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

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.