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Level 3 Nexstar Flashcards | StudBud
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Level 3 Nexstar
Level 3 Nexstar
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Questions
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Answers
1
What can be used to minimize movement or vibration in ducts?
D.) Both A and B
C.) Inflexible joints
A.) Flexible joints
B.) Fabric joints
2
The suction line does not need to be insulated.
False
True
3
A direct return bypass is usually sized to handle only about 25 percent of the total system air volume.
True
False
4
When purging a system with nitrogen while brazing, the flow indicator should be adjusted to ____ SCFH.
7
100
3-5
10
5
The line set consists of two refrigerant lines that connect the condensing unit to the evaporator coil.
False
True
6
The amount of air flowing past a point in the duct per unit of time is called air velocity.
True
False
7
Factory built chimneys are commonly used with natural gas, condensing furnaces.
True
False
8
Ideally, vent connectors should be less than _______ feet long.
Eight
Six
Five
Seven
9
Moisture in a sealed system can create which of the following issues?
Presence of non-condensable gases
All of the above
Creation of acid
Oil sludging
10
When performing a nitrogen purge during brazing, the flow rate on the flow indicator should be set to ___ SCFH
7-9
5-7
1-3
3-5
11
Which material is
not required
to install a zone damper?
Silicon caulk
18-gauge or 22-gauge wire
Wire nits
Aluminum duct tape
12
What is anohter name for a ferrule?
Compression Flow Rate
Compression fitting
compression Tee
Compression Ring
13
High temperature brazing without performing a nitrogen purge will result in _________ .
Disortion of the tubing
Cupric oxide scaling
Pinhole leaks
Cold brazing joints
14
A fire extinguisher of the correct type should be nearby for easy access in case any flammable material near the work
True
False
15
Dampers are placed in ducts to control the airflow to certain rooms (or zones) of the home.
False
True
16
Always mount a thermostat above a register.
True
False
17
Air velocity is most often expressed in ______________.
Cubic feet per minute (CFM)
Feet per minute (FPM)
Cubic meters per second (CMS)
Cubic feet per hour (CFH)
18
Which tool is
not required
to install a bypass damper?
Felt-stip marker
Cordless drill
Sheet metal duct cutter
Hammer
19
What type of home would benefit using an evaporative cooler?
Any home in any climate
A home in a very arid, dry climate
A humid climate
Any climate that is hot
20
Which of the tools below is the best to use when cutting the suction line at the evaporator coil?
Hack saw
Rasp file
Tubing cutter
Reaming tool
21
Nitrogen, when used for system purging should be regulated to __________ .
120 - 150 psig
150 - 170 psig
100 - 110 psig
110 - 120 psig
22
What is the liquid line
The section of piping from the evaporator coil to the condenser coil
The section of piping connecting the condenser to the expansion valve
None of the above
The coil within the evaporator
23
A traditional wood stove is designed to heat _______________.
The whole house
Heat a floor
Mutilple floors in a house
A larege room or area
24
What is meant by the term “batch coal-burning stove”?
Coal can be loaded into the stove by either hand or mechanical means
None of the above
A batch of coal is automatically loaded into the stove by mechanical means
Coal needs to be loaded into the stove by hand
25
What type of fitting is used to create a joint with a specialty tool?
Brazed
Compression
Pressed
Soldered
26
During a load calculation using new software, all rooms have to be measured.
False
True
27
During brazing a small amount of nitrogen should be flowing through the piping system because it _____.
Prevents oxidation scaling
prevents restrictions of tubing
Pushes out oxygen
All the above
28
What are the advantages of a wood-burning furnace over a wood-burning stove?
All of the above
It can heat a much larger area than a wood stove
Desgined to hold more and larger pieced of wood
Has a much longer burn time - up to twice that of a wood stove
29
Nitrogen is safe to use for pressure tests and brazing.
False
True
30
The higher the temperature of the vented flue gas, the more efficient the furnace.
False
True
31
What device protects the heating unit and monitors the discharge air temperature of the system?
Static pressure sensor
Outdoor air sensor
Low limit switch or sensor
High limit switch or discharge air temperature sensor
32
What is the reason to maintain flow velocity in air ducts within certain limits?
