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Radiance Natural Vent Gas Heater
Troubleshooting / Honeywell #8420 Gas Control System
NOTE: Before troubleshooting the gas control system, be sure the external gas shutoff is in the "ON" position.
WARNING: REMOVE THE GLASS PANEL BEFORE PERFORMING ANY GAS CONTROL SERVICE WORK.
SYMPTOM
1. Spark ignitor will
not light
2. Pilot will not stay lit
after carefully
following the
lighting instructions
3. Pilot lights, no gas
to burner, valve
knob ON, remote
switch (rocker
switch) ON
4. Frequent pilot
outage
18
18
POSSIBLE CAUSES
A. Defective or misaligned
electrode at the pilot
B. Defective ignitor (push
button)
A. Defective pilot generator
(thermocouple)
B. Defective automatic valve
operator
C.Defective safety switch
A. Remote switch or wires
defective
B. Thermopile may not gen-
ate sufficient voltage
C. Plugged burner orifice
D. Defective automatic valve
operator
A. Pilot flame may be too low
or high, (blowing or lifting).
causing the pilot to drop out
B. Possible blockage of the
vent terminal
CORRECTIVE ACTION
Using a match, light [ilot. If pilot lights, turn off pilot and
push the ignitor button again. If pilot will not light, check
gap at electrode and pilot - it should be 1/8" to have a
strong spark.
Push piezo ignitor button. Check for spark at electrode
and pilot. If there is no spark at the pilot, and electrode
wire is properly connected, replace ignitor.
Check pilot flame. It must impinge on the thermocouple
or thermopile. NOTE: This pilot burner assembly uses
both a thermocouple adn a thermopile. The thermo-
couple operates the pilot flame. Tighten the thermo-
couple. The thermopile operates the main valve. (ON
and OFF) Clean and/or adjust pilot for maximum flame
impingement on thermocouple and thermopile.
Turn valve knob to "Pilot". Maintain flow to pilot; millivolt
mete 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 the continuity accross the safety limit switch with
the unit cold. If there is no continuity, the safety switch
needs to be replaced.
Check rocker switch and wires for proper connection
Use jumper wires across terminals at rocker switch. If
burner lights, replace rocker switch. If okay, use jumper
wires across rocker switch wires at the valve. If burner
lights, wires are faulty or connections are bad.
1. Be sure wire connecitons from thermopile at gas
valve terminals are tight and thermopile is fully inserted
into pilot bracket.
2. One of the rocker switch wires may be grounded
Remove rocker switch wire form valve termianls. If
burner now stays lit, trace rocker switch wiring from
ground. It may be grounded to the appliance of the
gas supply line.
3. Check the thermopile with a millivolt meter. Take
reading at thermopile ("TP" and "TP/TH") terminals of
gas valve. Should read 325 millivolts minimum while
holding valve knob depressed in PILOT position and
with rocker switch OFF. Replace faulty thermopile if
reading is below specified minimum.
Check burner orifices for debris, and remove.
Turn knob to ON, place rocker switch to ON. Millivolt
meter should read greater than 10mV. If the reading is
okay and the burner does not light, replace the valve.
Clean and/or adjust pilot flame for maximum flame
impingement on thermocouple and thermopile.
Check the vent termianl for blockage.
20004409
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