HVAC Excellence Commercial Air
Conditioning ESCO Certification
Multiple compressor systems have a equalization line to;
A. Maintain equal loads on all compressors
B. Maintain equal oil levels on all compressors.
C. Compensate for different pressures in the compressors.
D. Compensate for evaporator pressure drop. - *answers *A. Maintain equal loads on
all compressors
The purpose of a double suction line riser is to;
A. maintain minimum refrigerant velocities under varying loads.
B. compensate if one suction filter - drier becomes plugged.
C. prevent low pressure trips on start up.
D. compensate for evaporator pressure drop. - *answers *A. maintain minimum
refrigerant velocities under varying loads.
To measure superheat, subtract the;
A. low side saturation temperature from the suction line temperature.
B. high side condensing temperature from the suction line temperature.
C. suction line temperature from the ambient temperature.
D. ambient temperature from the suction line temperature - *answers *A. low side
saturation temperature from the suction line temperature.
An air conditioning system is running constantly, but not cooling enough. The suction
line is very cold and the compressor is sweating. This is an indication of;
A.) low refrigerant charge and needs to be leak tested and repaired.
B.) restricted return air flow or a dirty evaporator
C. restricted air flow across the condenser.
D.) damaged return air duct allowing unconditioned air to be drawn into the system. -
*answers *B.) restricted return air flow or a dirty evaporator
Why must a cooling tower or evaporative condenser be blown down periodically?
A. The condenser water approach will begin to narrow.
B. Maintain PH level of the circulated water.
C. To refresh cooling tower or condenser with cooler make-up water.
D. To remove concentration of minerals in the water. - *answers *D. To remove
concentration of minerals in the water.
A customer reports that their system had one of three fan motors replaced last week by
another service company. Now the unit is not cooling properly since the outdoor
temperature has risen. When you arrive and inspect the unit, you find that discharge
pressure is very high. On further examination, all motors are running, but the amp draw
is different on the new motor as compared to the other two motors. This is most likely
the result of:
A. fan motor is running backward
B. the new motor is grossly over sized.
,HVAC Excellence Commercial Air
Conditioning ESCO Certification
C. a defective replacement motor.
D., the fan blade was not changed to match the new motor - *answers *B. the new
motor is grossly over sized.
When pumping down a condensing unit to check the reciprocating compressor valves,
the compressor
should be able to achieve;
A. 10" Hg suction with a 300 psig high side pressure.
B. 30" Hg suction when discharging to the atmosphere.
C. 24" Hg suction with a 100 psig high side pressure.
D. 24" psig suction with a 200 psig high side pressure. - *answers *B. 30" Hg suction
when discharging to the atmosphere.
Direct Digital Control (DCC) is a control process which incorporates a microprocessor,
acting as a digital controller, updates a data-base of internal information through;
A. reverse action of PTC.
B. the common digital feed.
C. the use of Sensors.
D. the use of Sim cards. - *answers *C. the use of Sensors.
If a compressor has a severe burnout, what accessory should be added to clean the
system?
A. A liquid line drier.
B. An accumulator.
C. A suction line drier.
D. An acid core oil separator. - *answers *C. A suction line drier.
The screw-type compressor operates at a high volumetric efficiency because;
A. there is no re-expansion of refrigerant in the clearance space.
B. they are capable of very low speed operation.
C. capacity can be controlled down to 90%.
D. they are used only on small capacity systems. - *answers *A. there is no re-
expansion of refrigerant in the clearance space.
A rooftop package system is cycling on the high pressure control. What are three
possible causes for this problem?
A. Condenser air being re-circulated, plugged metering device, or undercharge.
B. Excessively bent condenser fins, a faulty pressure switch, or undercharge.
C. Dirty condenser, incorrect rotation of condenser fan, or bad compressor valves.
D. Dirty condenser, bent condenser fins, or air re-circulated over the condenser. -
*answers *D. Dirty condenser, bent condenser fins, or air re-circulated over the
condenser.
