Commerial HVAC Drawing Flashcards
1
Q
What temperature does a CAV NUA supply?
A
Near room tempurature
2
Q
What is a typical neutral deck summer terminal?
A
75*F to 80*F
3
Q
What type of climate would you install a Single Duct VAV System?
A
A place where it is continuously warm climate.
The RTU doesn’t have a heat exchanger.
Baseboard heaters of heat coils in VAV proved heat to room.
4
Q
What type of damper blades are used in FB (face bypass) systems to provide more accurate zone comfort conditions?
A
Opposed Blade Dampers
5
Q
How many actuators does a CAV dual duct terminal have?
A
Single Actuator controling S/A temperature from a zone thermostat.
6
Q
What is a :
Recirculating Direct Fired Make-Up Air Unit?
A
A Direct Fired MUA that can utilize return air.
7
Q
What percentages do Variable Air Volume systems save on electric and fuel consumption?
A
20% to 30%
8
Q
What is the prime consideration when using FB (face bypass) with a DX coil?
A
You must have a Evaporator Capacity Control
9
Q
Single Duct VAV systems adjust the volume of the air entering the space.
True or False
A
True
10
Q
How do AHU (air handling units) provide the proper supply air temperature?
A
- Hot or Chilled water Coils
- DX (refigerant)
- Steam Coils
- Heat Recovery
- Heating Elements
- Steam Grids
- Economizer functions
11
Q
What are MUA (make-up air units) used for?
A
To replace the air that is expelled by a building’s exhaust system, maintaining the proper balance between inside and outside air pressure.
12
Q
Whatv are IFMUA heat exchangers made of?
A
Stainless Steel
13
Q
What is the coldest expected coil temperature of an induction cooling terminal?
A
Coil temperatures cooler than 50*F often cause condensation problems.
14
Q
What sizes of pipe with rtaes of flow will produce 1 Ton of Cooling?
A
- 5/8” OD pipe (2.4gpm @ 6 fps)
- 8” Spiral (400 cpm @ 1200 fpm)
- 5” Spiral (400 cfm @ 3000 fpm)
15
Q
List 4 CAV HVAC systems.
A
- Unitary or Stand Alone
- Single Zone
- Multi Zone
- Under Floor
16
Q
How does a bypass VAV system vary the volume of air being delivered to a space?
A
The bypass varies the air volume in the spaces by cycling unneeded conditioned air back to the central unit without allowing it to pass through the spaces.
17
Q
List 4 types of control agents used to affect temperature changes in HVAC systems?
A
- All Air
- All Water
- Air and Water
- Direct Refigerant (DX)
18
Q
List the 2 different types of fan powered terminal units.
A
- Constant volume (series flow)
- Variable volume (parallel flow)
19
Q
Why is control of a VAV system critical?
A
Without proper and rapid flow rate control , either the systems’s ductwork or sealing can be damaged by over pressurization.
20
Q
What will happen in some HVAC systems that are zoned if no bypass damperis installed?
A
Too much air may try to go to this zone and create excessive noise and uncomfortable drafts and can cause damage to the HVAC unit.
21
Q
What are the 2 basic categories of air distribution systems ?
A
- CAV - constant Air Volume System
- VAV - Variable Air Volume System
22
Q
Explain the difference between a regular VAV systems and a True VAV system.
A
The regular VAV system does not change the speed of the fans like a true VAV system does.
The regular VAV system uses dampers to throttle or bypass the air to control its quantity.
23
Q
List the 4 types of VAV systems.
A
- Single Duct
- Dual Duct
- Bypass
- True VAV
24
Q
What is the issue with a CAV Mixed Air System?
A
It is not proficient at controlling the humidity
25
What temperature is air delivered at in a CVS single zone reheat system?
55\*F (13\*C)
26
What devices controls the motorized dampers?
The CENTRAL CONTROL PANEL is a computer that controls the function of all dampers that are connected to it.
27
What controls the mixing damper actuator in a multi-zone system?
An indendant zone theramostat.
28
List the five (5) advantages to using VAV diffusers.
1. Individual space control; and comfort
2. Control of the required air volume for each zone
3. ease of installation and relocation
4. flexibity for future requirements
5. Ease to maintenance
29
What does the acronym VAV stand for?
Variable Air Volume
30
What is the supply air temperature of a VAV system?
55\*F
31
What is the acronym UFAD?
Under Floor Air Distrabution
32
A True VAV sytem varies the __ \_\_\_\_ to control the temperature in a space.
air volume
33
How do VAV systems control building static pressure?
Use a variable CFM supply fan.
34
Define : DUAL DUCT NON-MIXING
Dual duct VAV terminals use 2 duct inlets :
1 supplying warm tempered air while the other is supplying cool air. There is no mixing of these airstreams, just a simple opening or closing of either damper depending on whether the thermostat is calling for heating or cooling
35
What controls the Reheat Terminal in the Terminal Reheat System?
