Lochinvar Shield SNR150-100 Installation & Service Manual page 67

12
Troubleshooting
Table 12E (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Water Heater
Interface
FAULT
No Flame
The unit was running and lost the flame
Running
signal.
straight times.
(will require a
manual reset once the
condition has been
corrected. Press the
RESET button on the
display to reset.)
(continued)
DESCRIPTION
This condition occurred four (4)
Installation & Service Manual
TM
CORRECTIVE ACTION
• Ensure gas valve switch is ON (Models SNR150-100
and SNA285-125).
• Check wiring harness connection at the gas valve and
at the main control board.
• Inspect spark electrode and associated wiring for
damage and connection. Reference page 60 of this
manual for removal and cleaning procedures.
Replace if necessary.
• Check for proper electrical grounding of 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 6 - Gas Connections 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 installed
correctly and there are no obstructions.
• Check for 24 VAC to the gas valve at the 2-pin
connection on the side of the main control board
during the ignition attempt. If no voltage is present,
replace the main control board.
• If 24 VAC is present at the main control board, check
the wiring between the main control board and the gas
valve. Replace the wiring if necessary.
• 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
Reference page 60 of this manual for removal and
cleaning procedures. Replace if necessary.
• Inspect the burner. Reference page 60 of this manual
for removal and cleaning procedures. Replace if
necessary.
• Replace the main control board.
and associated wiring.
67