An true azeotropic refrigerant blend is one which;
, HVAC Excellence Commercial Air
Conditioning ESCO Certification
A must be charged into the system as a liquid.
B. displays the same characteristics as a single refrigerant.
C. has a high temperature glide.
D. may be vented to the atmosphere if it is an HCFC. - *answers *B. displays the same
characteristics as a single refrigerant.
Commercial water cooled condenser systems must incorporate a water circuit that sub-
cools refrigerant by;
A. water flow in the same direction as the refrigerant circuit.
B. counter flowing the water (opposite of the refrigerant circuit).
C. backflow with multiple check valves slowing water flow for better heat transfer.
D. making the water enter the condenser where liquefaction begins. - *answers *B.
counter flowing the water (opposite of the refrigerant circuit)
14.) As refrigerant vapor density decreases, its velocity requirements;
A. increase.
B. decrease.
C. remain the same.
D. reduces by the square root of the pressure. - *answers *A. increase
15.) An oil trap installed in the discharge line on a vertical riser is intended to:
A. help move oil through the system.
B. prevent oil from draining back to the compressor.
C. maintain a constant pressure drop in the discharge line.
D. prevent suction from excessive oil logging. - *answers *A. help move oil through the
system.
When a capillary tube air conditioning system has an undercharge, what happens to the
superheat and subcooling?
A. The superheat increases and the subcooling increases.
B. The superheat decreases and the subcooling decreases.
C. The superheat decreases and the subcooling increases.
D The superheat increases and the subcooling decreases. - *answers *D The
superheat increases and the subcooling decreases.
A thermostatic expansion valve with an external equalization line should be used when;
A. the evaporator has a pressure drop that causes less than a 29°F change in
saturation
temperature
B. the evaporator has a pressure drop that causes more than a 2°F change in saturation
temperature.
C. the system is charge with HFC refrigerant.
D. the condenser has a high pressure drop. - *answers *B. the evaporator has a
pressure drop that causes more than a 2°F change in saturation
Conditioning ESCO Certification
Multiple compressor systems have a equalization line to;
A. Maintain equal loads on all compressors
B. Maintain equal oil levels on all compressors.
C. Compensate for different pressures in the compressors.
D. Compensate for evaporator pressure drop. - *answers *A. Maintain equal loads on
all compressors
The purpose of a double suction line riser is to;
A. maintain minimum refrigerant velocities under varying loads.
B. compensate if one suction filter - drier becomes plugged.
C. prevent low pressure trips on start up.
D. compensate for evaporator pressure drop. - *answers *A. maintain minimum
refrigerant velocities under varying loads.
To measure superheat, subtract the;
A. low side saturation temperature from the suction line temperature.
B. high side condensing temperature from the suction line temperature.
C. suction line temperature from the ambient temperature.
D. ambient temperature from the suction line temperature - *answers *A. low side
saturation temperature from the suction line temperature.
An air conditioning system is running constantly, but not cooling enough. The suction
line is very cold and the compressor is sweating. This is an indication of;
A.) low refrigerant charge and needs to be leak tested and repaired.
B.) restricted return air flow or a dirty evaporator
C. restricted air flow across the condenser.
D.) damaged return air duct allowing unconditioned air to be drawn into the system. -
*answers *B.) restricted return air flow or a dirty evaporator
Why must a cooling tower or evaporative condenser be blown down periodically?
A. The condenser water approach will begin to narrow.
B. Maintain PH level of the circulated water.
C. To refresh cooling tower or condenser with cooler make-up water.
D. To remove concentration of minerals in the water. - *answers *D. To remove
concentration of minerals in the water.
A customer reports that their system had one of three fan motors replaced last week by
another service company. Now the unit is not cooling properly since the outdoor
temperature has risen. When you arrive and inspect the unit, you find that discharge
pressure is very high. On further examination, all motors are running, but the amp draw
is different on the new motor as compared to the other two motors. This is most likely
the result of:
A. fan motor is running backward
B. the new motor is grossly over sized.
,HVAC Excellence Commercial Air
Conditioning ESCO Certification
C. a defective replacement motor.
D., the fan blade was not changed to match the new motor - *answers *B. the new
motor is grossly over sized.
