Commercial Exam Study Flashcards
NMS is national master specification is comprehensive library of construction standards
True
How do you motorized zone dampers contribute to energy efficiency in residential HVAC
By conditioning the zones only required
What is the purpose of a bypass damper in multi zone residential
To relieve pressure and prevent damage to the equipment
What is the purpose of light commercial multi zone equipment
Temperature control in each zone 
?
?
Why are VAV terminals popular in light construction
VAV terminals all for versatility for change easy to move later 
What is the function of a single duct terminal unit in a VAV system and where are they typically found
Single duct terminal units supplied condition air constant volume and temperature mostly found in interior zones
What distinguishes Large commercial multi zone equipment from other types of zoning
Pressurized loops and different types of vav terminals
How do dual duct non-mixing VAV terminals function and where are they commonly used
They use hot and cold ducts adjusting dampers based on temperature needs used in constant airflow like hospitals
What are two main types of HVAC systems discussed in commercial setting
CAV
Vav
What are primary types of CAv systems and How are they modified for supply temperature
Used in small buildings with reheat coils
What’s the primary benefit of regular vav
Precise air amounts reducing consumption for smaller equipment
Single duct vav and there temperatures
Volume control dampers and adjusting air flow based on zone thermostat
How do bypass vav systems work
Bypass systems conditioned air without going through the occupied space. Not very efficient
Why is make up air needed
Prevent negative air so there are no issue trying to open doors , backdraft from gas appliances
Two types of gas fired makeup air units
Indirect
And direct
Two types of fans and classes
Axial (propeller)
Centrifugal (radial )
How dose air in axial fans work
Leaves the fan in the same direction it went in
Characteristics of a propeller fan
Low rpm large volume of air with low static pressure
What are cross flow fans and uses
They have a crossing pattern used on wall curtains for doors
What temp is going into single duct vav box and what might be added
55f and a heating coil
What are air extractors
Installed in main ducts where splitters can be installed
What are some common methods for sound and noise control
Silencers , fan isolation mount, sound traps
Describe CAV system
Supply air flow rate is constant supply air temperature is Varied
What’s is buckling
Heating and cooling at the same time
What happens to the ducts in a high velocity system
They are reduced
What’s used to slow down air in high velocity
Attenuator
When low temp enters system. What’s used to heat before it’s conditioned
Reheat coil
Single VAV systems adjust volume of air entering the space
True
Dual dock VAV system blends cold and heated air at air handling unit true or false
False
Vaneaxial fans are what Efficiency
Most efficient
Thousand CFM of air to remove through duct system it’s a pressure of 0.4 What motor works best
Forward curved blade centrifugal
What type of blade arrangement is usually use an air pollution high particle loads
Radial
The most accurate volume control air is obtain by using
Oppose blade dumper
What type of isolation valves come in pairs
Isolation rails 
Or additional mass is required what base do you use
Inertia bases
How are free standing isolators determined
Colour coated coil springs to load capacities
What is used forFloor isolators
Rubber
Types of material use for acoustical lining
Fibreglass has become the most frequently may use material
H
N
Types of air washers
Spray type
Cell type 
Dry media filters increase efficiency as they collect material true or false
True
What’s Merv 
Minimum efficiency reporting value
When changes are made to original drawings what the changes made called
Revisions and addenda
Discrepancies in drawings what take president
Written specifications
What is the most note worthly Between residential and light commercial blueprints
Grid lines
Where does the intersection of gridlines usually occur
Centreline of columns
Which callouts are most commonly used for Hvac drawings
Grilling defuses

Who should be consulted when proposed changes
Design engineer
Return air should be ducted to one or several return grill
Only when combustibles are present
When duct is in conditioned space. Is it less of a factor then when it is not
Yes
The most Important verible in air cleaning
Particle size
