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Gas and Oil Heating Exam

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HVAC Quiz on Gas and Oil Heating Exam, created by David Brown on 16/07/2018.
David Brown
Quiz by David Brown, updated more than 1 year ago
David Brown
Created by David Brown over 6 years ago
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Resource summary

Question 1

Question
in a modern gas furnace, the component that separates the combustion gases from the supply air is the __________.
Answer
  • gas valve
  • heat exchanger
  • inducer fan
  • plenum box

Question 2

Question
what type of furnace moves warm air through the conditioned space without a fan?
Answer
  • gravity
  • horizontal
  • lowboy
  • upflow

Question 3

Question
furnace heat exchangers generally are made of ___________.
Answer
  • ceramic
  • copper
  • plastic
  • steel

Question 4

Question
what does AFUE stand for?
Answer
  • actual fuel usage efficiency
  • annual fuel utilization efficiency
  • annual furnace usage equivalency
  • approved fuel usage estimate

Question 5

Question
the main purpose of a secondary heat exchanger is to _________.
Answer
  • evaporate the flue gases
  • provide a backup containment
  • remove additional heat from the flue gases
  • reverse the primary air flow

Question 6

Question
which gas commonly used as a fuel in gas furnaces is heavier than air?
Answer
  • butane
  • isobutene
  • methane
  • propane

Question 7

Question
which grade of fuel oil is commonly used in residential furnaces
Answer
  • 1
  • 2
  • 3
  • 4

Question 8

Question
how many cubic feet of air are needed to burn 1 ft3 of natural gas
Answer
  • 6
  • 10
  • 18
  • 24

Question 9

Question
how many cubic feet of air are needed to burn 1 ft3 of propane
Answer
  • 6
  • 10
  • 18
  • 24

Question 10

Question
what is the approximate heat content of 1 ft3 of natural gas?
Answer
  • 500 btu
  • 800 btu
  • 1050 btu
  • 2500 btu

Question 11

Question
what is the approximate heat content of 1 ft3 of propane
Answer
  • 500 btu
  • 800 btu
  • 1050 btu
  • 2500 btu

Question 12

Question
what is the approximate heat content of one gallon of No.2 fuel oil?
Answer
  • 75,000 to 90,000 btu
  • 95,000 to 135,000 btu
  • 137,000 to 142,000 btu
  • 145,000 to 170,000 btu

Question 13

Question
what is a typical manifold pressure for a natural gas furnace?
Answer
  • 3.5 in w.c.
  • 11 in w.c.
  • 2 psi
  • 5 psi

Question 14

Question
what is the typical atmospheric manifold pressure for a propane furnace?
Answer
  • 3.5 in w.c.
  • 11 in w.c.
  • 2 psi
  • 5 psi

Question 15

Question
what type of furnace is commonly installed in a closet with underfloor supply ducts?
Answer
  • downflow
  • horizontal
  • lowboy
  • upflow

Question 16

Question
which of the following is required for combustion?
Answer
  • fuel
  • heat
  • oxygen
  • all of the above

Question 17

Question
which of the following is not a product of complete combustion?
Answer
  • carbon dioxide
  • carbon monoxide
  • heat
  • water

Question 18

Question
an unconfined space (in terms of furnace installation) is defined as a space with a volume equal to or greater than _______ per 1,000 btu of input rating
Answer
  • 25 ft3
  • 50 ft3
  • 75 ft3
  • 100 ft3

Question 19

Question
combustion air may be added to a confined space by a duct to the outside, sized on an input of 1 in2 per __________.
Answer
  • 1000 btu
  • 2000 btu
  • 4000 btu
  • 5000 btu

Question 20

Question
what type of burners are commonly used with induced-draft gas furnaces?
Answer
  • gun style
  • pot style
  • ribbon
  • inshot

Question 21

Question
what is the typical color of a properly burning gas flame?
Answer
  • blue
  • orange
  • red
  • yellow

Question 22

Question
in a gas furnace, primary combustion air is introduced in the ________.
Answer
  • burner prior to ignition
  • burner after ignition
  • gas line
  • heat exchanger

Question 23

Question
a "dumbbell" style CO2 tester ___________.
Answer
  • contains a test fluid that absorbs CO2
  • measures CO2 in parts per million
  • provides a digital readout
  • requires a power supply

Question 24

Question
useful heat output, expressed as a percentage of the total burner input, is known as the ________ of a gas furnace.
Answer
  • combustion efficiency
  • fuel efficiency
  • heat exchanger performance factor
  • heating coerfficient

Question 25

Question
which type of ignition system uses a thermocouple?
Answer
  • direct ignition
  • hot surface
  • intermittent ignition
  • standing pilot

Question 26

Question
the blower in a standing pilot furnace is generally started by a(n) __________.
Answer
  • differential pressure switch
  • ignition module
  • temperature switch
  • time-delay relay

Question 27

Question
a furnace with an induced draft fan uses a ________. to prove air flow
Answer
  • high pressure switch
  • lower pressure switch
  • pressure differential switch
  • sail switch

Question 28

Question
flame rectification proves flame by creating a signal in response to a ________.
Answer
  • change in resistance
  • current conducted in one direction through the flame
  • temperature activated switch
  • voltage produced by the flame

