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HVAC - Variable Air Volume Systems
A.
Bhatia
Overview
In central air
conditioning systems there are two basic methods for delivering air to the
conditioned space:
1) constant air volume (CAV)
systems, and
2) variable air volume (VAV)
systems
As the name implies,
constant volume systems deliver a constant air volume to the conditioned space
irrespective of the load. VAV systems, on the other hand, are designed to
simultaneously meet a variety of cooling and heating loads in a relatively
efficient manner. The system achieves this by varying the distribution of air
depending on the cooling or heating loads of each area. The air flow variation
allows for adjusting the temperature in a single zone without changing the
temperature of air in the whole system, minimizing any instances of overcooling
or overheating. This flexibility has made this one of the most popular HVAC
systems for large buildings with varying conditioning needs such as office
buildings, schools, or apartments.
This 6-hour course covers
HVAC air distribution systems with the focus being on Variable Air Volume (VAV)
systems. The course is entirely based on US Corps of Engineers Construction
Engineering Research Laboratory (USACERL) technical report 99/20, May 1999.
The student must take a multiple-choice quiz consisting of
thirty (30) questions at the end of this course to obtain PDH credits.
Specific Knowledge or Skill Attained
This course teaches the following specific knowledge and
skills:
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What is the operational
philosophy of variable air volume (VAV) systems?
-
What are the differences
between pressure dependent, pressure independent and volume limiting VAV
boxes?
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What are the various
types of fans used in air handling systems including forward curved, backward
curved, radial and aerofoil construction?
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What are the different
types of cooling coils used in air handling systems and which among face
split, vertical split and interwined coils is appropriate for VAV systems?
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What is duct pressure
classification and how it is used in selecting appropriate duct sheet
thickness?
-
How is duct design using
equal friction method different from static regain and T-method?
-
What are different types
of outlets and which parameters govern their selection?
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What is the difference
between fan powered, single duct, dual duct and bypass VAV boxes?
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What are different types
of VAV controls including direct digital controls?
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What are the common
instruments used in acceptance testing and monitoring of VAV systems?
Course
Click on the link below to view the documents prior to taking a
quiz for PDH credits.
HVAC - VAV Systems (6.3 MB)
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credit. Click on the link below.
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