A zone thermostat that controls a zone valve that modulates the flow of heated water or steam.
36
Describe the difference between a multizone and a three deck multizone system.
The three-deck system is similar to the dual duct and multi-zone systems, except that there is an additional (third) air stream that is neither heated nor cooled.
37
What are 2 types of DUCT Terminations ?
1. Dual Duct Mixing
2. Dual Duct NON-Mixing
38
With CAV Multi-zone sytems Air Handing Unit, what are the typical hot and cold deck temperature in a multi-zone system?
90\*F to 55\*F
39
What controls the preheat coil in the Terminal Reheat System?
Zone Independant Thermostat
40
List 2 types of MUA (make up air) units.
1. Direct Fire
2. Indirect Fire
41
What controls hot and cold deck temperature in a multi-zone system ?
The RTU.
approx. 90\*F to 55\*F
42
The bypass VAV system uses the ______ or _______ of a ______ \_\_\_\_\_\_ to control the space temperature.
opening or closing of a volume damper
43
List the 2 deffierent types of bypass dampers
1. Barometric Damper
2. Motorized Damper
44
A dual duct system maintains the temperature in the space by doing what?
Increasing or decreasing the quantity (volume) of heated or colled air.
45
How does a multi-zone unit control the temperature of the air that is being distributed through the ducts?
The mixing of the airstream is done at the central air unit with the use of a set of interlocked motorized dampers.
46
When is it acceptable to use a DFMUA to DFMUA to areas with sleeping accommodation?
NEVER
47
List 3 components of a DCV (demand control Ventilation) control System.
1. BAS systems with baseline schedules
2. Motion sensors to confirm occupancy
3. CO2 Exhaust sensors to monitor IAQ (indoor air quality)
48
What is the air temperature that is delivered from the central air handling unit in a CVS (constan volume system)?
55\*F (13\*C)
49
What is an advantages of a True VAV System?
Excellent Humdity Control
50
On what princple does an induction terminal unit work?
The induction terminal unit uses primary air supply flowing through a nozzle or group of nozzles to induce room air flow through the terminal heating and cooling coils.
51
List the 3 applications of direct fired makeup air systems.
1. Make Up heating / cooling
2. Space heating
3. Space pressure control
52
How many actuators does a DDVAV Mixing Terminal have?
2 Actuators
53
VAV systems are perferred because of their energy saving capabilities.
YES or NO
Yes
54
Define : DUAL DUCT MIXING
The 2 airstreams are mixed in the terminal and the air is discharged at a predetermined temperature through a single duct.
55
What are the 2 primary atvantages to VAV systems?
1. Fan capacity control
2. Defumidifaction
56
What devices controls the motorized dampers?
The CENTRAL CONTROL PANEL is a computer that controls the function of all dampers that are connected to it.
57
What happens to the bypass air from a VAV bypass terminal?
The air is bleed into the mechanical space and returns into the R/A of the AHU
58
What does the acronym CV-VT represent?
Constant Volume - Varying Temperature
59
What is the difference between a Direct Fire MUA and Indiect Fire MUA?
* Direct Fire MUA releases products of combustion into supply air
* Indirect Fire MUA has a heat exchanger and vents the products of combustion outside building.
60
What does the term "Bucking" mean in a multu-zone system ?
It is an inefficient operating of concurrently heating and cooling the air.
61
In a cooling only FB (face bypass) system what position will the dampers be in, if the zone temperature is below the thermostst set-point?
Closed Position
No call for cooling. No air through cooling coil.
62
In a single zone RTU system , where is the air conditioned?
In the air handling unit.
63
Dual Duct VAV systems blend the cooled and heated air at the air handling unit and then distribute it throught the ductwork to the terminal units.
True or False
False
64
What 2 types of CAV systems that are commonly used to modify the supply air temperature?
1. Terminal Reheat System
2. Mixed Air System
65
What is the range of the ductwork static pressure classification?
1/2 w.c. to 10" w.c.
66
What must be done when you are referring to a fresh set of blueprints on a new job site?
A. Compare site conditions to the blueprint when ordering material.
B. Check measurements on the blueprint and compare them to the job site
C. Communicate immediately with other trades on the job site to see if there is anything of which are good recommendations when starting a new project.
D. All the above are good recommendations when starting a new project.
D. All the above are good recommendations when starting a new project.
67
List 3 reasons for checking the blue print and site prior to starting work.
1. Sometimes plumbers and electricians have to install piping in places other than what is known on the blue print
2. To avoisd conflicts with other trades during the installation.
3. To make sure that the material you are ordering is the right material.
68
A fitting or duct should be named and _______ clearly as to where it is going and what HVAC equipment it is associated with on the job site.
