Troubleshooting Guide - Millivolt; Troubleshooting The Millivolt Control System - Superior SDVST-N-B Care And Operation Instructions Manual

TROUBLESHOOTING THE MILLIVOLT 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.
SYMPTOM
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.
3. Pilot burning, no gas to burner, Valve
knob "ON," (and *optional remote
switch, if applicable) is "ON." Read
important note below.
IMPORTANT NOTE: If an optional
*remote switch is used for burner
operation, the unit-mounted burner
OFF/ON switch (if installed) must be
in the "OFF" position.
*Optional remote switch kits - wall
switch, wall thermostat or remote
control.
4. Frequent pilot/burner outage prob-
lem.
22
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. *Optional remote switch or wires defective.
B. Thermopile may not be generating suf-
ficient millivolts.
C. Plugged burner orifice.
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 does not measure
1/8", replace pilot (see Figure 11 on Page 14).
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 Figure 11 on Page 14). Clean and/or adjust pilot
for maximum flame impingement on thermocouple.
Ensure that the connection between the valve and
thermocouple are tight and secure.
Check *remote switch and wires for proper connec-
tions. Jumper wire across terminals at switch, if burner
comes on, replace defective switch. If okay, jumper
wires across 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 remote switch
"OFF." Replace faulty thermopile if reading is below
specified minimum.
Check burner orifice for blockage and remove.
Clean and/or adjust pilot flame for maximum flame
impingement on thermocouple (see Figure 11 on
Page 14).