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Testing Procedures
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Oven with Constant Burning Pilot
Operation
With oven thermostat in OFF position, only the constant
burning pilot is lit as shown in the illustration below.
Constant pilot flame
Temperature responsive element
When the oven thermostat is turned to a desired
temperature, more gas flows to the oven pilot.
This extends the oven pilot flame, commonly referred to
as heater pilot. When extended, the pilot flame heats the
temperature responsive element attached to the gas
safety valve.
Constant pilot flame
Temperature responsive element
Turning the oven thermostat to a desired temperature
also increases the main gas flow to the gas safety valve.
Temperature sensitive bulb
Pilot
Gas valve
capillary tube
Gas safety valve
Thermostat
Gas manifold
When the temperature responsive element reaches
approximately 800°F, the internal liquid pressure causes
the gas safety valve to open. Once the valve is opened,
gas flows through the valve to the oven burner orifice
and to the oven burner where it is ignited by the oven
pilot.
RS2310004 Rev. 1
WARNING
Heater pilot flame
Orifice
To avoid risk of electrical shock, personal injury or death,
disconnect power and gas supply before servicing,
unless testing requires it.
The temperature sensitive bulb positioned in the oven
cavity and terminated in the internal thermostat bellows
senses heat from the oven burner flame. As the oven
temperature rises to the set temperature, the oven
thermostat turns off the heater pilot, which allows the
gas safety valve to close against in coming gas
pressure. As the temperature sensitive bulb cools, the
thermostat turns the heater pilot on , which allows gas to
be provided to the oven burner. This on-off cycling
continues until the thermostat is turned off, except at the
broiling setting.
Oven with Pilot Spark Ignitor
Turning the oven thermostat to a desired temperature
initiates a series of events leading to lighting the oven
burner. When the thermostat is set to a desired
temperature the gas supply to the oven pilot is turned
on, the main supply to the gas safety valve is turned on
and the spark switch is closed on top of the oven
thermostat. Closing the spark switch energizes the
spark module. The module produces a spark 4–6 times
per second from the spark ignitor through the path of
pilot gas to ground.
This spark ignites the gas at the pilot, referred to as the
constant pilot flame and heater pilot flame as shown on
the following diagram.
Oven with spark ignition operates identical to constant
burning pilots, but the standing pilot is spark ignited.
Temperature sensitive bulb
Pilot flame
Spark ignitor
Gas safety valve
Spark switch
Gas manifold
Thermostat
38
Orifice
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