HVAC/R Gas Heat Module Final Exam Study Guide QUESTION AND ANSWERS 100% CORRECT (26 PGS)
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INIWIC
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INIWIC
HVAC/R Gas Heat Module Final Exam Study Guide QUESTION AND ANSWERS 100% CORRECT (26 PGS) The range between the highest and the lowest room temperature controlled by the thermostat, is defined as........ - correct answer The temperature swing
The two-stage thermostat heating terminal that is ju...
HVAC/R Gas Heat Module Final Exam
Study Guide QUESTION AND ANSWERS
100% CORRECT (26 PGS)
The range between the highest and the lowest room temperature controlled
by the thermostat, is defined as........ - correct answer ✔The temperature
swing
The two-stage thermostat heating terminal that is jumpered to RC is..... -
correct answer ✔Terminal RH
Which of the following is TRUE of the fan switch? - correct answer ✔Modern
fan switches cycle the fan based on time.
What is a draft pressure switch? - correct answer ✔A switch that senses
when the vent is in a draft condition.
What is the purpose of the limit switch? - correct answer ✔It prevents
overheating by interrupting the circuit to the gas valve.
How is the limit wired on a furnace that uses a line voltage limit? - correct
answer ✔The limit is wired in series with the transformer primary.
The main limit shuts the gas valve down when.... - correct answer ✔The heat
exchanger area becomes overheated.
What does a roll-out switch do? - correct answer ✔It shuts off the gas valve if
flames are sensed outside the combustion area.
,What is the purpose of a flame-proving device in a system with a standing
pilot? - correct answer ✔It shuts off the gas flow in case the pilot goes out.
How many volts are sent to a furnace spark igniter? - correct answer
✔10,000 V
What is an intermittent pilot ignition system? - correct answer ✔The gas pilot
is ignited with each call for heat and shuts off at the end of the call.
How does the flame rod sense the flames in a flame rectification circuit? -
correct answer ✔The flame changes the AC voltage to pulsed DC current.
Why should the heating element of a hot-surface igniter NOT be touched
when installing a replacement igniter? - correct answer ✔The igniter will burn
out where you touch it.
The burner assembly and furnace cabinet should be grounded for safety and
because....... - correct answer ✔Most control boards for direct spark ignition
or hot surface igniters will not operate correctly unless the unit is grounded.
Hot-surface igniters typically operate on....... - correct answer ✔120 V
Some furnaces use two automatic shutoffs that are mechanically in series to
provide additional safety. What type of valves are these? - correct answer
✔Redundant Valves
Why do direct spark ignition furnaces and hot-surface ignition furnaces require
redundant gas valves? - correct answer ✔For safety since there is no pilot
safety solenoid.
, What is a redundant gas valve? - correct answer ✔A gas valve with two
valves mechanically in series.
The operation of modern induced-draft equipment is normally controlled
by........ - correct answer ✔An electronic board
When the room-temperature setting is reached, what components are
opened? - correct answer ✔Thermostat and gas valve circuits.
In a traditional gas furnace with a standard combination gas valve, what
controls the gas valve? - correct answer ✔The heating thermostat.
What does the furnace board do on most modern furnaces? - correct answer
✔It controls the ignition, safety, and blower operation
The typical start up sequence for a hot surface ignition system is........ - correct
answer ✔Combustion blower prepurge, igniter energized after a delay, gas
valve energized after a delay, flames sensed, indoor blower energized after
time delay.
The major electrical loads in an induced-draft hot surface ignition furnace
are..... - correct answer ✔Induced-draft blower, indoor fan motor, the gas
valve, the igniter.
Two stage furnaces require..... - correct answer ✔A two-stage gas valve.
Why should the technician check the furnace door safety switch if nothing
operates? - correct answer ✔The door switch is wired into the main power
circuit.
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