Lennox Hearth VIS35 - Manual (Page 25)

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NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Troubleshooting
NOTE: When troubleshooting the gas control system, be sure the external gas shut off valve, located at the gas sup-
ply inlet is in the “ON” position.
IMPORTANT: Call your gas supplier or plumber for additional help with any gas control problem. Valve system
troubleshooting should only be accomplished by a qualified service technician.
SYMPTOM PROBABLE CAUSE CORRECTIVE ACTION
Thin black coating
(soot) forms on the
viewing glass, logs, or
firebox.
Improper log or ember
placement.
Blocked flue.
Improper air shutter
setting.
See Log Set, & Ember Installation.
Check for obstructions in vent pipe, check for proper restrictor setting. See Flue Restric-
tors.
See Air Shutter Adjustment.
Humming or whistling
coming from fireplace.
Normal operating noise.
Dirt in burner orifice.
See Quiet Operation. The noise may be reduced by slightly turning the flame down. Turning
the flame down will reduce the heat output of the fireplace.
Clean orifice.
A change in flame
appearance or burner
operation.
A change in gas pres-
sure.
Improper ember or log
placement.
Have your gas supplier check for correct gas pressure (7” W.C. natural gas; 11” W.C. LP
gas).
See Log Set, & Ember Installation.
Pilot will not light. No gas supplied to unit.
Air in line.
Defective igniter (no
spark at electrode).
The valve control knob
is not turned to “pilot”
and pushed in.
Turn on gas.
To purge, hold in control knob in pilot position for 1-2 minutes and light.
Check for spark at electrode and pilot, if no spark and electrode wire is properly connected,
replace igniter.
See Lighting Instructions.
Pilot will not stay lit
after carefully following
lighting instructions.
Pilot flame is not sur-
rounding thermocouple.
Thermocouple not
generating sufficient
voltage.
Air in gas supply line.
Check pilot flame adjustment (see Maintenance & Servicing section).
Check the connection between the thermocouple lead and the valve. Turn control knob to
“pilot” and push in and light pilot. While lit, take millivolt reading at lead going into valve’s
CPU. Minimum reading should be 17 millivolts. If less, replace thermocouple.
Purge air in pilot gas line by holding in control knob at “pilot” and sparking igniter. The air
in the line may take up to several minutes to purge.
Main burner will not
burn.
Pilot has gone out.
Rocker switch or
thermostat wires are
defective.
Thermopile may not be
generating sufficient
millivolts.
See Lighting Instructions.
Disconnect rocker switch and thermostat wires at terminals 1 and 3 on valve. Jumper
across from 1 to 3 with pilot lit. If burner comes on either rocker switch or thermostat wir-
ing is not functioning.
Make sure thermopile is fully engulfed by the pilot flame. Check thermopile with millivolt
meter. With pilot lit and the rocker switch and thermostat off, the millivolt reading with the
meter connected to valve terminals 1 and 2 should be after 2 minutes at least 325. If the
thermopile lead connections are good at terminals 1 and 2 and readings are less than 325,
replace faulty thermopile.