BOMA-HVAC ACTUAL UPDATED Exam
Questions and CORRECT Answers
What happens when room temperature soda is poured into a glass of ice ? - CORRECT
ANSWER The ice melts because it is absorbing heat from the soda .
The compressor in a refrigeration system - CORRECT ANSWER pumps the refrigerant
throughout the system
To control ice build - up on a heat pump outdoor coil in the heating cycle a ______ is used . -
CORRECT ANSWER pressure differential switch
The total pressure of a confined mixture of gases is the sum of the pressures of each of the gases
in the mixture . This is known as - CORRECT ANSWER Dalton's Law
When moisture is present in a refrigeration system , it will react with the refrigerant and the oil to
form_ - CORRECT ANSWER acid
A direct expansion - type evaporator is also called a - CORRECT ANSWER dry-type
evaporator
Positive displacement compressors have crankcase heat to - CORRECT ANSWER prevent
refrigerant migration to the compressor
If the power element of a TX valve loses its charge the - CORRECT ANSWER refrigerant
flow to the coil will stop
The pressure in a refrigeration system is changed in the - CORRECT
ANSWER compressor and expansion device
,Where is cooling produced - CORRECT ANSWER In the evaporator
Where is heat content the highest - CORRECT ANSWER Entering the compressor
Where is heat content decreased the most ? - CORRECT ANSWER The condenser
Where is the compressor located - CORRECT ANSWER Between the condenser and
evaporator
Where does the state of refrigerant change from liquid to a vapor - CORRECT
ANSWER The evaporator
What part of the system is pressure the lowest - CORRECT ANSWER The evaporator
(T/F) A Compressor raises the pressure and lowers the temperature of the refrigerant -
CORRECT ANSWER False
Rotary is what type compressor - CORRECT ANSWER Positive displacement
If a thermal expansion valve stays closed what would be the result - CORRECT
ANSWER The valve would not be the load and the unit will heat up
What type of metering device is used in a centrifugal chiller - CORRECT ANSWER A
high side float
Which compressor require the least amount of maintenance - CORRECT
ANSWER Centrifugal
What opens the TXV - CORRECT ANSWER The power element of the assembly
,T/F the purpose of a solenoid valve in a refrigeration system is to start and stop the refrigerant
flow - CORRECT ANSWER True
What causes oil to foam - CORRECT ANSWER Refrigerant in the oil
What determines the corrosion tendency of oil - CORRECT ANSWER The sulfur content
What would cause a compressor to overload - CORRECT ANSWER Starting under a
warm evaporator load
The evaporator im a refrigeration system - CORRECT ANSWER Absorbs heat from the
product to be cooled
Moisture reacts with refrigerant and oil to form - CORRECT ANSWER Acid
A direct expansion type evaporator is also called a - CORRECT ANSWER Dry type
evaporator
The condenser - CORRECT ANSWER rejects the heat from the refrigerant
Positive displacement compressors have crankcase heat to - CORRECT ANSWER Prevent
the refrigerant migration to the compressor
If the power element of a TX valve loses its charge, the___. - CORRECT
ANSWER refrigerant flow to the coil will stop
Most of the heat energy in the suction vapor entering the compressor is - CORRECT
ANSWER Latent heat
, If the thermal bulb assembly develops a leak , what will occur - CORRECT
ANSWER The bulb pressure will reduce and the valve will close
The approach of a cooling tower is the - CORRECT ANSWER difference in temperature
between the entering air wet-bulb temperature and the sump water temperature
At what locations in a refrigeration system does the saturation pressure correspond to the
saturation temperature - CORRECT ANSWER Evaporator and condenser
A split phase motor can use what to energize and de-energize the start winding ? - CORRECT
ANSWER Potential relay, current relay, and a centrifugal switch
Temperature is an indicaron of the - CORRECT ANSWER Amount of molecular activity
in the material
What can cause high suction pressures - CORRECT ANSWER Defective compressor
valves
What can cause an expansion valve to operate erratically - CORRECT ANSWER Vapor in
the liquid line, bad compressor, low refrigerant charge.
What is a probable cause of a broken valve in the compressor - CORRECT
ANSWER Liquid slugging
If a heat pump has insufficient cooling and low suction pressure what is the cause - CORRECT
ANSWER Partially iced coil
If the power circuit and a control circuit of a cooling system are continuous the problem is ? -
CORRECT ANSWER A faulty compressor motor
Questions and CORRECT Answers
What happens when room temperature soda is poured into a glass of ice ? - CORRECT
ANSWER The ice melts because it is absorbing heat from the soda .
