UA HVAC STAR EXAM WITH QUESTIONS AND
ANSWERS|| ALREADY GRADED A+|| LATEST
UPDATE 2026
A battery is an example of a/an ____________ source. - ANSWER-Direct
current
Direct current flows constantly in one direction. A battery is one source of
direct current. It will always have two poles or terminals, one negative (-) and
one positive (+). The electron flow is from positive to negative inside the
battery. However, the external flow for the electrical circuits is always negative
to positive. The electrons flow in only one direction. Direct current will
continue to flow until the circuit is broken or the source of energy stops
supplying electrons.
Current flowing through a conductor in one direction for a split second, then in
the opposite direction for a split second" would be a good definition of: -
ANSWER-Alternating current
Alternating current is defined as current flowing through a conductor in one
direction for a split second, then in the opposite direction for a split second.
If a pressure gauge reads five psig at sea level elevation, the corresponding
absolute pressure is ___________ psia. - ANSWER-19.7
5.0 psig + 14.7 = 19.7 psia.
Solar ________ is the amount of solar thermal energy produced divided by the
water heating energy demand of the building. - ANSWER-Fractional
The portion of the electromagnetic spectrum to which solar collectors respond is
_____ and near-infrared radiation. - ANSWER-Visible light
,T or F? During winter, Daylight is shorter and the Northern Hemisphere is
angled away from the sun - ANSWER-True
Unless equipped with OSHA or Canadian Standards Association (CSA)
approved ground-fault circuit interrupters, portable electric lighting used in wet
and-or other conductive locations as, for example, drums, tanks and vessels,
shall be operated at ______ volts or less. - ANSWER-12
Receivers are usually required in systems having: - ANSWER-Evaporative
condensers and air-cooled condensers, being constructed with coiled tubing,
contain very little storage space for refrigerant, and therefore systems with such
condensers will generally require a receiver. (Water-cooled condensers of shell-
and-tube type normally have enough volume to serve as receivers, and a
separate or auxiliary receiver in this case is not needed unless the system is
unusually extensive.)
High Efficiency Particulate Arrester (HEPA) filters can remove pollutants
from the indoor air as small as - ANSWER-20-30 microns
Electrostatic air filters use ______ to clean indoor air. - ANSWER-a series of
negatively and positively charged plates
_______ filters work best to prevent air turbulence and allow for a more
even loading of contaminants. - ANSWER-Pleated
The recommended humidity level in homes or buildings is_______ -
ANSWER-40% - 60%
Duct mounted bypass humidifiers allows air from the supply duct to -
ANSWER-Flow directly to the return air duct
,Pass through a "media"
Be heated before entering the humidifier
Humidifiers should only operate - ANSWER-When the air handler blower is
operating
When the humidistat signals for an increase of humidity
What is the maximum hardness of the water allowable for atomizing type
humidifiers? - ANSWER-8-10 grains
High quality energy recovery ventilators - ANSWER-Use a heat exchanger to
absorb heat from the air being
exhausted
To help prevent allergic reactions or upper respiratory problems humidifiers
should be - ANSWER-Cleaned regularly
Treated with algaecides
Drained regularly
To kill mold and algae and to prevent them from contaminating the area
some manufacturers use - ANSWER-UV lights
The required condenser air flow is approximately (CFM) - ANSWER-1000
CFM per ton
A dirty condenser prevents the rejection of heat and causes - ANSWER-High
head pressure
, A condenser fan motor with sleeve bearings should be lubricated - ANSWER-2
times per year
Improper blower pulley alignment can cause - ANSWER-Unnecessary wear
Erratic speed
Premature belt failure
V-Belt tension should be set to about - ANSWER-1 inch
To add refrigerant to a partially charged air conditioning system a technician
should read the manifold gauges and then - ANSWER-Compare to a Pressure
Temperature Chart
Starting up an air conditioning system with the indoor temperature at 85
degrees f and the Rh at 70% would be considered - ANSWER-An excessive
load. This is an excessive load, at 85 degrees it is a high sensible load and with
70% Rh this is considered a high latent load. Sensible plus latent equals the total
heat load. A normal load would resemble a 75 degree indoor temperature with a
55-60% Rh.
