Lochinvar 400 - 801 service manual Anti-cycling, Flame Fail Ign

Service Manual

3Troubleshooting

Table 3-4(continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface

FAULT	DESCRIPTION	CORRECTIVE ACTION
	The main control board has received a call	• The control board will release the call for heat after a
Anti-cycling	for heat too quickly after the previous call for	set time period.
	heat has ended.
		• The control board will release the call for heat if the
		outlet temperature drops too quickly.
	The unit has failed to prove main burner	• Inspect spark electrode and associated wiring for
	ignition after four (4) attempts.	damage and connection. Reference page 31 of this
		manual for removal and cleaning procedures.
		Replace if necessary.
		• Check for proper electrical grounding of the unit.
		• Check incoming supply gas pressure. Natural gas
		pressures should be between 4 - 14 inches w.c. and
		LP gas pressures should be between 8 - 14 inches w.c.
		Refer to Section 7 - Gas Connections of the Knight
		XL Installation and Operation Manual for detailed
		information concerning the gas supply.
		• Verify that the plastic hose from the gas valve to the air
		inlet is connected and is not damaged.
		• Verify that the vent/air intake pipes are correctly
		installed and that there are no obstructions.
		• Check for 24 vac to the gas valve at the 2-pin
Flame Fail Ign		connection on the side of the main control board during
		the ignition attempt. If no voltage is present, replace
(will require a manual		the main control board.
reset once the condition		• If 24 vac is present at the main control board, check
has been corrected.
		the wiring between the main control board and the gas
Press the RESET button
		valve. Replace the wiring if necessary. Do not
on the SMART SYSTEM
		disconnect the wiring from the gas valve and attempt to
display to reset.)
		measure voltage at that point. The main control board
		can detect if the gas valve is not connected and will
		display the Gas Valve or Gas Valve Fail fault.
		• If 24 vac is present, check the outlet of the valve to
		ensure the valve is flowing gas. With a manometer
		connected to the outlet tap of the gas valve, when the
		unit is in the prepurge period, there should be a
		negative pressure present. When the valve is
		energized a change in pressure should occur. If the
		pressure change does not occur, the gas valve is not
		opening. Replace the gas valve.
		• Inspect flame sensor and associated wiring.
		Reference page 31 of this manual for removal and
		cleaning procedures. Replace if necessary.
		• Inspect the burner. Reference page 31 of this manual
		for removal and cleaning procedures. Replace if
		necessary.
		• Replace the main control board.

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