The compressor in a refrigeration system - CORRECT ANSWER pumps the refrigerant
throughout the system
To control ice build - up on a heat pump outdoor coil in the heating cycle a ______ is used . -
CORRECT ANSWER pressure differential switch
The total pressure of a confined mixture of gases is the sum of the pressures of each of the gases
in the mixture . This is known as - CORRECT ANSWER Dalton's Law
When moisture is present in a refrigeration system , it will react with the refrigerant and the oil to
form_ - CORRECT ANSWER acid
A direct expansion - type evaporator is also called a - CORRECT ANSWER dry-type
evaporator
Positive displacement compressors have crankcase heat to - CORRECT ANSWER prevent
refrigerant migration to the compressor
If the power element of a TX valve loses its charge the - CORRECT ANSWER refrigerant
flow to the coil will stop
The pressure in a refrigeration system is changed in the - CORRECT
ANSWER compressor and expansion device
,Where is cooling produced - CORRECT ANSWER In the evaporator
Where is heat content the highest - CORRECT ANSWER Entering the compressor
Where is heat content decreased the most ? - CORRECT ANSWER The condenser
Where is the compressor located - CORRECT ANSWER Between the condenser and
evaporator
Where does the state of refrigerant change from liquid to a vapor - CORRECT
ANSWER The evaporator
What part of the system is pressure the lowest - CORRECT ANSWER The evaporator
(T/F) A Compressor raises the pressure and lowers the temperature of the refrigerant -
CORRECT ANSWER False
Rotary is what type compressor - CORRECT ANSWER Positive displacement
If a thermal expansion valve stays closed what would be the result - CORRECT
ANSWER The valve would not be the load and the unit will heat up
What type of metering device is used in a centrifugal chiller - CORRECT ANSWER A
high side float
Which compressor require the least amount of maintenance - CORRECT
ANSWER Centrifugal
What opens the TXV - CORRECT ANSWER The power element of the assembly
,T/F the purpose of a solenoid valve in a refrigeration system is to start and stop the refrigerant
flow - CORRECT ANSWER True
What causes oil to foam - CORRECT ANSWER Refrigerant in the oil
What determines the corrosion tendency of oil - CORRECT ANSWER The sulfur content
What would cause a compressor to overload - CORRECT ANSWER Starting under a
warm evaporator load
The evaporator im a refrigeration system - CORRECT ANSWER Absorbs heat from the
product to be cooled
Moisture reacts with refrigerant and oil to form - CORRECT ANSWER Acid
A direct expansion type evaporator is also called a - CORRECT ANSWER Dry type
evaporator
The condenser - CORRECT ANSWER rejects the heat from the refrigerant
Positive displacement compressors have crankcase heat to - CORRECT ANSWER Prevent
the refrigerant migration to the compressor
If the power element of a TX valve loses its charge, the___. - CORRECT
ANSWER refrigerant flow to the coil will stop
Most of the heat energy in the suction vapor entering the compressor is - CORRECT
ANSWER Latent heat
, If the thermal bulb assembly develops a leak , what will occur - CORRECT
ANSWER The bulb pressure will reduce and the valve will close
The approach of a cooling tower is the - CORRECT ANSWER difference in temperature
between the entering air wet-bulb temperature and the sump water temperature
At what locations in a refrigeration system does the saturation pressure correspond to the
saturation temperature - CORRECT ANSWER Evaporator and condenser
A split phase motor can use what to energize and de-energize the start winding ? - CORRECT
ANSWER Potential relay, current relay, and a centrifugal switch
Temperature is an indicaron of the - CORRECT ANSWER Amount of molecular activity
in the material
What can cause high suction pressures - CORRECT ANSWER Defective compressor
valves
What can cause an expansion valve to operate erratically - CORRECT ANSWER Vapor in
the liquid line, bad compressor, low refrigerant charge.
What is a probable cause of a broken valve in the compressor - CORRECT
ANSWER Liquid slugging
If a heat pump has insufficient cooling and low suction pressure what is the cause - CORRECT
ANSWER Partially iced coil
If the power circuit and a control circuit of a cooling system are continuous the problem is ? -
CORRECT ANSWER A faulty compressor motor
