©THEBRIGHT EXAM STUDY SOLUTIONS 8/21/2024 1:28 PM
NATE Light Commercial Exam Questions
With Correct Answers
Which of the following measurements would be needed to determine oil furnace combustion
efficiency?
a. net stack temperature and CO2 concentration
b. net stack temperature and CO concentration
c. stack temperature and indoor temperature
d. stack temperature and fuel pressure - answer✔✔a. net stack temperature and CO2
concentration
When combustion is being tested on an oil furnace, high level of smoke and can be corrected by:
a. Adjusting the barometric damper.
b. Opening the air shutter.
c. Adjusting the primary control.
d. Closing the air shutter. - answer✔✔b. Opening the air shutter
A common problem with restaurant units is their location near kitchen exhaust. This could cause
high discharge pressure in the cooling mode because:
a. Return air filter becomes plugged.
b. Grease plugs the evaporator.
c. Grease plugs the condensate line.
d. Grease plugs the condenser coil. - answer✔✔d. Grease plugs the condenser coil.
,©THEBRIGHT EXAM STUDY SOLUTIONS 8/21/2024 1:28 PM
When a heat pump is in the cooling mode of operation, the check valve at the indoor coil should
be:
a. Modulating.
b. Half open.
c. Fully closed.
d. Fully open. - answer✔✔c. Fully closed.
The technician make a service call in answer to a complaint of little or no cooling from an R-22
rooftop air conditioning unit. Upon checking pressures when the unit is running, the technician
finds:
· Suction pressure 48 psig
· Discharge pressure 190 psig
· Superheat 0°F
The problem most likely occurs because the:
a. Evaporator coil is iced up.
b. Unit is full of non-condensables.
c. Dirty condenser coil.
d. Unit is overcharged. - answer✔✔a. Evaporator coil is iced up.
The result of properly converting a natural gas furnace to LP using the factory kit will:
a. Decrease the pressure and the orifice size
b. Decrease the pressure and increase the orifice size
c. increase the pressure and the orifice size
d. increase the pressure and decrease the orifice size - answer✔✔d. increase the pressure and
decrease the orifice size
At least 24 hours before you start up a system that has been shut down for a long time, you must
energize the crankcase heater, in order to:
, ©THEBRIGHT EXAM STUDY SOLUTIONS 8/21/2024 1:28 PM
a. reduce the viscosity of the oil
b. reduce the amount of refrigerant that may be in the compressor
c. warm the compressor so that it will work more efficiently
d. heat the refrigerant so that it will work more efficiently - answer✔✔b. reduce the amount of
refrigerant that may be in the compressor
In checking a restaurant, a technician find difficulty in opening the front doors. Providing that
kitchen exhaust and make-up air are balanced properly, which of the following adjustments
should be made?
a. the blower speed should be decreased
b. System BTU capacity should be increased
c. The space temperature set point should be increased
d. The minimum outdoor air setting should be checked - answer✔✔d. The minimum outdoor air
setting should be checked
A furnace is rated at 120,000 Btu input, but produces 100,000 Btu output. The percentage that
exists as lost heat is:
a. 12%
b. 17%
c. 22%
d. 20% - answer✔✔b. 17%
Air that is pre-mixed with the gas in the burner is called:
a. primary air
b. dilution air
c. secondary air
d. supply air - answer✔✔a. primary air
Velocity pressure is computed by subtracting the static pressure from the:
NATE Light Commercial Exam Questions
With Correct Answers
Which of the following measurements would be needed to determine oil furnace combustion
efficiency?
a. net stack temperature and CO2 concentration
b. net stack temperature and CO concentration
c. stack temperature and indoor temperature
d. stack temperature and fuel pressure - answer✔✔a. net stack temperature and CO2
concentration
When combustion is being tested on an oil furnace, high level of smoke and can be corrected by:
a. Adjusting the barometric damper.
b. Opening the air shutter.
c. Adjusting the primary control.
d. Closing the air shutter. - answer✔✔b. Opening the air shutter
A common problem with restaurant units is their location near kitchen exhaust. This could cause
high discharge pressure in the cooling mode because:
a. Return air filter becomes plugged.
b. Grease plugs the evaporator.
c. Grease plugs the condensate line.
d. Grease plugs the condenser coil. - answer✔✔d. Grease plugs the condenser coil.
,©THEBRIGHT EXAM STUDY SOLUTIONS 8/21/2024 1:28 PM
When a heat pump is in the cooling mode of operation, the check valve at the indoor coil should
be:
a. Modulating.
b. Half open.
c. Fully closed.
d. Fully open. - answer✔✔c. Fully closed.
The technician make a service call in answer to a complaint of little or no cooling from an R-22
rooftop air conditioning unit. Upon checking pressures when the unit is running, the technician
finds:
· Suction pressure 48 psig
· Discharge pressure 190 psig
· Superheat 0°F
The problem most likely occurs because the:
a. Evaporator coil is iced up.
b. Unit is full of non-condensables.
c. Dirty condenser coil.
d. Unit is overcharged. - answer✔✔a. Evaporator coil is iced up.
The result of properly converting a natural gas furnace to LP using the factory kit will:
a. Decrease the pressure and the orifice size
b. Decrease the pressure and increase the orifice size
c. increase the pressure and the orifice size
d. increase the pressure and decrease the orifice size - answer✔✔d. increase the pressure and
decrease the orifice size
At least 24 hours before you start up a system that has been shut down for a long time, you must
energize the crankcase heater, in order to:
, ©THEBRIGHT EXAM STUDY SOLUTIONS 8/21/2024 1:28 PM
a. reduce the viscosity of the oil
b. reduce the amount of refrigerant that may be in the compressor
c. warm the compressor so that it will work more efficiently
d. heat the refrigerant so that it will work more efficiently - answer✔✔b. reduce the amount of
refrigerant that may be in the compressor
In checking a restaurant, a technician find difficulty in opening the front doors. Providing that
kitchen exhaust and make-up air are balanced properly, which of the following adjustments
should be made?
a. the blower speed should be decreased
b. System BTU capacity should be increased
c. The space temperature set point should be increased
d. The minimum outdoor air setting should be checked - answer✔✔d. The minimum outdoor air
setting should be checked
A furnace is rated at 120,000 Btu input, but produces 100,000 Btu output. The percentage that
exists as lost heat is:
a. 12%
b. 17%
c. 22%
d. 20% - answer✔✔b. 17%
Air that is pre-mixed with the gas in the burner is called:
a. primary air
b. dilution air
c. secondary air
d. supply air - answer✔✔a. primary air
Velocity pressure is computed by subtracting the static pressure from the:
