Lennox Hearth CI2500DVF - Manual (Page 15)

NOTE: DIAGRAMS & ILLUSTRATIONS NOT TO SCALE.
15
TROUBLESHOOTING THE MILLIVOLT GAS CONTROL SYSTEM
Note: Before troubleshooting the gas control system, be sure external gas shut off valve (located at gas supply
inlet) is in the “ON” position.
Important: Valve system troubleshooting should only be accomplished by a qualifi ed service technician.
SYMPTOM POSSIBLE CAUSES CORRECTIVE ACTION
1. Spark igniter will not light pilot after
repeated triggering of igniter button.
A. Defective igniter
(no spark at electrode).
Check the gap between the electrode and pilot. It should
be between 1/8” and 3/16." If the gap is out of this
range, adjust the gap or replace the pilot.
B. Defective or misaligned electrode at pilot
(spark at electrode).
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 – It should
be between 1/8” and 3/16." If the gap is out of this
range, adjust the gap or replace the pilot. (Figure 18
on page 9 ).
C. Gas supply pressure errant. Check inlet gas pressure. It should be within the limits
as marked on the rating plate.
D. Pilot orifi ce plugged. Clean or replace pilot orifi ce.
2. Pilot will not stay lit after
carefully following the lighting
instructions.
A. Defective pilot generator
(thermocouple). Check pilot fl ame, it must impinge on thermocouple
(Figure 18 on page 9 ). Clean and/or adjust pilot for
maximum fl ame impingement on thermocouple.
Ensure that the connection between the valve and
thermocouple are tight and secure.
3. Pilot burning, no gas to burner, Valve
knob “ON,” Wall Switch “ON.”
A. Wall switch or wires defective. 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.
B. Thermopile may not be generating suf-
fi cient millivoltage.
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
specifi ed minimum.
C. Plugged burner orifi ce. Check burner orifi ce for stoppage and remove.
4. Frequent pilot/burner outage prob-
lem.
A. Pilot fl ame may be too low or blowing (high)
causing the pilot/valve safety to drop out.
Clean and/or adjust pilot fl ame for maximum fl ame
impingement on thermocouple (Figure 18 on page
9 ).