SP8016-1005
ACCU-STEAM SERVICE MANUAL
PAGE 15
Connect Flame Tester, AccuTemp P/N FT- 003 to your multi-
1.
meter
Set multi-meter to DC mv.
2.
Connect Flame Tester leads, to Igniter Harness Orange (or
3.
yellow) and Green wires.
Verify your reading is above 60 DC mv and the system will
4.
shutdown below 19 DC mv.
9. If the pilot burner is lighting, determine if the sensing signal level is 25mV (1.07uA) or higher
(see the attached millivolt to micro amp chart).
a. If the level is less than 25mV (1.07uA), check for proper gas pressures to the main
regulator and to the pilot regulator. For natural gas, the pressures must be 5" H2O for
the main gas valve and 3.5" H2O for the pilot burner regulator. For propane gas, the
pressures must be 10" H2O for the main gas valve and 8.0" H2O for the pilot burner
regulator.
b. If the gas pressures are good but the sensing signal level is still poor, check the pilot
orifice for obstruction. Clean or replace as necessary.
c. If the gas pressures are good, the pilot orifice is clean, the burner surface is glowing
orange to bright orange but the signal level is still poor, replace the ignitor probe set
and ground plane.
10. Four types of meter readings are possible: 0 millivolts or 0 micro amps; a steady reading of 25
millivolts or 1.07 micro amps or more; a low reading less than 25 millivolts or 1.07 microamps;
or a fluctuating reading that won’t stabilize. The possible causes for each type of reading are:
a. 0 millivolts or micro amps – Look for an open or grounded sensor wire or flame rod,
or a defective ignition module. The wire and rod can be diagnosed with an ohmmeter.
Make the diagnosis of a defective ignition module after all other possibilities have been
exhausted.
b. 25 millivolts or 1.07 micro amps, with a steady reading – The system is
operating within normal parameters.
c. Fluctuating meter reading – Check that the flame sensor probes are properly
located. Also check for drafts that can cause an unstable flame. A dirty orifice can also
cause an unstable flame.
d. Less than 25 millivolts or 1.07 micro amps – Look for a pilot flame that’s not
properly engulfing the flame-sensing rod. A flame sensor probe too close to the tile will
not be in the proper part of the flame, with not enough ionized gas to allow a proper
signal level to be conducted. Conversely, the same thing holds true if the flame sensor
is too high. Also check the ground connection back to the ignition module. Check that
the flame-sensing rod and ground plane are not oxidized. Clean both with a non
aluminum oxide abrasive.
Important! The ignition module should be the last item that is replaced. Ignition modules are
designed and tested to rigorous standards to ensure safe and consistent operation. Therefore, focus
on other less robust components before swapping out the ignition module.
FLAME SENSE MEASUREMENT
USING ThE VOLTAGE METhOD
TESTING
