A.O. Smith DB/DW-720-1810 User Manual page 38

Correct the situation by consulting
the installation or user's manual
on how to adjust pilot flame.
Replace
ignition NO
module. Is voltage (24 Vac) across
terminals MV and MV/PV?
Attach
wires NO Are the wires securely attached to the main
firmly. valve operator on the gas control and to
terminals MV and MV/PV on ignition module?
Replace main gas valve.
Replace cable and/or
ground wire.
Replace pilot burner.
Clean rod or replace
pilot burner if necessary.
PILOT BURNER LIGHTS BUT MAIN BURNER DOES NOT LIGHT
YES
YES
NO
Does the pilot flame cover 3/8° to 1/2"
(10 mm to 12 mm) of igniter/sensor rod?
NO
Does spark stay on for more than 30 seconds
after the pilot is "proven" (lit)?
Ensure the ground wire and igntion cable are
separate from each other (prevents shorting
out).
NO
Are they in good condition (not brittle,
burnt or cracked?
NO Is the ceramic insulater surrounding the
igniter/sensor rod in good condition (not
broken or cracked)?
NO Is the igniter/sensor rod in good condition
(not worn, corroded, sooted or damaged)?
Replace ignition module.
38
YES
YES
YES
YES
YES