14399627
Descripción
Test por David Brown, actualizado hace más de 1 año
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Creado por David Brown
hace casi 6 años
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Pregunta 1
Pregunta
in a modern gas furnace, the component that separates the combustion gases from the supply air is the __________.
Respuesta
-
gas valve
-
heat exchanger
-
inducer fan
-
plenum box
Pregunta 2
Pregunta
what type of furnace moves warm air through the conditioned space without a fan?
Respuesta
-
gravity
-
horizontal
-
lowboy
-
upflow
Pregunta 3
Pregunta
furnace heat exchangers generally are made of ___________.
Respuesta
-
ceramic
-
copper
-
plastic
-
steel
Pregunta 4
Pregunta
what does AFUE stand for?
Respuesta
-
actual fuel usage efficiency
-
annual fuel utilization efficiency
-
annual furnace usage equivalency
-
approved fuel usage estimate
Pregunta 5
Pregunta
the main purpose of a secondary heat exchanger is to _________.
Respuesta
-
evaporate the flue gases
-
provide a backup containment
-
remove additional heat from the flue gases
-
reverse the primary air flow
Pregunta 6
Pregunta
which gas commonly used as a fuel in gas furnaces is heavier than air?
Respuesta
-
butane
-
isobutene
-
methane
-
propane
Pregunta 7
Pregunta
which grade of fuel oil is commonly used in residential furnaces
Respuesta
-
1
-
2
-
3
-
4
Pregunta 8
Pregunta
how many cubic feet of air are needed to burn 1 ft3 of natural gas
Respuesta
-
6
-
10
-
18
-
24
Pregunta 9
Pregunta
how many cubic feet of air are needed to burn 1 ft3 of propane
Respuesta
-
6
-
10
-
18
-
24
Pregunta 10
Pregunta
what is the approximate heat content of 1 ft3 of natural gas?
Respuesta
-
500 btu
-
800 btu
-
1050 btu
-
2500 btu
Pregunta 11
Pregunta
what is the approximate heat content of 1 ft3 of propane
Respuesta
-
500 btu
-
800 btu
-
1050 btu
-
2500 btu
Pregunta 12
Pregunta
what is the approximate heat content of one gallon of No.2 fuel oil?
Respuesta
-
75,000 to 90,000 btu
-
95,000 to 135,000 btu
-
137,000 to 142,000 btu
-
145,000 to 170,000 btu
Pregunta 13
Pregunta
what is a typical manifold pressure for a natural gas furnace?
Respuesta
-
3.5 in w.c.
-
11 in w.c.
-
2 psi
-
5 psi
Pregunta 14
Pregunta
what is the typical atmospheric manifold pressure for a propane furnace?
Respuesta
-
3.5 in w.c.
-
11 in w.c.
-
2 psi
-
5 psi
Pregunta 15
Pregunta
what type of furnace is commonly installed in a closet with underfloor supply ducts?
Respuesta
-
downflow
-
horizontal
-
lowboy
-
upflow
Pregunta 16
Pregunta
which of the following is required for combustion?
Respuesta
-
fuel
-
heat
-
oxygen
-
all of the above
Pregunta 17
Pregunta
which of the following is not a product of complete combustion?
Respuesta
-
carbon dioxide
-
carbon monoxide
-
heat
-
water
Pregunta 18
Pregunta
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
Respuesta
-
25 ft3
-
50 ft3
-
75 ft3
-
100 ft3
Pregunta 19
Pregunta
combustion air may be added to a confined space by a duct to the outside, sized on an input of 1 in2 per __________.
Respuesta
-
1000 btu
-
2000 btu
-
4000 btu
-
5000 btu
Pregunta 20
Pregunta
what type of burners are commonly used with induced-draft gas furnaces?
Respuesta
-
gun style
-
pot style
-
ribbon
-
inshot
Pregunta 21
Pregunta
what is the typical color of a properly burning gas flame?
Respuesta
-
blue
-
orange
-
red
-
yellow
Pregunta 22
Pregunta
in a gas furnace, primary combustion air is introduced in the ________.
Respuesta
-
burner prior to ignition
-
burner after ignition
-
gas line
-
heat exchanger
Pregunta 23
Pregunta
a "dumbbell" style CO2 tester ___________.
Respuesta
-
contains a test fluid that absorbs CO2
-
measures CO2 in parts per million
-
provides a digital readout
-
requires a power supply
Pregunta 24
Pregunta
useful heat output, expressed as a percentage of the total burner input, is known as the ________ of a gas furnace.
Respuesta
-
combustion efficiency
-
fuel efficiency
-
heat exchanger performance factor
-
heating coerfficient
Pregunta 25
Pregunta
which type of ignition system uses a thermocouple?
Respuesta
-
direct ignition
-
hot surface
-
intermittent ignition
-
standing pilot
Pregunta 26
Pregunta
the blower in a standing pilot furnace is generally started by a(n) __________.
