Troubleshooting Guide - Millivolt - Lennox Hearth Products Montebello LSM40MN-2 Care And Operation Instructions Manual

TROUBLESHOOTING GUIDE - MILLIVOLT GAS CONTROL SYSTEM
Note: Before troubleshooting the gas control system, Ensure external gas shut off valve, located at gas supply inlet, (and wall switch, iff applicable), is
in the "ON" position.
Important: Valve system troubleshooting should only be accomplished by a qualified service technician.
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1. Spark igniter will not light pilot after
repeated triggering of igniter button.
WARNING: if the pilot will not light
after 1 minute of attempting, wait
for at least 5 minutes for gas to
clear before attempting again.
2. Pilot will not stay lit after
carefully following the lighting
instructions.
. Pilot burning, no gas to burner, Valve
knob "ON," and the (standard) burner
OFF/ON switch is "ON." Read impor-
tant note below.
IMPORTANT NOTE: If an optional
*remote switch is used for burner
operation, if the standard burner
OFF/ON switch is still installed on
appliance it must be in the "OFF"
position.
*Optional remote switch kits - wall
switch, wall thermostat or remote
control.
4. Frequent pilot/burner outage prob-
lem.
possiBLe causes
a. Defective igniter
(no spark at electrode).
B. Defective or misaligned electrode at pilot
(spark at electrode).
c. Gas supply pressure errant.
d. Pilot orifice plugged.
a. Defective pilot generator
(thermocouple)
a. Wall switch or wires defective.
B. Thermopile may not be generating suf-
ficient millivolts.
c. Plugged burner orifice.
d. OFF/ON Switch & *Remote Switch are in
the "ON" position resulting in excessive
resistance.
a. Pilot flame may be too low or blowing
(high) causing the pilot/valve safety to drop
out.
correctiVe action
Check for spark at electrode and pilot; if no spark
and electrode wire is properly connected, replace
igniter.
Using a match, light pilot. If pilot lights, turn off pilot
and trigger the igniter button again. If pilot lights, an
improper gas mixture caused the bad lighting and
a longer purge period is recommended. If pilot will
not light – check gap at electrode and pilot – should
be 1/8" to have a strong spark. If gap measures 1/8",
replace pilot (see Figures 8 or 9 on Page 9).
Check inlet gas pressure. It should be within the limits
as marked on the rating plate.
Clean or replace pilot orifice.
Check pilot flame, it must impinge on thermocouple
(see Figures 8 or 9 on Page 9). Clean and/or adjust
pilot for maximum flame impingement on thermo-
couple. Ensure that the connection between the valve
and thermocouple are tight and secure.
Check wall switch and wires for proper connections.
Jumper wire across terminals at wall switch, if burner
comes on, replace defective wall switch. If okay, jumper
wires across wall switch wires at valve, if burner comes
on, wires are faulty or connections are bad.
Check thermopile with millivolt meter. Take reading
at thermopile terminals of gas valve. Should read
325 millivolts minimum with optional wall switch
"OFF." Replace faulty thermopile if reading is below
specified minimum.
Check burner orifice for blockage and remove.
When turning on the burner using a *remote switch,
ensure that the standard OFF/ON switch is in the "OFF"
position. If both switches are in the ON position, it
may result in excessive resistance (& millivolt drain-
age) and the burner may not come on.
Clean and/or adjust pilot flame for maximum flame
impingement on thermocouple (see Figures 8 or 9
on Page 9).
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