During a complete loss of charge condition with a leak on the systems low
side and the systems low pressure cut-out control has opened the
technician must consider - ANSWER-Finding and repairing the leak
Contaminant in the system
The compressor will not start until the system is recharged
After a system evacuation ___________ can cause a micron gauge to rise
from 250 microns to 500 microns before leveling off. - ANSWER-Excessive
contamination
ANSWERS|| ALREADY GRADED A+|| LATEST
UPDATE 2026
A battery is an example of a/an ____________ source. - ANSWER-Direct
current
Direct current flows constantly in one direction. A battery is one source of
direct current. It will always have two poles or terminals, one negative (-) and
one positive (+). The electron flow is from positive to negative inside the
battery. However, the external flow for the electrical circuits is always negative
to positive. The electrons flow in only one direction. Direct current will
continue to flow until the circuit is broken or the source of energy stops
supplying electrons.
Current flowing through a conductor in one direction for a split second, then in
the opposite direction for a split second" would be a good definition of: -
ANSWER-Alternating current
Alternating current is defined as current flowing through a conductor in one
direction for a split second, then in the opposite direction for a split second.
If a pressure gauge reads five psig at sea level elevation, the corresponding
absolute pressure is ___________ psia. - ANSWER-19.7
5.0 psig + 14.7 = 19.7 psia.
Solar ________ is the amount of solar thermal energy produced divided by the
water heating energy demand of the building. - ANSWER-Fractional
The portion of the electromagnetic spectrum to which solar collectors respond is
_____ and near-infrared radiation. - ANSWER-Visible light
,T or F? During winter, Daylight is shorter and the Northern Hemisphere is
angled away from the sun - ANSWER-True
Unless equipped with OSHA or Canadian Standards Association (CSA)
approved ground-fault circuit interrupters, portable electric lighting used in wet
and-or other conductive locations as, for example, drums, tanks and vessels,
shall be operated at ______ volts or less. - ANSWER-12
Receivers are usually required in systems having: - ANSWER-Evaporative
condensers and air-cooled condensers, being constructed with coiled tubing,
contain very little storage space for refrigerant, and therefore systems with such
condensers will generally require a receiver. (Water-cooled condensers of shell-
and-tube type normally have enough volume to serve as receivers, and a
separate or auxiliary receiver in this case is not needed unless the system is
unusually extensive.)
High Efficiency Particulate Arrester (HEPA) filters can remove pollutants
from the indoor air as small as - ANSWER-20-30 microns
Electrostatic air filters use ______ to clean indoor air. - ANSWER-a series of
negatively and positively charged plates
_______ filters work best to prevent air turbulence and allow for a more
even loading of contaminants. - ANSWER-Pleated
The recommended humidity level in homes or buildings is_______ -
ANSWER-40% - 60%
Duct mounted bypass humidifiers allows air from the supply duct to -
ANSWER-Flow directly to the return air duct
,Pass through a "media"
Be heated before entering the humidifier
Humidifiers should only operate - ANSWER-When the air handler blower is
operating
When the humidistat signals for an increase of humidity
What is the maximum hardness of the water allowable for atomizing type
humidifiers? - ANSWER-8-10 grains
High quality energy recovery ventilators - ANSWER-Use a heat exchanger to
absorb heat from the air being
exhausted
To help prevent allergic reactions or upper respiratory problems humidifiers
should be - ANSWER-Cleaned regularly
Treated with algaecides
Drained regularly
To kill mold and algae and to prevent them from contaminating the area
some manufacturers use - ANSWER-UV lights
The required condenser air flow is approximately (CFM) - ANSWER-1000
CFM per ton
A dirty condenser prevents the rejection of heat and causes - ANSWER-High
head pressure
, A condenser fan motor with sleeve bearings should be lubricated - ANSWER-2
times per year
Improper blower pulley alignment can cause - ANSWER-Unnecessary wear
Erratic speed
Premature belt failure
V-Belt tension should be set to about - ANSWER-1 inch
To add refrigerant to a partially charged air conditioning system a technician
should read the manifold gauges and then - ANSWER-Compare to a Pressure
Temperature Chart
Starting up an air conditioning system with the indoor temperature at 85
degrees f and the Rh at 70% would be considered - ANSWER-An excessive
load. This is an excessive load, at 85 degrees it is a high sensible load and with
70% Rh this is considered a high latent load. Sensible plus latent equals the total
heat load. A normal load would resemble a 75 degree indoor temperature with a
55-60% Rh.
During a complete loss of charge condition with a leak on the systems low
side and the systems low pressure cut-out control has opened the
technician must consider - ANSWER-Finding and repairing the leak
Contaminant in the system
The compressor will not start until the system is recharged
After a system evacuation ___________ can cause a micron gauge to rise
from 250 microns to 500 microns before leveling off. - ANSWER-Excessive
contamination
