Commercial Refrigeration Certification
In a dry type (direct expansion) evaporator, liquid refrigerant must boil away as close to
the end of the coil as possible in order to:
A. operate at high efficiency.
B. ensure that frost does not accumulate.
C. sub-cool the compressor.
D. ensure proper oil return. - *answers *A. operate at high efficiency.
The difference between the temperature of the refrigerant boiling in the evaporator and
the temperature at the evaporator outlet is known as:
A. evaporator superheat.
B. latent heat.
C. evaporator sub-cooling.
D. sublimation. - *answers *A. evaporator superheat.
An expansion device that is stuck open will cause:
A. low suction pressure
B. a starved evaporator.
C. excessive superheat
D. a flooded evaporator - *answers *D. a flooded evaporator
When measuring evaporator superheat on a commercial system that has a long suction
line, the pressure reading should be taken at the:
A. compressor inlet.
B. evaporator outlet.
C. condenser outlet.
D. receiver Inlet. - *answers *A. compressor inlet. (Suction Line)
Superheat measurements are best taken:
A. during a hot pull down.
B. at 8°F to 12°F.
C. during defrost.
D. with the system operating at design conditions. - *answers *D. with the system
operating at design conditions.
A technician is checking the superheat on a multi circuit evaporator and finds one of the
circuits has a superheat that is higher than the others. This could be caused by:
A. a dirty coil.
B. a refrigerant overcharge
C. uneven air distribution.
D. a blocked distributor. - *answers *D. a blocked distributor.
A TEV with an external equalizer is used on:
A. evaporators with a high pressure drop.
B. evaporators with a low pressure drop.
C. high temperature applications only.
D. all evaporators. - *answers *A. evaporators with a high pressure drop.
,Commercial Refrigeration Certification
Dry type evaporators operate most efficiently with a superheat setting of approximately:
A. 8° F to 12°F
B. 13° F to 19°F
C. 20° F to 30°F
D. 31° F to 40° F - *answers *A. 8° F to 12°F
An evaporator used to chill liquids in operating with a normal superheat setting, but the
system is not cooling the product properly. Which of the following is the most likely
cause?
A. overcharge of refrigerant
B. undercharge of refrigerant
C. the circulator
D. the TEV - *answers *C. the circulator
What time interval is required between each superheat adjustment?
A. Not less than 1 hour
B. About 10-15 minutes
C. At least 1/2 hour.
D. No time delay. - *answers *B. About 10-15 minutes
A low temperature evaporator used for cooling space or product refrigeration:
A. is the same as one used for medium or high temperatures.
B. must have fins spaced closer together.
C. must be frosted periodically.
D. must be defrosted periodically. - *answers *D. must be defrosted periodically.
Some special applications use a flooded evaporator (operated full of refrigerant). In
order to maintain the proper level of liquid refrigerant, a ____ type metering device is
used.
A. TEV
B. capillary tube
C. AEV
D. float - *answers *D. float
A properly functioning condenser will first:
A. condense then de-superheat.
B. subcool then de-superheat.
C. subcool then superheat.
D. de-superheat then subcool. - *answers *D. de-superheat then subcool.
Tube within a tube, shell and coil, and shell and tube are all types of:
A. water cooled condensers.
B. air cooled condensers.
C. receivers.
D. accumulators. - *answers *A. water cooled condensers.
, Commercial Refrigeration Certification
The refrigerant condensing temperature in a water cooled condenser is normally about
____ higher than the leaving water.
A. 100°F
B. 10°F
C. 30°F
D. 75°F - *answers *B. 10°F
The refrigerant in an air cooled condenser will normally condense at approximately
_____ higher temperature than the air passing over it.
A. 10°F
B. 30°F
C. 75°F
D. 100°F - *answers *B. 30°F
Workable head pressure during periods of low ambient temperature can be achieved by
using:
A. an economizer
B. evaporator dampers
C. evaporator flooding
D. fan-cycle control - *answers *D. fan-cycle control
Cooling towers that pass air over water to remove system heat are limited in capacity
by:
A. outside air wet bulb temperature.
B. outside air dry bulb temperature
C. inside air wet bulb temperature.
D. inside air dry bulb temperature. - *answers *A. outside air wet bulb temperature.
One of the main reasons that reciprocating compressors are not 100% efficient is:
A. CFC refrigerants.
B. clearance volume.
C. evaporator design
D. condenser design. - *answers *B. clearance volume.
An open drive compressor is most likely to develop a refrigerant leak at the:
A. valve plate.
B. suction service valve.
C. discharge service valve.
D. shaft seal. - *answers *D. shaft seal.
Multiple compressors provide:
