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Ignitor Circuit Operation
The glo-bar ignitor circuit is made up of the following components: a gas valve with safety and main
valves, ignitor, and a flame detector. The safety valve is actuated by a double coil that comprises a
safety coil (resistance approximately 1,400-ohms) and a booster coil (resistance approximately 580-
ohms). Both coils are needed to open the safety valve. Once energized, the safety coil alone will hold
the valve open. The main valve has a single coil (resistance approximately 1,300-ohms).
The flame detector (less than 1-ohm) is mounted on the combustion chamber. It is in the
normally
c
losed position (N.C.). The flame detector is opened by the radiant heat produced by the glo-bar and
once open, the flame detector will be held open by the radiant heat produced by the gas flame.
When the control system calls for heat, the following circuits are energized:
1. L1 power is sent from the timer, through the outlet control and safety thermostats, to the gas valve.
2. The neutral circuit is from the dryer harness through the door switch and motor switch M2 to M1 to
the gas valve.
When the glo-bar is heating, the booster and safety coils are both energized and will open the safety
valve. The main valve is closed as its coil is bypassed by the normally c
losed (N.C.) flame detector.
When the glo-bar reaches ignition temperature, in approximately 60 seconds or less, the flame detector
is heated and opens, placing the main coil in series with the glo-bar. The main valve opens, allowing
gas to flow into the combustion chamber and ignite. The main coil, now in series with the glo-bar,
causes the glo-bar to cool down. However, the flame detector is held open by the radiant heat from
the gas flames. The booster coil is now also in series with the main coil and is essentially inoperative.
Should a momentary power failure occur, the gas valve will shut off and an attempt to restart will not
occur until the flame detector cools and resets, in approximately 30 seconds.
IGNITOR
(GLOWING RED)
DETECTOR
MAIN
SAFETY
BOOSTER
L1
N
Ignitor On
IGNITOR
(NOT GLOWING)
DETECTOR
MAIN
SAFETY
BOOSTER
L1
N
Gas Valve Open