NATE Light Commercial
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 correct answers 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. correct answers b. Opening the
air shutter
A common problem with restaurant units is their location near kitchen
exhaust.
could Thishigh discharge pressure in the cooling mode
cause
because:
a. Return air filter becomes
plugged.
b. Grease plugs the
evaporator.
c. Grease plugs the condensate
line.
d. Grease plugs the condenser coil. correct answers d. Grease plugs the
condenser
coil
.
When a heat pump is in the cooling mode of operation, the check valve at
the indoor
coil should
be:
a.
Modulating.
b. Half
c. Fully
open. .
closed
d. Fully open. correct answers c. Fully
closed.
The technician make a service call in answer to a complaint of little or no
cooling
an R-22 from
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. correct answers 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
b. size the pressure and increase the
Decrease
orifice
c. size the pressure and the
increase
orifice
d. size the pressure and decrease the orifice size correct answers d.
increase
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
you musttime,
energize the crankcase heater, in
order to:
a. reduce the viscosity of
thereduce
b. oil 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 correct answers
b. reduce
amount ofthe
refrigerant that may be in the
compressor
In checking a restaurant, a technician find difficulty in opening the front
doors.
that Providing
kitchen exhaust and make-up air are balanced properly, which of
the following should be
adjustments
made?
a. the blower speed should be
decreased
b. System BTU capacity should be
increased
c. The space temperature set point should be
d. The minimum outdoor air setting should be checked correct
increased
answers d.outdoor
minimum The air setting should be
checked
A furnace is rated at 120,000 Btu input, but produces 100,000 Btu
output. The that exists as lost
percentage
heat is:
a.
12%
b.
17%
c.
22%
d. 20% correct answers 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 correct answers a.
primary air
Velocity pressure is computed by subtracting the static pressure
from the:
a. absolute
pressure
b. gauge
pressure
c. total
pressure
d. differential pressure correct answers c. total
pressure
For a single state LP furnace, the manifold gas pressure to the
atmospheric
should burners
be a minimum
of:
a. 3.5 inches of water
b. 7 inches of water
column
column
c. 10 inches of water
column
d. 13 inches of water column correct answers c. 10 inches of
water column
With 240-volt, 60-Hz, single- phase power and a 5-kw heater, how many
amperes
be will how many BTUH of heat will be
used and
generated?
a. 10.8 amperes, providing 9,250
BTUH
b. 15.9 amperes, providing 19,576
BTUH
c. 20.8 amperes, providing 17,065
BTUH
d. 20.8 amperes, providing 14,450 BTUH correct answers c. 20.8 amperes,
providing
17,065
BTUH
While performing a maintenance check of an operating electric furnace
with
data aplate,
missing
the technician needs to determine the total kilowatt
consumption
elements. of allof the following instruments would normally be used to
Which
obtain data for
this
calculation?
a. voltmeter and
thermometer
b. ohmmeter and
voltmeter
c. ohmmeter and
ammeter
d. ammeter and voltmeter correct answers d. ammeter and
voltmeter
On a maintenance check of an electric furnace, a technician notices
deterioration
wire connectionsof the
to the elements. The most appropriate course of action is
to replace
the
:
a. wire, terminals ends, elements, and check the
amperage
b. wire and terminal ends and check the
c. fusible links, elements, and check the
amperage
amperage
d. terminal ends, elements, and check the amperage correct answers
b. wire and
terminal ends and check the
amperage
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 correct answers 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. correct answers b. Opening the
air shutter
A common problem with restaurant units is their location near kitchen
exhaust.
could Thishigh discharge pressure in the cooling mode
cause
because:
a. Return air filter becomes
plugged.
b. Grease plugs the
evaporator.
c. Grease plugs the condensate
line.
d. Grease plugs the condenser coil. correct answers d. Grease plugs the
condenser
coil
.
When a heat pump is in the cooling mode of operation, the check valve at
the indoor
coil should
be:
a.
Modulating.
b. Half
c. Fully
open. .
closed
d. Fully open. correct answers c. Fully
closed.
The technician make a service call in answer to a complaint of little or no
cooling
an R-22 from
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. correct answers 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
b. size the pressure and increase the
Decrease
orifice
c. size the pressure and the
increase
orifice
d. size the pressure and decrease the orifice size correct answers d.
increase
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
you musttime,
energize the crankcase heater, in
order to:
a. reduce the viscosity of
thereduce
b. oil 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 correct answers
b. reduce
amount ofthe
refrigerant that may be in the
compressor
In checking a restaurant, a technician find difficulty in opening the front
doors.
that Providing
kitchen exhaust and make-up air are balanced properly, which of
the following should be
adjustments
made?
a. the blower speed should be
decreased
b. System BTU capacity should be
increased
c. The space temperature set point should be
d. The minimum outdoor air setting should be checked correct
increased
answers d.outdoor
minimum The air setting should be
checked
A furnace is rated at 120,000 Btu input, but produces 100,000 Btu
output. The that exists as lost
percentage
heat is:
a.
12%
b.
17%
c.
22%
d. 20% correct answers 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 correct answers a.
primary air
Velocity pressure is computed by subtracting the static pressure
from the:
a. absolute
pressure
b. gauge
pressure
c. total
pressure
d. differential pressure correct answers c. total
pressure
For a single state LP furnace, the manifold gas pressure to the
atmospheric
should burners
be a minimum
of:
a. 3.5 inches of water
b. 7 inches of water
column
column
c. 10 inches of water
column
d. 13 inches of water column correct answers c. 10 inches of
water column
With 240-volt, 60-Hz, single- phase power and a 5-kw heater, how many
amperes
be will how many BTUH of heat will be
used and
generated?
a. 10.8 amperes, providing 9,250
BTUH
b. 15.9 amperes, providing 19,576
BTUH
c. 20.8 amperes, providing 17,065
BTUH
d. 20.8 amperes, providing 14,450 BTUH correct answers c. 20.8 amperes,
providing
17,065
BTUH
While performing a maintenance check of an operating electric furnace
with
data aplate,
missing
the technician needs to determine the total kilowatt
consumption
elements. of allof the following instruments would normally be used to
Which
obtain data for
this
calculation?
a. voltmeter and
thermometer
b. ohmmeter and
voltmeter
c. ohmmeter and
ammeter
d. ammeter and voltmeter correct answers d. ammeter and
voltmeter
On a maintenance check of an electric furnace, a technician notices
deterioration
wire connectionsof the
to the elements. The most appropriate course of action is
to replace
the
:
a. wire, terminals ends, elements, and check the
amperage
b. wire and terminal ends and check the
c. fusible links, elements, and check the
amperage
amperage
d. terminal ends, elements, and check the amperage correct answers
b. wire and
terminal ends and check the
amperage
