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Troubleshooting the Gas Control System
NOTE: Before trouble shooting the gas control system, be sure external gas shut off is in the "On" position.
Symptoms
1. Spark ignitor will not light A. Defective or misaligned electrode
2. Pilot will not stay lit
after carefully following
lighting instructions
3. Pilot burning, no gas to
main burner
4. Frequent pilot outage
problem
33
SIT NOVA 820 MILLIVOLT VALVE
Possible Causes
at pilot
B. Defective ignitor (Push Button)
A. D e f e c t i v e p i l o t g e n e r a t o r
(thermocouple), remote wall switch
B. Defective automatic valve
A. Wall switch or wires defective
B. Thermopile may not be generating
sufficient millivoltage
C. Plugged burner orifice
D. Defective automatic valve operator Turn valve knob to "On", place wall switch to "On" millivolt
A. Pilot flame may be too low or
blowing (high) causing the pilot
safety to drop out
B. Possible blockage of the vent
terminal
Corrective Action
Using a match, light pilot. If pilot lights, turn off pilot and
push the red button again. If pilot will not light - check gap
at electrode and pilot-should be 1/8" to have a strong spark.
With the control knob in the pilot position, push the control
knob all the way and hold. Check for spark at electrode
and pilot. If no spark to pilot, and electrode wire is properly
connected, replace the battery in the ignitor module and
try again. Refer to Maintenance Section. If the problem still
exists, replace the ignitor module box.
Check pilot flame. Must impinge on thermocouple/
thermopile. NOTE: This pilot burner assembly utilizes both a
thermocouple and a thermopile. The thermocouple operates
the main valve operation (On and Off). Clean and or adjust
pilot for maximum flame impingement on thermopile and
thermocouple.
Turn valve knob to "Pilot". Maintain flow to pilot; millivolt
meter should read greater than 10mV. If the reading is
okay and the pilot does not stay on, replace the gas valve.
NOTE: An interrupter block (not supplied) must be used to
conduct this test.
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.
1. Be sure wire connections form thermopile at gas valve
terminals are tight and thermopile is fully inserted into
pilot bracket.
2. One of the wall switch wires may be grounded. Remove
wall switch wires form valve terminals if pilot now stays
lit, trace wall switch wiring for ground. May be grounded
to fireplace or gas supply.
3. Check thermopile with millivolt meter. Take reading at
thermopile terminals of gas valve. Should read 250-
300 millivolts (minimum 150) while holding valve knob
depressed in pilot position and wall switch "Off". Replace
faulty thermopile if reading is below specified minimum.
Check burner orifices for debris and remove.
meter should read greater than 150mV. If the reading is okay
and the burner does not come on, replace the gas valve.
Clean and/or adjust pilot flame for maximum flame
impingement on thermopile and thermocouple.
Check the vent terminal for blockage (recycling the flue
gases).
20012761
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