A. positive on return.
B. lower humidity in high humidity locales.
C. capacity control
D. zone control. - *answers *C. capacity control
In a dry type (direct expansion) evaporator, liquid refrigerant must boil away as close to
the end of the coil as possible in order to:
A. operate at high efficiency.
B. ensure that frost does not accumulate.
C. sub-cool the compressor.
D. ensure proper oil return. - *answers *A. operate at high efficiency.
The difference between the temperature of the refrigerant boiling in the evaporator and
the temperature at the evaporator outlet is known as:
A. evaporator superheat.
B. latent heat.
C. evaporator sub-cooling.
D. sublimation. - *answers *A. evaporator superheat.
An expansion device that is stuck open will cause:
A. low suction pressure
B. a starved evaporator.
C. excessive superheat
D. a flooded evaporator - *answers *D. a flooded evaporator
When measuring evaporator superheat on a commercial system that has a long suction
line, the pressure reading should be taken at the:
A. compressor inlet.
B. evaporator outlet.
C. condenser outlet.
D. receiver Inlet. - *answers *A. compressor inlet. (Suction Line)
Superheat measurements are best taken:
A. during a hot pull down.
B. at 8°F to 12°F.
C. during defrost.
D. with the system operating at design conditions. - *answers *D. with the system
operating at design conditions.
A technician is checking the superheat on a multi circuit evaporator and finds one of the
circuits has a superheat that is higher than the others. This could be caused by:
A. a dirty coil.
B. a refrigerant overcharge
C. uneven air distribution.
D. a blocked distributor. - *answers *D. a blocked distributor.
A TEV with an external equalizer is used on:
A. evaporators with a high pressure drop.
B. evaporators with a low pressure drop.
C. high temperature applications only.
D. all evaporators. - *answers *A. evaporators with a high pressure drop.
,Commercial Refrigeration Certification
Dry type evaporators operate most efficiently with a superheat setting of approximately:
A. 8° F to 12°F
B. 13° F to 19°F
C. 20° F to 30°F
D. 31° F to 40° F - *answers *A. 8° F to 12°F
An evaporator used to chill liquids in operating with a normal superheat setting, but the
system is not cooling the product properly. Which of the following is the most likely
cause?
A. overcharge of refrigerant
B. undercharge of refrigerant
C. the circulator
D. the TEV - *answers *C. the circulator
What time interval is required between each superheat adjustment?
A. Not less than 1 hour
B. About 10-15 minutes
C. At least 1/2 hour.
D. No time delay. - *answers *B. About 10-15 minutes
A low temperature evaporator used for cooling space or product refrigeration:
A. is the same as one used for medium or high temperatures.
B. must have fins spaced closer together.
C. must be frosted periodically.
D. must be defrosted periodically. - *answers *D. must be defrosted periodically.
Some special applications use a flooded evaporator (operated full of refrigerant). In
order to maintain the proper level of liquid refrigerant, a ____ type metering device is
used.
A. TEV
B. capillary tube
C. AEV
D. float - *answers *D. float
A properly functioning condenser will first:
A. condense then de-superheat.
B. subcool then de-superheat.
C. subcool then superheat.
D. de-superheat then subcool. - *answers *D. de-superheat then subcool.
Tube within a tube, shell and coil, and shell and tube are all types of:
A. water cooled condensers.
B. air cooled condensers.
C. receivers.
D. accumulators. - *answers *A. water cooled condensers.
, Commercial Refrigeration Certification
The refrigerant condensing temperature in a water cooled condenser is normally about
____ higher than the leaving water.
A. 100°F
B. 10°F
C. 30°F
D. 75°F - *answers *B. 10°F
The refrigerant in an air cooled condenser will normally condense at approximately
_____ higher temperature than the air passing over it.
A. 10°F
B. 30°F
C. 75°F
D. 100°F - *answers *B. 30°F
Workable head pressure during periods of low ambient temperature can be achieved by
using:
A. an economizer
B. evaporator dampers
C. evaporator flooding
D. fan-cycle control - *answers *D. fan-cycle control
Cooling towers that pass air over water to remove system heat are limited in capacity
by:
A. outside air wet bulb temperature.
B. outside air dry bulb temperature
C. inside air wet bulb temperature.
D. inside air dry bulb temperature. - *answers *A. outside air wet bulb temperature.
One of the main reasons that reciprocating compressors are not 100% efficient is:
A. CFC refrigerants.
B. clearance volume.
C. evaporator design
D. condenser design. - *answers *B. clearance volume.
An open drive compressor is most likely to develop a refrigerant leak at the:
A. valve plate.
B. suction service valve.
C. discharge service valve.
D. shaft seal. - *answers *D. shaft seal.
Multiple compressors provide:
A. positive on return.
B. lower humidity in high humidity locales.
C. capacity control
D. zone control. - *answers *C. capacity control