A. categorized
B. evident
C. labelled
D. sorted
C. labelled
69
What drawing accessary is used to aid in presenting standardized fabrication shop drawings?
Drawing Template
70
Whatever type of drawing style is being used, it must be ______ , ______ , and _____________________ .
Whatever type of drawing style is being used, it must be NEAT, LEGIBLE and DISP[LAY ALL THE REQUIRED INFORMATION FOR THAT FITTING.
71
Using a _____ \_\_\_\_\_ is a good way of promoting standization when compiling an itemized list of materials.
Using a STANDARD FORM is a good way of promoting standization when compiling an itemized list of materials.
72
The letters STD indicate standard (non-variable volume) air duct construction requirements.
TRUE or FALSE
TRUE
73
The letters STV indicate the standard construction classification for variable volume ducts.
TRUE or FALSE
TRUE
74
Beaded sleeves that join transverse round ducts must be:
At least the same gauge as duct and 4" long minimum
75
By how many inches should round duct transverse joints that are beaded and crimped slip into one another?
1"
76
What is the most commonly used for tound duct reinforcement?
1. hoop hangers
2. angle rings
3. welded collars
4. S-cheats
2. angle rings
77
SMACNA refers to the part of a fitting collar that slips into the large end of a spiral pipe. What is this part called?
1. bead and collar
2. slip collar
3. spigot
4. tap in
3. spigot
78
All duct constructed for the 1" (250Pa) and 1/2" (125Pa) pressure class must meet which Seal Class?
Seal Class C
79
Why is it important to learn proper duct construction methods?
Design duct that will :
* Produce enough static pressure to over come the resistance of the duct
* Maintain the required air velcities and volumes.
80
According to SMACNA, what type of information are design professionals required to include in all plans, blue prints and HVAC duct construction
1. Comprehensive duct layout indicating sizes, design air flows, pressure class and routing of the duct system.
2. Types of fittings to be used based on the designers calculation of fitting losses.
3. Use of turnig vains or splitters.
4. Location of access doors.
5. Location and type of controls and balancing dampers.
6. Location and type of diffusers.
7. Requirements for duct insulation.
8. Location and types of any fire protective devices. Build Code requires to be on print for submittal.
9. Details of offsets required to route ductwork around obstructions.
81
What does the duct construction and installation standards in SMACNA include for information?
SMACNA includes :
* Illustrations
* Optional alternatives
* General requirements.
* Procedural and performance reqquirements for specific items.
82
Other topics in SMACNA included are considerstions relating to liquids, mastics, gaskets, tapes, heat applied materials and embedded fabic.
State the considerations.
* Surface Preparation
* Sealant Strength
* Shelf Life
* Safety Considerations
83
What type of water gauges does the sheet metal industry use?
Sheet metal uses w.c. (water column), BUT can still use w.g. (water gauge).
84
What manual do you use for duct construction?
SMACNA
Sheet Metal Air Conditioning Contractors' National Association
85
Who enforces that the building codes of duct construction are met?
Alberta Building Code
It states that all ductwork and fittings should be build and installed as per SMACNA and ASHRAE
86
What does ASHRAE
American Society of Heating, Refrigeration and Air Conditioning Engineers.
87
What are the pressure classifications used today in duct construction?
* STD - Standard Non-Variable Volume Ducts
* STV Standard Variable Volume Ducts
88
A duct system may contain dusts that are under both ______ pressure and ______ pressures.
A duct system may contain dusts that are under both POSITIVE pressure and NEGATIVE pressures.
89
When NO pressure classes are specified by the designer, what classes are to be used as the basis of compliance.
* 1" w.c. (250pa) pressure class, regardless of velocity in the duct.
EXCEPT when its variable velocity
* All varible velocity duct upsteam of VAV will be 2" w.c. (500pa)
90
When ordering Acoustically lined duct, what must be ensured?
The inside dimentions must still the same as print.
The duct must be ordered larger by 2".
1" per side for 1" insulation.
91
The function of moving air through a duct assembly must satisfy what 8 essential performence or operational criteria?
1. Dimensional Stability
2. Thermal Coductivity
3. Seismic Restraint
4. Leakage Control
5. Vibration
6. Noise
7. Exposure to Elements/Polutants
8. Support
92
How much thicker must Aluminum be over galvnized iron?
Aluminum must be 44% thicker to make same standards as galvanized iron.
93
Residential duct system are generally what pressure classification?
Low pressure consisting of
* 1/2 " w.c.
* velocities of 1000 fpm or less in main truck line
94
Fibrous ducts can be used in system that operate up to what ?
* 2" w.c.
* 2400 fpm
95
Why in large commercial systems are higher velocities and pressures are used in the main duct systems
Physical mechanic space requirements.
