CEM 472 Final Exam || with 100% Verified Solutions.
Define Ducts correct answers hollow pipes that convey air in an HVAC system
Define Duct Fittings correct answers sections of duct that change the direction or manner of flow
Duct materials correct answers Rigid Steel or aluminum sheet metal, fiberglass/metal composite
with metal wire coil (flexible ducts)
Duct Shapes (3) and benefits from each correct answers -Circular - most efficient (volume of air/
material used)
-Oval - efficient but shallower
-Rectangular - allow more head room, shallower cross sections
Duct Insulation Purposes (2) correct answers -Acoustical - reduce noise
-Thermal - Reduce heat transfer
R-5 correct answers Minimum R value for unconditioned spaces and to separate plenum space
from exterior
Duct Mastic (2 properties) correct answers Thick adhesive applied wet to fill gaps and dries to
soft solid, flexible and can therefore move with thermal expansion and vibrations
Dampers (Define) correct answers A bladed device used in ductwork to vary the volume of air
through the outlet, inlet, or duct
Dampers are used in a _______ system to ensure the proper airflow to the right spaces correct
answers balancing
Fire Dampers (How they work & what activates them) correct answers Automatically close,
triggered by a FUSIBLE LINK
Fire Dampers are installed where? correct answers In the plane of the fire wall
Smoke dampers (How they work) correct answers Use walls and floors as barriers to create
zones of pressure. They are triggered by smoke or heat detectors. Need electrical sub
coordination
Outlets (Define & How they are selected) correct answers an opening where air is introduced
into the space, selected to ensure both occupant comfort and adequate ventilation
Quantity and Quality of air flow to space is controlled by correct answers Throw and Spread of a
diffuser or grille
Diffusers (What are they) correct answers Outlets with built in louvers or deflectors that throw
and disperse supply air
, Grilles (What are they) correct answers Sets of vertical and horizontal vanes that are typically
FIXED (return air, typically)
Registers (What are they) correct answers A grille with a build in damper
Axial Fans Airflow & Connection correct answers Airflow is parallel to the axis of rotation of
blades, directly connected to motors to avoid losses associated with drive belts
Centrifugal Fans (Squirrel Cage Fans) Airflow & Special notes correct answers Airflow is
parallel to the axis of rotation, mass of the fan is farther from axle requiring more starting torque,
but generally quieter
Air Handling Unit (AHU) ( Components) correct answers Fan, fan drive, coil, filter contained in
a cabinet
Fan Filter Unit (FFU) correct answers Combines the filter and fan in an AHU
Types of air in buildings (7) correct answers -Supply air - from AHU to space
-Return air - from space to AHU
-Re-circulated air - space to AHU to space
-Exhaust air - from space to outdoors
-Make-up air - replaces exhaust air
- Ventilation (outdoor, fresh) air - from outdoors to space
- Mixed air - combination of air types
(CAV) Constant Air Volume (Important Note) correct answers May require re-conditioning at
terminal units containing re-heat coils
(VAV) Variable Air Volume (Important Note) correct answers Controlled by dampers at
Terminal Units (TU's) (VAV boxes)
(TU's) Terminal Units (Do What) correct answers One TU defines one thermal zone
Zones (Define) correct answers A space controlled by a thermostat, and defined by a terminal
unit which controls flow and heat transfer
Positive vs. Negative pressure in buildings/zones correct answers Positive Buildings allow air to
exfiltrate to outdoors
Negative Buildings allow air to infiltrate from outdoors
ERV correct answers Energy Recovery Ventilator
(ERV) Energy Recovery Ventilator (Alternate Name) correct answers Heat Recovery Ventilator
(HRV)
Define Ducts correct answers hollow pipes that convey air in an HVAC system
Define Duct Fittings correct answers sections of duct that change the direction or manner of flow
Duct materials correct answers Rigid Steel or aluminum sheet metal, fiberglass/metal composite
with metal wire coil (flexible ducts)
Duct Shapes (3) and benefits from each correct answers -Circular - most efficient (volume of air/
material used)
-Oval - efficient but shallower
-Rectangular - allow more head room, shallower cross sections
Duct Insulation Purposes (2) correct answers -Acoustical - reduce noise
-Thermal - Reduce heat transfer
R-5 correct answers Minimum R value for unconditioned spaces and to separate plenum space
from exterior
Duct Mastic (2 properties) correct answers Thick adhesive applied wet to fill gaps and dries to
soft solid, flexible and can therefore move with thermal expansion and vibrations
Dampers (Define) correct answers A bladed device used in ductwork to vary the volume of air
through the outlet, inlet, or duct
Dampers are used in a _______ system to ensure the proper airflow to the right spaces correct
answers balancing
Fire Dampers (How they work & what activates them) correct answers Automatically close,
triggered by a FUSIBLE LINK
Fire Dampers are installed where? correct answers In the plane of the fire wall
Smoke dampers (How they work) correct answers Use walls and floors as barriers to create
zones of pressure. They are triggered by smoke or heat detectors. Need electrical sub
coordination
Outlets (Define & How they are selected) correct answers an opening where air is introduced
into the space, selected to ensure both occupant comfort and adequate ventilation
Quantity and Quality of air flow to space is controlled by correct answers Throw and Spread of a
diffuser or grille
Diffusers (What are they) correct answers Outlets with built in louvers or deflectors that throw
and disperse supply air
, Grilles (What are they) correct answers Sets of vertical and horizontal vanes that are typically
FIXED (return air, typically)
Registers (What are they) correct answers A grille with a build in damper
Axial Fans Airflow & Connection correct answers Airflow is parallel to the axis of rotation of
blades, directly connected to motors to avoid losses associated with drive belts
Centrifugal Fans (Squirrel Cage Fans) Airflow & Special notes correct answers Airflow is
parallel to the axis of rotation, mass of the fan is farther from axle requiring more starting torque,
but generally quieter
Air Handling Unit (AHU) ( Components) correct answers Fan, fan drive, coil, filter contained in
a cabinet
Fan Filter Unit (FFU) correct answers Combines the filter and fan in an AHU
Types of air in buildings (7) correct answers -Supply air - from AHU to space
-Return air - from space to AHU
-Re-circulated air - space to AHU to space
-Exhaust air - from space to outdoors
-Make-up air - replaces exhaust air
- Ventilation (outdoor, fresh) air - from outdoors to space
- Mixed air - combination of air types
(CAV) Constant Air Volume (Important Note) correct answers May require re-conditioning at
terminal units containing re-heat coils
(VAV) Variable Air Volume (Important Note) correct answers Controlled by dampers at
Terminal Units (TU's) (VAV boxes)
(TU's) Terminal Units (Do What) correct answers One TU defines one thermal zone
Zones (Define) correct answers A space controlled by a thermostat, and defined by a terminal
unit which controls flow and heat transfer
Positive vs. Negative pressure in buildings/zones correct answers Positive Buildings allow air to
exfiltrate to outdoors
Negative Buildings allow air to infiltrate from outdoors
ERV correct answers Energy Recovery Ventilator
(ERV) Energy Recovery Ventilator (Alternate Name) correct answers Heat Recovery Ventilator
(HRV)