Respuesta
-
differential pressure switch
-
ignition module
-
temperature switch
-
time-delay relay
Pregunta 27
Pregunta
a furnace with an induced draft fan uses a ________. to prove air flow
Respuesta
-
high pressure switch
-
lower pressure switch
-
pressure differential switch
-
sail switch
Pregunta 28
Pregunta
flame rectification proves flame by creating a signal in response to a ________.
Respuesta
-
change in resistance
-
current conducted in one direction through the flame
-
temperature activated switch
-
voltage produced by the flame
Pregunta 29
Pregunta
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
Respuesta
-
balanced point
-
design temperature
-
full-load condition
-
reference point
Pregunta 30
Pregunta
residential load calculations should be completed according to ACCA's
Respuesta
-
manual D
-
Manual J
-
Manual N
-
Manual P
Pregunta 31
Pregunta
when furnaces are installed in attics or crawl spaces, special care must be taken to__________.
Respuesta
-
distribute weight properly
-
insulate the ductwork
-
protect water lines from freezing
-
all of the above
Pregunta 32
Pregunta
which of the following is true of low voltage control wiring.
Respuesta
-
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
Pregunta 33
Pregunta
what is the maximum pressure that can be supplied to most natural gas furnaces?
Respuesta
-
3.5 in W.C.
-
14 in W.C.
-
2 psi
-
5 psi
Pregunta 34
Pregunta
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
Respuesta
-
cutting oil
-
moisture
-
pipe sealant
-
teflon tape
Pregunta 35
Pregunta
what is the minimum diameter for condensate drain pipe
Respuesta
-
1/2 in
-
3/4 in
-
1 in
-
1 1/4 in
Pregunta 36
Pregunta
generally speaking a residential thermostat should be mounted _________.
Respuesta
-
approximately 5 ft off the floor
-
in the kitchen
-
near a supply register
-
on an exterior wall
Pregunta 37
Pregunta
which is the proper terminal for heating on most thermostats
Respuesta
-
C
-
G
-
W
-
Y
-
B
-
H
Pregunta 38
Pregunta
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 ________.
Respuesta
-
deadband
-
droop
-
offset
-
throttling range
Pregunta 39
Pregunta
in order to prevent condensation from forming in the heat exchanger, the cooling coil should always be mounted ________.
Respuesta
-
from behind :-)
-
before the heat exchanger
-
below the heat exchanger
-
downstream from the heat exchanger
-
upstream from the heat exchanger
Pregunta 40
Pregunta
in the summer months, the damper on the bypass humidifier should be _________.
Respuesta
-
fully closed
-
fully open
-
partially open
-
removed
Pregunta 41
Pregunta
which of the following is NOT true of a residential zoned system
Respuesta
-
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
Pregunta 42
Pregunta
a type of equipment that transfers both latent and sensible heat from the exhaust air to the supply air is know as a(n) ________.
Respuesta
-
economizer
-
energy recovery ventilator
-
fresh air intake
-
heat recovery ventilator
Pregunta 43
Pregunta
a standing pilot furnace with an atmospheric burner is an example of a __________ gas appliance
Respuesta
-
category I
-
category II
-
category III
-
category IV
Pregunta 44
Pregunta
a high efficiency condensing furnace is an example of a _________ gas appliance
Respuesta
-
category I
-
category II
-
Category III
-
category IV
Pregunta 45
Pregunta
burning of 1 ft3 of natural gas produces __________ of flue gas
Respuesta
-
1 ft3
-
2 ft3
-
10 ft3
-
11 ft3
Pregunta 46
Pregunta
which of the following affects the venting force in a gravity venting system
Respuesta
-
the height of the chimney
-
the percentage of CO2 in the flue gas
-
the type of fuel used
-
the type of fuel pipe used
Pregunta 47
Pregunta
a fan is used to pull flue gases through the combustion chamber in a(n) _________ vent system.
Respuesta
-
forced draft
-
gravity
-
induced draft
-
natural draft
Pregunta 48
Pregunta
how far above the peak of the roof should the chimney extend
Respuesta
-
1 ft
-
2 ft
-
3 ft
-
4 ft
Pregunta 49
Pregunta
a horizontal flue vent must have an upward slope of at least _________ per foot of length.
Respuesta
-
1/8 in
-
1/4 in
-
1/2 in
-
1 in
Pregunta 50
Pregunta
problems related to a shortage or contamination of combustion air are eliminated in a(n) vent system
Respuesta
-
direct
-
forced draft
-
gravity
-
induced draft
Pregunta 51
Pregunta
when can a masonry chimney be used to vent category IV appliances?
Respuesta
-
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
Pregunta 52
Pregunta
category IV furnaces are commonly vented with what type of material
Respuesta
-
single wall metal
-
double wall class B
-
masonry
-
PVC pine
Pregunta 53
Pregunta
when does a category IV vent pipe require insulation?
Respuesta
-
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.
Pregunta 54
Pregunta
category IV equipment required a condensate drain. a trap must be installed in the drain line to _________.
Respuesta
-
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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