When pumping down a condensing unit to check the reciprocating compressor valves,
the compressor
should be able to achieve;
A. 10" Hg suction with a 300 psig high side pressure.
B. 30" Hg suction when discharging to the atmosphere.
C. 24" Hg suction with a 100 psig high side pressure.
D. 24" psig suction with a 200 psig high side pressure. - *answers *B. 30" Hg suction
when discharging to the atmosphere.
Direct Digital Control (DCC) is a control process which incorporates a microprocessor,
acting as a digital controller, updates a data-base of internal information through;
A. reverse action of PTC.
B. the common digital feed.
C. the use of Sensors.
D. the use of Sim cards. - *answers *C. the use of Sensors.
If a compressor has a severe burnout, what accessory should be added to clean the
system?
A. A liquid line drier.
B. An accumulator.
C. A suction line drier.
D. An acid core oil separator. - *answers *C. A suction line drier.
The screw-type compressor operates at a high volumetric efficiency because;
A. there is no re-expansion of refrigerant in the clearance space.
B. they are capable of very low speed operation.
C. capacity can be controlled down to 90%.
D. they are used only on small capacity systems. - *answers *A. there is no re-
expansion of refrigerant in the clearance space.
A rooftop package system is cycling on the high pressure control. What are three
possible causes for this problem?
A. Condenser air being re-circulated, plugged metering device, or undercharge.
B. Excessively bent condenser fins, a faulty pressure switch, or undercharge.
C. Dirty condenser, incorrect rotation of condenser fan, or bad compressor valves.
D. Dirty condenser, bent condenser fins, or air re-circulated over the condenser. -
*answers *D. Dirty condenser, bent condenser fins, or air re-circulated over the
condenser.
An true azeotropic refrigerant blend is one which;
, HVAC Excellence Commercial Air
Conditioning ESCO Certification
A must be charged into the system as a liquid.
B. displays the same characteristics as a single refrigerant.
C. has a high temperature glide.
D. may be vented to the atmosphere if it is an HCFC. - *answers *B. displays the same
characteristics as a single refrigerant.
Commercial water cooled condenser systems must incorporate a water circuit that sub-
cools refrigerant by;
A. water flow in the same direction as the refrigerant circuit.
B. counter flowing the water (opposite of the refrigerant circuit).
C. backflow with multiple check valves slowing water flow for better heat transfer.
D. making the water enter the condenser where liquefaction begins. - *answers *B.
counter flowing the water (opposite of the refrigerant circuit)
14.) As refrigerant vapor density decreases, its velocity requirements;
A. increase.
B. decrease.
C. remain the same.
D. reduces by the square root of the pressure. - *answers *A. increase
15.) An oil trap installed in the discharge line on a vertical riser is intended to:
A. help move oil through the system.
B. prevent oil from draining back to the compressor.
C. maintain a constant pressure drop in the discharge line.
D. prevent suction from excessive oil logging. - *answers *A. help move oil through the
system.
When a capillary tube air conditioning system has an undercharge, what happens to the
superheat and subcooling?
A. The superheat increases and the subcooling increases.
B. The superheat decreases and the subcooling decreases.
C. The superheat decreases and the subcooling increases.
D The superheat increases and the subcooling decreases. - *answers *D The
superheat increases and the subcooling decreases.
A thermostatic expansion valve with an external equalization line should be used when;
A. the evaporator has a pressure drop that causes less than a 29°F change in
saturation
temperature
B. the evaporator has a pressure drop that causes more than a 2°F change in saturation
temperature.
C. the system is charge with HFC refrigerant.
D. the condenser has a high pressure drop. - *answers *B. the evaporator has a
pressure drop that causes more than a 2°F change in saturation
