Which of the following is/are disadvantages of a zoned variable air volume system?
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( )Poor energy efficiency since so much energy is used for fans
(x)Possibly poor ventilation if a zone does not require much air for cooling
( )Difficult to adapt to an air-side economizer
( )Difficult to control to achieve the desired effect in each zone
, This system uses an air-conditioning unit to cool primary air, and terminal units in the
zones supplied with hot or cold water to achieve the final temperature
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( )All-air system
(x)Air-and-water system ← Correct answer
( )All-water system
( )None of these answers
In an air-and-water system, most of the heating and cooling is provided by water. The
air system only deals with ventilation needs, and hence there will be less airflow and
less dilution of contaminants. To compensate for this
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(x)The central system filters should be of higher efficiency than those
typically used in all-air systems ← Correct answer
( )Windows should be opened when the space is occupied by many
people
( )An economizer should be set up to bring in more outdoor air into the
space
( )Fans should be incorporated to increase the airflow between zones
when required
This system uses an air-conditioning unit to cool primary air, and does not provide any
supplementary cooling units in the zones. Heating may be provided by the primary air
stream or by terminal units in the zones
Give this one a try later!
Give this one a try later!
( )Poor energy efficiency since so much energy is used for fans
(x)Possibly poor ventilation if a zone does not require much air for cooling
( )Difficult to adapt to an air-side economizer
( )Difficult to control to achieve the desired effect in each zone
, This system uses an air-conditioning unit to cool primary air, and terminal units in the
zones supplied with hot or cold water to achieve the final temperature
Give this one a try later!
( )All-air system
(x)Air-and-water system ← Correct answer
( )All-water system
( )None of these answers
In an air-and-water system, most of the heating and cooling is provided by water. The
air system only deals with ventilation needs, and hence there will be less airflow and
less dilution of contaminants. To compensate for this
Give this one a try later!
(x)The central system filters should be of higher efficiency than those
typically used in all-air systems ← Correct answer
( )Windows should be opened when the space is occupied by many
people
( )An economizer should be set up to bring in more outdoor air into the
space
( )Fans should be incorporated to increase the airflow between zones
when required
This system uses an air-conditioning unit to cool primary air, and does not provide any
supplementary cooling units in the zones. Heating may be provided by the primary air
stream or by terminal units in the zones
Give this one a try later!