Prevent exessive noise
Avoid leakages
Prevent unacceptable frition loss
All of the above
33
Why is it important to reinstall the Teflon O-Ring when reinstalling the TXV valve?
Prevent leakage at the suction line and evaporator coil
Prevent leakage at the junction of the TXV and evaporator coil
Prevent leakage at the compressor
Prevent leakage at the TXV and the sensing bulb capillary tube
34
A Nitrogen Flow Indicator is a _____________.
Visual tool that confirms proper brazing
Visual tool that confirms oxygen is present
Visual tool that confirms oxygen is absent
Visual tool that confirms the proper flow rate of nitrogen gas
35
Copper is 100% recyclable and every effort should be made to keep it out of landfills.
False
True
36
What can be used to mount the condensing AC unit?
All of the above
Steel framing
Condensing Pad
Treated Lumber
37
Which of the following gases can be used to pressure test a repaired system?
Oxygen
Nitrogen
Helium
Acetylene
38
Which type of load calculation can be used?
B.) Load Calculation Software
D.) Both A and B
C.) None of the above
A.) Handwritten Manual J
39
9
True
False
40
What is the purpose of the bypass damper?
Prevent flue gases from leaking into the home
None of the above
Maintain steady airflow and static pressure through the system
Ensure that water condensate drains away
41
Condensing furnaces can never be vented with PVC pipe.
False
True
42
The thermostat is considered “the brains” of the entire zoning application.
True
False
43
A radiant system can only be used for heating a home.
True
False
44
When selecting proper equipment size for an air conditioner, the designer will need what information?
A) Total Cooling BTU's
C) Total CFM Required for the system
D) Both A and C
B) Total Heating BTU's
45
Return ducts usually use a design friction loss factor of ____ “ of w.c. Per 100 feet.
.05
.10
.02
.80
46
A block load calculation is what?
A calulation of the hottest part of the home
A calculation of the enire conditioned space of the home
A calculation of each condiontioned room in the home
A calulation of a single condiotioned room in the home
47
Per ASTM standards what should the purity level of copper tubing be?
100
97.7
99.9
98.6
48
A furnace that vents 15 percent of its heat has an AFUE rating of 85%.
False
True
49
The suction line should be run along the floor within the home.
True
False
50
What compressed gas should be used to purge a sealed system?
Carbon Dioxide
Nitrogen
Oxygen
Hellium
51
Duct runs should be as straight as possible.
True
False
52
Oxidiation is the effect of oxygen on another material.
False
True
53
Automatic round dampers range in size from _______________.
5 to 20 inches
None of the above
15 to 30 inches
10 to 15 inches
54
Why do people choose a solid-fuel heat system over conventional heat systems?
Ample fuel supply
Non-electric
Cheaper energy costs
All of the above
55
Which of the following are the advantages of using compression fittings?
Faster than making a flare joint
Can be used with mulitple types of tubing materials
ALL THE ABOVE
Faster to create a joint than using brazing or soldering
56
Part of the prep to remove the EvapCoil is to evacuate & recover any refrigerant charge present in the SealedSystem
True
False
57
If the flow rate is set too high the nitrogen push back can result in _______________.
Pin holes
Cooling of the pipe, which reduces brazing heat efficieny
Joint not sealing properly
All the above
58
The maximum velocity in homes with low and medium pressure loss ducts should not exceed ________ FPM.
100
400
600
1200
59
Which of the following would impact a load calculation when replacing an existing HVAC system?
Adding attic insulation
All of the above
Finishing a basement
New windows or doors
60
What is required for combustion to occur?
Combustion Air
All of the above
Source of Ignition
Fuel
61
When drawing down a vacuum on a sealed system the desired pull-down value is ____.
500 Microns
400 Microns
600 Microns
750 Microns
62
Manual__________is the Industry standard calculating tool for sizing a home’s supply and return ductwork and register’s.
D
R
J
S
63
What are the primary goals when designing a new or replacement HVAC system?
A.) Identify proper capacity and type of equipment needed
D.) None of the above
C.) Both A and B
B.) Determine the correct type and size of ductwork
64
What is another name for the evaporator coil?