Question 29

Question
when the output of a furnace matches the heat loss or heat gain of the conditioned space, the system is said to be at its
Answer
  • balanced point
  • design temperature
  • full-load condition
  • reference point

Question 30

Question
residential load calculations should be completed according to ACCA's
Answer
  • manual D
  • Manual J
  • Manual N
  • Manual P

Question 31

Question
when furnaces are installed in attics or crawl spaces, special care must be taken to__________.
Answer
  • distribute weight properly
  • insulate the ductwork
  • protect water lines from freezing
  • all of the above

Question 32

Question
which of the following is true of low voltage control wiring.
Answer
  • it is exempt from NEC requirments
  • it may not be run in the same conduit as line voltage
  • it may not exceed 100ft in length
  • it must be ran in metal conduit

Question 33

Question
what is the maximum pressure that can be supplied to most natural gas furnaces?
Answer
  • 3.5 in W.C.
  • 14 in W.C.
  • 2 psi
  • 5 psi

Question 34

Question
the sensor of an electronic leak detector can be affected by ________. which may cause the instrument to give a false indication of a gas leak
Answer
  • cutting oil
  • moisture
  • pipe sealant
  • teflon tape

Question 35

Question
what is the minimum diameter for condensate drain pipe
Answer
  • 1/2 in
  • 3/4 in
  • 1 in
  • 1 1/4 in

Question 36

Question
generally speaking a residential thermostat should be mounted _________.
Answer
  • approximately 5 ft off the floor
  • in the kitchen
  • near a supply register
  • on an exterior wall

Question 37

Question
which is the proper terminal for heating on most thermostats
Answer
  • C
  • G
  • W
  • Y
  • B
  • H

Question 38

Question
on an auto changeover thermostat, the difference between heating and cooling setpoints (that keeps the equipment cycling back and forth between heating and cooling) is know as the ________.
Answer
  • deadband
  • droop
  • offset
  • throttling range

Question 39

Question
in order to prevent condensation from forming in the heat exchanger, the cooling coil should always be mounted ________.
Answer
  • from behind :-)
  • before the heat exchanger
  • below the heat exchanger
  • downstream from the heat exchanger
  • upstream from the heat exchanger

Question 40

Question
in the summer months, the damper on the bypass humidifier should be _________.
Answer
  • fully closed
  • fully open
  • partially open
  • removed

Question 41

Question
which of the following is NOT true of a residential zoned system
Answer
  • each zone has its own temperature control
  • there can be no more then four zones
  • zoned units may use a by pass damper to pass excess supply air back into return air
  • zoned units may use a dump damper to pass excess supply air to a non-critical area

Question 42

Question
a type of equipment that transfers both latent and sensible heat from the exhaust air to the supply air is know as a(n) ________.
Answer
  • economizer
  • energy recovery ventilator
  • fresh air intake
  • heat recovery ventilator

Question 43

Question
a standing pilot furnace with an atmospheric burner is an example of a __________ gas appliance
Answer
  • category I
  • category II
  • category III
  • category IV

Question 44

Question
a high efficiency condensing furnace is an example of a _________ gas appliance
Answer
  • category I
  • category II
  • Category III
  • category IV

Question 45

Question
burning of 1 ft3 of natural gas produces __________ of flue gas
Answer
  • 1 ft3
  • 2 ft3
  • 10 ft3
  • 11 ft3

Question 46

Question
which of the following affects the venting force in a gravity venting system
Answer
  • the height of the chimney
  • the percentage of CO2 in the flue gas
  • the type of fuel used
  • the type of fuel pipe used

Question 47

Question
a fan is used to pull flue gases through the combustion chamber in a(n) _________ vent system.
Answer
  • forced draft
  • gravity
  • induced draft
  • natural draft

Question 48

Question
how far above the peak of the roof should the chimney extend
Answer
  • 1 ft
  • 2 ft
  • 3 ft
  • 4 ft

Question 49

Question
a horizontal flue vent must have an upward slope of at least _________ per foot of length.
Answer
  • 1/8 in
  • 1/4 in
  • 1/2 in
  • 1 in

Question 50

Question
problems related to a shortage or contamination of combustion air are eliminated in a(n) vent system
Answer
  • direct
  • forced draft
  • gravity
  • induced draft

Question 51

Question
when can a masonry chimney be used to vent category IV appliances?
Answer
  • when it is existing chimney
  • when it is no more that one story tall
  • when it is used as a common vent along with a category I appliance
  • Never

Question 52

Question
category IV furnaces are commonly vented with what type of material
Answer
  • single wall metal
  • double wall class B
  • masonry
  • PVC pine

Question 53

Question
when does a category IV vent pipe require insulation?
Answer
  • always
  • never
  • only when the vent pipe runs outdoors
  • when the length of the vent pipe running through an unconditioned space exceeds the length listed in the manufacturers tables.

Question 54

Question
category IV equipment required a condensate drain. a trap must be installed in the drain line to _________.
Answer
  • break the vacuum allowing water to drain
  • keep water from draining to quickly
  • prevent water from freezing
  • provide a seal that prevents the leakage of flue gas
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