ESET 444 QZ 3 EXAM 2025 QUESTIONS
AND ANSWERS
This system keeps supply air always at the same temperature, and delivers more or less air as
required to maintain or change the temperature in the space ( )Constant volume
(x)Variable air volume
( )Fan-based temperature control
( )Constant density
This system always delivers the same airflow but the air may be hotter or colder as required to
maintain or change the temperature in the space (x)Constant volume
( )Variable air volume
( )Thermostatic temperature control
( )Constant density
How can a single-duct system be divided into zones with different thermal requirements? (
)Reheat method - Cool the airflow to meet the needs of the zone that needs most cooling, and
then reheat it for the other zones using a heating terminal at the point of entry to each space
( )VAV method - Cool the airflow to meet the needs of the zone that needs most cooling, and
then reduce the volume of air supplied to the other zones using a VAV box at the point of entry
to each space
( )Provide separate hot and cold air flows to each zone
(x)Either reheat method or VAV method could be used
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, An air-side economizer is used when: ( )Most zones in the system require cooling and only one
or two require heating. The system makes cold air to satisfy the majority of the zones and
reheat is applied in the one or two zones that need heating
( )The return air from the space is relatively free from contaminants and CO2. The return air is
then recycled into the space, since it has already been conditioned and will require less energy
to treat.
( )The price of electricity from the grid is greater than the price of on-site generation. An on-site
generator is then used to produce electricity for air-conditioning at lower cost.
(x)The enthalpy of outdoor air is lower than that of the return air. The outdoor air is then used
to provide free cooling, by bringing in more outdoor air than is required to meet needs for fresh
air ventilation.
Reheat systems have many advantages - they permit simple zone control for areas with
different loads, can provide heating or cooling to different areas at the same time, maintains
close control over humidity and offers flexibility when zones are selected at design stage. What
is the main disadvantage? (x)The system uses energy to cool air and then uses energy again to
heat it back up. This is wasteful of energy and uneconomical
( )The system can't be easily changed to provide more zones once it is installed.
( )The system can't be easily metered to determine which zones consumed the most energy
( )The system can't be easily adapted to allow for heat recovery.
Which of the following is/are disadvantages of a zoned variable air volume system? ( )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
Which of the following approaches has the lowest energy consumption: (x)Single-duct zoned
variable air volume
( )Single-duct zoned-reheat constant volume
( )Dual-duct
2 @COPYRIGHT THESTAR 2025/2026
AND ANSWERS
This system keeps supply air always at the same temperature, and delivers more or less air as
required to maintain or change the temperature in the space ( )Constant volume
(x)Variable air volume
( )Fan-based temperature control
( )Constant density
This system always delivers the same airflow but the air may be hotter or colder as required to
maintain or change the temperature in the space (x)Constant volume
( )Variable air volume
( )Thermostatic temperature control
( )Constant density
How can a single-duct system be divided into zones with different thermal requirements? (
)Reheat method - Cool the airflow to meet the needs of the zone that needs most cooling, and
then reheat it for the other zones using a heating terminal at the point of entry to each space
( )VAV method - Cool the airflow to meet the needs of the zone that needs most cooling, and
then reduce the volume of air supplied to the other zones using a VAV box at the point of entry
to each space
( )Provide separate hot and cold air flows to each zone
(x)Either reheat method or VAV method could be used
1 @COPYRIGHT THESTAR 2025/2026
, An air-side economizer is used when: ( )Most zones in the system require cooling and only one
or two require heating. The system makes cold air to satisfy the majority of the zones and
reheat is applied in the one or two zones that need heating
( )The return air from the space is relatively free from contaminants and CO2. The return air is
then recycled into the space, since it has already been conditioned and will require less energy
to treat.
( )The price of electricity from the grid is greater than the price of on-site generation. An on-site
generator is then used to produce electricity for air-conditioning at lower cost.
(x)The enthalpy of outdoor air is lower than that of the return air. The outdoor air is then used
to provide free cooling, by bringing in more outdoor air than is required to meet needs for fresh
air ventilation.
Reheat systems have many advantages - they permit simple zone control for areas with
different loads, can provide heating or cooling to different areas at the same time, maintains
close control over humidity and offers flexibility when zones are selected at design stage. What
is the main disadvantage? (x)The system uses energy to cool air and then uses energy again to
heat it back up. This is wasteful of energy and uneconomical
( )The system can't be easily changed to provide more zones once it is installed.
( )The system can't be easily metered to determine which zones consumed the most energy
( )The system can't be easily adapted to allow for heat recovery.
Which of the following is/are disadvantages of a zoned variable air volume system? ( )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
Which of the following approaches has the lowest energy consumption: (x)Single-duct zoned
variable air volume
( )Single-duct zoned-reheat constant volume
( )Dual-duct
2 @COPYRIGHT THESTAR 2025/2026
