signs of melting/distortion and/or discoloration due to excessive heat
Verify that the ignition wire is tightly connected at both ends and free of obvious signs of damage. Again, if damage is due to excessive heat in the equipment, that problem must also be corrected. Check for proper operation by disconnecting the wire from the ignitor, inserting the tip of a screw driver into the terminal, and holding it near the frame of the unit as the power switch is placed in the on position. A strong blue spark should be generated for at least 4 seconds.
DANGER
Make sure the insulated handle of the screwdriver is held and not the blade. The sparking charge is approximately 25,000 volts.
Examine the ignitor for any signs of cracking. A cracked ignitor must be replaced.
If all other causes have been ruled out, examine the burner tiles for any signs of cracking. If found, the burner must be replaced.
Fluctuating flame intensity is normally caused by either improper or fluctuating incoming gas pres- sure, but may also be the result of variations in the kitchen atmosphere. Verify incoming gas pres- sure in the same way as for popping discussed in the preceding paragraphs. Variations in the kitchen atmosphere are usually caused by air conditioning and/or ventilation units starting and stopping dur- ing the day. As they start and stop, the pressure in the kitchen may change from positive or neutral to negative, or vice versa. They may also cause changes in airflow patterns that may affect flame intensity.
Dark spots on the burner tiles are the result of an improper air/gas mixture. Adjust the combustion air blower to reduce the amount of air in the mixture to correct this problem.
Flames shooting out of the flue are usually an indication of negative pressure in the kitchen. Air is being sucked out of the burner enclosure and the flames are literally following the air. If negative pressure is not the cause, check for high burner manifold gas pressure in accordance with the proce- dures in Chapter 4.
An excessively noisy burner, especially with flames shooting out of the flue, may indicate that the gas pressure is too high, or it may simply be that the gas valve vent tube is blocked. If the incoming gas pressure is correct and the vent tube is unobstructed, the gas valve regulator is probably defec- tive.