Silicon Carbide (Glow-Coil) Ignition - Viking VGR30 Service Manual

BAKE AND BROIL IGNITERS
The bake and broil igniters are mounted to the bake and
broil burner and ignite the gas flowing into the burner.
During a bake or broil operation, current flows through
the ignite, gas valve and thermostat to neutral. As the
ignite starts heating and glowing, its internal resistance
decreases allowing more current to flow through the
bake or broil circuit. When the circuit current reaches
approximately 3.2 to 3.6 amps, the bi-metal arm in the
gas valve flexes, opening the valve, allowing gas to
flow to the burner when it is ignited by the glowing
ignite. The ignite will glow anytime the bake or broil
burners are in operation and cycle on and off with the
thermostat cycling contacts.
The ignite can be checked for continuity by using an
ohmmeter set to the Rx10 range. Remove the ignite
from the burner and disconnect the ignite wiring.
Attach one meter lead to each ignite wire. A resistance
of several hundred ohms may be indicated and may
vary with each ignite. The main purpose of this test is
to see if the ignite is open internally. The ignite may
still be defective even though continuity is indicated
and it glows when the oven is set for a bake, broil or
clean function. A more exact test is to measure the
ignite current with the oven operating. An ammeter
should be inserted in series with one lead of the ignite
or any amprobe attached to the of the ignite will check
the amount of current flowing through the ignite circuit.
With the oven turned on and the ignite glowing red,
a current reading of approximately 3.2 to 3.6 amps
should be indicated.
SILICON CARBIDE (GLO-COIL) IGNITION
21
GAS VALVE
The bake and broil gas valves supply gas flow to the
bake or broil burners. The valve contain a bi-metal arm
attached to the valve seat and is wound with a small
electric heater coil.
approximately 3.2 to 3.6 amps flows through the bake
or broil circuit the bi-metal arm is heated causing it to
flex or bend, allowing gas to flow to the burner where it
is ignited by the burner ignite. An amperage reading
less than 3.2 will cause the gas valve to partially open,
resulting in a reduced gas flow to the burners.
A continuity test can be made to check the bi-metal arm
heater by using an ohmmeter set to the low ohm range
or a continuity tester. Access to the bake valve can be
made by removing the access panel. The broil gas
valve is located on the right side of the burner box
flueway and the bake valve is located on the left side of
the oven burner box. Power to the oven must be shut
off and the gas valve wiring removed.
Attach the meter or tester leads to the two gas valve
terminals facing the rear of the oven. A low ohms
reading or continuity should be indicated. Repeat the
same test on the two gas valve terminals facing the front
of the oven . If infinite ohms or an open heater coil is
indicated on either set of terminals the complete gas
valve must be replaced.
When a current range of