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NATE GAS HEATING EXAM QUESTIONS AND ANSWERS 2024
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NATE GAS HEATING EXAM QUESTIONS AND ANSWERS 2024
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NATE GAS HEATING EXAMSecondary heat exchangers:
A: optional heat exchangers used when necessary
B: constructed so return air passes over the secondary heat exchanger first and
then over the main heat exchanger
C: used to add more heat to the supply air before entering the sheet metal
ducting system
D: now rarely used on the higher efficiency furnaces - ANSWERS-B: constructed
so return air passes over the secondary heat exchanger first and then over the
main heat exchanger
A combination fan-stat and high limit:
A: Are both safety controls
B: Consists of a high temperature safety thermostat built into the wall thermostat
C: Separate switches from a single helical bimetal, one switch controls the indoor
fan, the other acting as safety control
D: All the above are correct - ANSWERS-C: Separate switches from a single helical
bimetal, one switch controls the indoor fan, the other acting as safety control
The three basic categories of ignition systems are:
A: Continuous ignition, intermittent ignition and direct ignition
,B: Continuous ignition, direct ignition and manual ignition
C: Automatic ignition, intermittent ignition and direct ignition
D: Automatic ignition, direct ignition and indirect ignition - ANSWERS-A:
Continuous ignition, intermittent ignition and direct ignition
The intermittent ignition system:
A: Lights the burner directly
B: Uses a thermocouple
C: Lights the pilot only on a call for heat
D: Is the most efficient ignition system - ANSWERS-C: Lights the pilot only on a
call for heat
Direct ignition:
A: Uses a spark or hot surface igniter to light the burner directly
B: Gets its name from the fact that it is immediate, direct or fast acting
C: Lights the pilot only on a call for ignition
D: Is the most efficient ignition system - ANSWERS-A: Uses a spark or hot surface
igniter to light the burner directly
The flame sensor:
, A: Is a thick ceramic rod that senses the heat of the flame and causes the rod to
expand and signal the solid state flame board that a flame is present
B: Is a small-diameter conducting rod that senses when a flame is present
because a current flow moves between the rod and the burner when the flame
creates an electrical path between them
C: Is actually a metal-oxide diode that rectifies alternating current to direct
current for the gas valve
D: Is a device that shuts down the main gas valve if the burner flame gets out of
control and starts burning outside the fire box or combustion chamber -
ANSWERS-B: Is a small-diameter conducting rod that senses when a flame is
present because a current flow moves between the rod and the burner when the
flame creates an electrical path between them
Which of the following is a typical sequence of operation for a high efficiency
condensing furnace?
A: induced draft blower runs for 20 seconds, ignitor heats for 15 seconds, gas
valve opens, burner lights off, flame sensor monitors the flame for the entire
heating cycle until the thermostat is satisfied
B: ignitor heats up for 15 seconds, gas valve opens and induced draft blower
starts, burner lights and then flame sensor takes over monitoring until the
thermostat is satisfied
C: induced draft blower runs for 20 seconds, ignitor heats up for 15 seconds, gas
valve opens, burner lights off and flame sensor monitors flame. Plenum heats up,
blower pulls air over the heat exchanger
D: None of these is correct, as condensing furnaces do not use induced draft
blowers. - ANSWERS-C: induced draft blower runs for 20 seconds, ignitor heats up
for 15 seconds, gas valve opens, burner lights off and flame sensor monitors
flame. Plenum heats up, blower pulls air over the heat exchanger
A yellow burner flame is usually caused by:
A: A weak ignitor
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