60
505692
Section 7 Test Procedures
To reduce the risk of electric shock, fire, explosion, serious injury or death:
• Disconnect electric power to the dryer(s) before servicing.
• Close gas shut-off valve to gas dryer(s) before servicing.
• Never start the dryer(s) with any guards/panels removed.
• Whenever ground wires are removed during servicing, these ground wires must be
reconnected to ensure that the dryer is properly grounded.
W001R1
WARNING
Figure 38
55. BURNER SYSTEM OPERATION
– SILICON CARBIDE IGNITION
(Figure 38)
a. Components
The burner has four basic components: a silicon
carbide (glow bar) igniter, burner tube, flame
sensor, and a two-stage gas valve consisting of
a split-coil valve and a secondary coil valve.
The split-coil valve is opened when the dryer
thermostat calls for heat, while the secondary
valve does not open until the igniter has attained
ignition temperature.
b. Pre-Ignition Circuits
When the dryer thermostat calls for heat,
circuits are completed through the holding coil,
flame sensor, booster coil and igniter. Both
coils must be energized to open the split-coil
valve. Once opened, the holding coil can hold
the valve open without assistance from the
booster coil. The flame sensor triggers the
current to travel around the secondary coil and
through the igniter, causing the igniter to get
hot.
c. Burner Circuit
In approximately 30 seconds, the igniter attains
ignition temperature and ignition is made. The
heat from the burner flame causes the flame
sensor contacts (located on burner housing
beside the igniter) to open. A circuit is then
completed through the secondary valve coil,
opening the valve and allowing gas to flow.
d. Momentary Power Interruption
Upon resumption of power, flame sensor
contacts will still be open, permitting secondary
valve to open. However, with the secondary
coil in the circuit, the booster coil cannot draw
enough current to open the split-coil valve.
When flame sensor contacts do re-close, the
secondary valve will close, and the burner
system will be in the normal pre-ignition
circuit.
e. Flame Failure
In case of flame failure, the flame sensor
contacts will re-close in about 45 seconds. This
will close the secondary valve and the burner
system will be in the normal pre-ignition
circuit.
f. Ignition Failure
If flame is not established as flame sensor
contacts open, secondary valve will remain
open until flame sensor contacts re-close.
Flame sensor will continue to recycle the igniter
and secondary valve (about once per minute)
until ignition is made or dryer is turned off.
SECONDARY
COIL
HOLDING COIL
AND
BOOSTER COIL
(SPLIT COIL VALVE)
4
1
5
2
3
D267SE3B
SENSOR
SECONDARY
COIL
HOLDING
COIL
BOOSTER
COIL
IGNITER
120 VOLT, 60 HERTZ
ELECTRICAL
SUPPLY LINE
D268SE3A
WIRING SCHEMATIC
GAS VALVE FOR SILICON CARBIDE IGNITION
