Harsco Industrial MACH C1500GG Installation & Owner's Manual page 44

5.5.6
Low Air
If the display panel indicates Locking AIR SWITCH NOT OPEN or Locking AIR SWITCH NOT CLOSED this indicates
improper airflow through the boiler. Check the hoses leading to the air switches. Verify proper blower operation. An
air switch error does not necessarily mean that the air switch is defective.
When AIR SWITCH NOT OPEN is shown on the display, check that the air switch is open when the fan is off. Check
that there is no air flow through the boiler when the fan is off.
When AIR SWITCH NOT CLOSED is shown on the display, check that the air switch is closed when the fan is
running. If the air switch does not close within 5 minutes during purge, the boiler locks out. Check that the burner is
clean ("Cleaning the Burner," Section 5.2) and that there are no obstructions to airflow in the intake or exhaust ducts.
5.5.7
Flame Failure
In the event of a flame failure, the main fuel valves are de-energized and a manual reset lockout occurs. Locking
IGNITION FAILURE or Lockout FLAME FAILURE is shown on the display. The cause of flame failure must be
diagnosed and repaired before the control is reset.
When IGNITION FAILURE is shown on the display, the boiler did not light during a trial for ignition. Check that the
spark, electrode, ignition wire, and gas valve are functioning properly.
When FLAME FAILURE is shown on the display, the boiler lost the flame during run. Check that the combustion is
setup properly, the gas pressure is correct, as well as other combustion parameters.
5.5.8
Flame Error
Locking LATE FLAME
Blocking FALSE FLAME
These errors signify flame error. This may be caused by a failed or leaky gas valve or a flame detector malfunction. If
gas valve leakage is suspected, the unit must be isolated by turning off the main gas supply line. Qualified and
knowledgeable service personnel must be called to evaluate and repair/replace the failed parts.
5.5.9
Stack Problem
BLOCKED_FLUE_indicates that the high exhaust back pressure switch has tripped. This may be caused by a
blocked stack, a blocked air inlet, or a blocked condensate system. When the blockage is removed, the boiler will
automatically restart.
A comprehensive listing of the locking and blocking error codes is provided below.
Page 44
MACH® Gas-Fired Boiler