96
With Industrial Duct Systems, what is the range of the pressures in the duct?
plus or minus 30" w.g. (water gauge)
97
What are the 5 classifications of industrial duct?
1. Class 1 - Non-abrasive, non-corrosive, and gaseous emission control.
2. Class 2 - Conveyance of light to moderately abrasive particulate in light concertration.
3. Class 3 - Applications with highly abrasive particulate in low concentrations.
4. Class 4 - Applications with highly abrasive particulated in high concertrations.
5. Class 5 - Corrosives, such as acid vapour.
98
What are some of the differences between Light Commercial and Large Commercial?
Large Commercial uses
* Higher velocities and pressures in main trunk lines.
* Is more rigid, air tight duct construction.
* Use of fire protection. (fire dampers, etc)
99
According to SMACNA, define : Duct Construction Standards.
Relationship between static pressure, wall thickness, width and durability.
100
What are the 2 things must be determined before you can design the ductwork?
1. Load calculations
2. Type of distribution system
101
When designing a duct system, what are some major considerations?
1. Material choices
2. Methods of ductwork construction
3. Economics of duct system
4. Duct system layout
5. Duct air leakage
6. Acoustic considerations
7. Testing, adjusting and balancing
102
Define Transverse Joint
SMACNA refers to :
* the Longitudinal as a seam and Transverse as a joint. A seam is securing together two longitudinal oriented edges of duct in the direction of airflow.
* a joint is the Transverse connection that connects the end of one duct section to another.
103
What are the Sealant characteristics that you must be considered when sealing duct?
1. If it is Underwriters Laboratories 723 classification
2. NFPA (National Fire Protection Association) 90A or 90B rating
3. Strength and Adhesion
4. Permanently flexible
5. Minimum Shrinkage
6. Resistance to UV, water and mildew
7. No sag
105
Most sealants is what chemical base?
Water Base
106
How many sealant classes are there?
3 Sealant Classes
A,B,C
107
Where is Seal Class A used?
All 4"w.c. (750pa) and up
* Tranverse joints
* Longitudeinal seamsd
* Duct walls penetrations
108
Where is Seal Class B used?
3' w.c. (750pa) and up to 4"w.c. (1000pa)
* All tranverse joints
* Longitude seams
109
Where is Seal Classes C used?
2" w.c. (500pa) to 3" w.c. (750pa)
* Transverse joints only
110
What is the shelf life of a sealant?
6 months or less
111
A pressure test is NOT required on high pressure systems?
TRUE or FALSE
FALSE
112
Connecting sleeves for round duct should be what gauge?
At LEAST the same gauge or thicker than the round duct.
113
How many screws are required to secure round duct up to 14" diameter?
3 screws in uniform intervals.
114
What are some different longitudinal seams used on round duct?
* Spiral Seam
* Butt Seam
* Grooved Seam ( pipe lock , flat lock)
* Snap Lock
115
What is the most popular transverse joint used in round duct?
Slip or Lap types
116
What is a way you can reinforce large round duct?
Angle Rings
117
Saddle take-offs should be sealed after installation on a round pipe.
TRUE or FALSE
TRUE
118
A beaded seam collar should be a minimum of how long?
4 inches
119
How many parts to duct hanging?
3 Parts :
1. Upper Attachment
2. Hanger
3. Lower Attachment
120
What is used in rectangular duct construction for reinforcement?
Exterial reinforcement using these structure shapes.
* Angle
* Hat Section
* Channel or Zee
* Framing Channel
121
What can industrial duct systems go up to on the w.c. (water column)?
30 w.c. (water column)
123
When ordering a Primary Plenum it should fit what?
The equipment that is designed to create static pressure in the air before it is released into the duct system.
124
Can you order duct from only a blueprint without site confirmation?
No, because you don,t see conflicts between the other trades.
125
What is a Extended Plenum
Is a plenum that is tapped into a box or Primary Plenum, using same dimensions.
126
Are rectangular duct take-offs a custom item?
TRUE or FALSE
TRUE
127
Side Takeoffs (STO) come in what standard sizes?
4" to 24"
128
Saddle Takeoffs come in what standard sizes?
4" to 18"
129
Spin Collars or Tap-In Collars come in what standard sizes?
4" to 14"
130
What do you state when ordering Fire Dampers?
Nomenclature = duct size (width/heigth in ") and V or H and A or B.
1. First letter specifies whether it is Vertical or Horizontal.
2. Second letter specifies whether it has blades in stream or out of stream.
131
A vertical fire dampers is installed how in a duct line?
Mounted in vertical wall to horizontal duct.
132
How is a horizontal fire damper installed?
It is mounted in a horizontal floor or ceiling, connected to vertical duct.
133
State the 3 types of fire damper.
A - blades in stream
B - blades out of stream
C - for round duct
134
When ordering angle for a job, what gauge do we use?
16 gauge
