Lennox Hearth EBVSTNM-B User Manual
Page 29
29
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
TROUBLESHOOTING THE ELECTRONIC IGNITION SYSTEM (CONTINUED)
START
CHECK
• Turn Off Gas Supply.
• Ensure Valve Switch Is In ON Position.
• Disconnect Control Harness.
• Check for proper volt-
age at control harness
(see insert A). Voltage
should be 24V between
pressure switch and 24V
common and 24V hot.
NO
• Line voltage power
• Low voltage transformer
• Limit controller
• Wiring
YES
• Plug control harness into valve.
Wait for internal check delay.
• Igniter warms up and glows red. NO
• With pilot burner cable con-
nected, measure voltage at
valve HSI element output. 24V
nominal. (See insert B)
NO
• Replace valve.
YES
YES
• Replace igniter/flame rod
assembly.
YES
• Turn on gas supply.
• Pilot burner lights.
NO
• Check that pilot gas is flowing. Wait
to ensure pilot gas tubing is purged. NO
• Replace valve.
YES
YES
• Measure voltage between 24V hot and
24V common leads to valve control.
Must measure at least 19.5 VAC with
igniter powered (see insert A). To
identify proper lead, this check must
be done with the valve control con-
nected and igniter powered.
NO
• Check transformer and
line volt supply.
YES
• Replace Pilot Assembly.
• Main valve opens and main
burner lights.
NO
• Check that pilot flame makes good
contact with pilot burner flame rod.
• Check for good electrical connection
through the pilot tubing.
• If both of the above are good, replace
igniter/flame rod assembly.
YES
YES
• System Is okay.
• Cycle on/off switch off and back on.
Igniter will cycle off and back
on once during the 90 second
ignition trial. All voltage
measurements must be taken
while the igniter is powered.
When measuring voltage
at connections, use care
to ensure terminals are
not damaged.
• Main burner lights.
NO
• Replace valve.
Insert A
End View of Control Harness Connector
24 Volt
Common
24 Volt Hot
24 Volt
Switched
Check For Damaged or Missing
Terminals in Connector
Insert B
Igniter Terminals
1
2
2
1
2
1