A.O. Smith DB/DW-720-1810 - Manual (Page 37)

37
SPARK AT PILOT BURNER BUT PILOT WILL NOT LIGHT
Ensure all manual shutoff valves are fully open; All filters are clean;
All gas connections are gas tight; Pilot tubing is not damaged,
obstructed or kinked; and pilot orifice is unclogged. Check for
air in gas line, purge (bleed) line if necessary.
NO
Attach wires firmly. Are the wires securely attached to the pilot operator on the gas
control and to the PV & MV/PV terminals on the ignition module?
YES
Install a pressure gauge in the pilot tubing line between the gas
NO control and the pilot burner assembly. Ensure that the pilot
Replace gas valve. adjustment screw (under cap) is adjusted to a position that will
permit gas to flow.
Is pilot gas flowing during ignition attempt?
YES
Turn on power supply. Turn off power supply.
NO Is ignition cable firmly plugged into pilot assembly and module?
Securely connect cable Is ground wire firmly attached to pilot assembly and GND
and/or ground wire. terminal on module?
YES
Replace cable and/or NO Are ignition cable and ground wire in good condition (not brittle,
ground wire. burnt, or cracked)?
YES
Ensure ground strap is the closest metal to the igniter/sensor
Carefully bend down- rod (electrode) to prevent the spark from shorting out
wards top of ground NO to other metal parts (pilot screen, pilot shield, etc.).
strap to achieve Ignition cable must not touch metal surfaces or current carrying
1/8" spark gap. wires.
Is there a 1/8" gap between ground strap and electrode?
YES
NO
Replace pilot Is the ceramic insulator surrounding the electrode in good
burner. condition (not cracked or broken)?
NO
Replace ignition Is there excessive draft conditions that may cause pilot burner
module. ignition problems?
YES
Correct draft problems in a manner that would ensure adequate
combustion and ventilation air and proper pilot burner performance.