A-coil
Condensor coil
E-coil
Duct Coil
65
Software packages are increasingly replacing handheld duct calculators.
False
True
66
Alloys that contain phosphorus, such as BCuP-3-BCuP-5, are self-fluxing when used in clean copper to copper applications
True
False
67
90 % of Anthracite coal used today is from the state of Pennsylvania
True
False
68
When pressure testing a HVAC system __________ is used.
Pressurized R-12 refrigerant
Pressurized Compressed air
Pressurized Helium
Pressurized Nitrogen
69
How do you tell what type of copper pipe is available to you?
Read the etched information on the pipw
Read the stamped information on the pipe
Check the color of the stamped information
All of the above
70
Why should gas appliances never be common vented through a chimney that serves a wood/coal burning device?
The flue gases prevent the wood/coal burning device from operating properly
None of the above
Downdrafts can carry flue gases into the living space
The common venting can make the living space uncomfortably cold
71
What method of joining materials together requires the use of heat?
Annealing
Brazing
Brazing & Soldering
Soldering
72
Copper is 100% recyclable and every effort should be made to keep it out of the landfills
True
False
73
As a rule, the ash from a pellet stove needs to be removed after every __________ hours of operation.
300-500
600-800
200-400
500-700
74
Is sensible heat or latent heat used in a load calculation?
None of the above
Sensible Heat and Latent Heat
Latent Heat Only
Sensible Heat Only
75
What tool is not required when installing an evaporator coil?
Tape Measure
Cordless Drill
L-Square
Hacksaw
76
Beside performing Lockout/Tagout, what other safety steps should be performed?
Use a multimeter or non-contact AC tester to verify main power is off
All of the above
Have a fire extinguisher nearby the area you are working
Turn thermostat(s) to the off position
77
Which furnace type produces the most condensation?
None of the above
Natural drafft
Condensing
Induced draft
78
The suction line and the liquid line can be supported using the same mounting brackets.
False
True
79
Never mount a thermostat in an area that receives direct sunlight.
False
True
80
You do not need a flow regulator to properly flow Nitrogen for brazing
False
True
81
Which tool is not required to complete a lineset installation?
Cordless Drill
Tube Cutter
Circular saw
Oxyacetylene torch
82
4
All of the above
Very high static pressure
A System that consistently freezes up
Compressor Failure
83
Dampers should be installed as close as possible to the main duct or supply air plenum
True
False
84
Type B vents are single wall in construction
False
True
85
Wood burning furnaces are generally controlled by a standard thermostat in the hallway of the main floor living space.
True
False
86
9
False
True
87
Types L and ACR tubing cannot be used for the same applications.
False
True
88
“Sludging” of compressor oil will ____________________________ .
All of the above
Damage the compressor
No longer provide proper lubrcation
Cause the oil to become thicker
89
A type of ductwork that contains an inner liner made of plastic and a wire spiral is called __________________.
Flexible duct
Knockdown
None of the above
Rigid duct
90
Which of the following are considered mechanical fittings?
Flare and Brazed
Brazed and Soldered
Compression and Flared
Soldered and Flared
91
Conductivity is the measure of _____ and _____ in regard to a material.
Malleability, Capillary action
Heat transfer and Electrical flow
None of the above
Fluid flow, Vapor flow
92
Standard filter driers can be installed in either direction.
False
True
93
A single wall vent connector should only be used when the distance from the furnace to the flue outlet is very long.
True
False
94
It is not important to keep the inside of the suction and liquid lines clean.
False
True
95
The definition of an alternate heating system is which of the following::
A system that uses only man-made fuel as a source
A system that uses any FuelSource that is not NaturalGas,propane,or FuelOil
A system that uses only wood as its fuel source
A system that uses natural gas, propane, or fuel oil as its sourc
96
P-traps should be placed at the bottom of suction risers.
False
True
97
Brazing is used to create joints in such applications as ______________.
ABS water lines
All of the above
High-pressure refrigeration lines
High-pressure stream lines
98
4
False
True
99
Oxygen acts as an accelerator that enables a substance to burn at a much faster rate
True
False
100
It is best practice to flow Nitrogen every time you braze a refrigerant line.
False
True
