Atwood 79 Series Service Manual page 35

Terminology
Loud Ignition A condition where the air to gas
mixture is off and the burner lights
with a loud noise.
Main Burner Orifice The Orifice regulating the amount of
gas delivered to the Burner.
Manifold The tube delivering gas from the Gas
Valve to the Main Burner Orifice.
Manual Reset Switch A Limit Switch manually reset after
reaching it's set temperature.
MicroAmps: Amps sent back to the Circuit Board to
establish a flame is present.
Millivolts Voltage created by a Thermocouple or
Thermopile.
Multi-Try Circuit Board providing 2 or 3 trials
Circuit Board for ignition.
OEM A manufacture of recreational vehicle,
"Original Equipment Manufacture".
Pig Tail (see Field Electrical Hook Up)
Pilot Light Assembly An assembly used to light the burner.
Plenum The metal box enclosing the
Combustion Chamber directing the
heated air to the duct outlets.
Power Supply A source of electrical power, usually a
converter, inverter or battery.
Primary Air A portion of the combustion air mixing
directly in the Burner at the Main
Burner Orifice.
Resonating A whining noise created by a Burner
with an improper air to gas mixture.
Return Air Air pulled into the furnace, heated,
force through duct outlets back to the
living area.
Safety Lockout Circuit Board not sensing a flame,
cutting power to the Gas Valve.
Sail Switch Air prover switch that will engage
when the Blower Motor reaches 75%
of the rated RPM.
Secondary Air Combustion Air that helps complete
the combustion after the Burner is on.
Sensor Wire Wire carrying an electrical signal from
the Electrode back to the Circuit Board
on a remote sense system.
Slope Gauge (see Incline Manometer)
Definition Terminology
Sooting A black powder that builds up around
the Burner in the Combustion
Chamber normally caused by an
improper air to gas mixture.
Start Capacitor A device giving an electrical boost to
start an A/C motor.
Static Pressure Amount of pressure inside the Furnace
Plenum or Duct caused by the ability
to dispel air out the duct outlets.
Thermocouple Safety device used to generate an
electrical signal sent to the Gas Valve
to hold the Pilot Flame on.
Thermopile Safety device much like a
Thermocouple. It gives a much higher
electrical output, also used to open the
Main Valve with a Thermostat.
Thermostat Device used with the Furnace to
regulate the room air temperature.
Time Delay Relay A normally open Relay. When
activated closes, sending power to the
Blower Motor. When deactivated
allows Blower to run for a period of
time to cool the Combustion Chamber.
Transformer Device reducing 120 VAC to 24 VAC.
U-Tube Tool measuring gas pressure in inches
of water.
VOM Meter reading voltages and OHMs
resistance.
Valve Coil Electromagnetic Coil on the Gas Valve
holding and releasing a plunger to
start and stop the flow of gas.
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Definition