NATE A/C EXAM 1 STUDY GUIDE LATEST VERSION / COMPLETE
REAL EXAM QUESTIONS AND CORRECT ANSWERS / A GRADE
SCORE SOLUTION.
A double suction riser is used to
A: Help improve refrigerant return
B: Allow the compressor to pump at a greater capacity
C: Decrease suction line resistance
D: Improve oil return as system capacity changes - ANSWER-D:
Improve oil return as system capacity changes
The factor determining the correct quantity of air for each room in
a building is
A: The calculated heat load for each room
B: The size of the room
C: The size of the ducts
,D: The customer's preference - ANSWER-A: The calculated heat
load for each room
Refrigerant 22 is classified as an
A: A1 refrigerant
B: A2 refrigerant
C: B1 refrigerant
D: B2 refrigerant - ANSWER-A: A1 refrigerant
ANSI/ASHRAE 34 published in 2001 and entitled "Designation and
Safety Classification of Refrigerants".
• Class A signifies refrigerants for which toxicity has not been
identified at concentrations less than or equal to 400 ppm;
• Class B signifies refrigerants for which there is evidence of
toxicity at concentrations below 400 ppm.
• Class 1 indicates refrigerants that do not show flame
propagation when tested in air at 21°C and 101 kPa;
• Class 2 indicates refrigerants having a lower flammability
limit of more than 0.10 kg/m3 at 21°C and 101 kPa and a heat of
combustion of less than 19 kJ/kg; • Class 3 indicates refrigerants
that are highly flammable as defined by a lower flammability limit
, of less than or equal to 0.10 kg/m3 at 21°C and 101 kPa or a heat
of combustion greater than or equal to 19 kJ/kg.
Which of the following combinations of instruments can be used
to measure airflow in cfm on an electric furnace?
A: A thermometer, ammeter and voltmeter
B: A thermometer, tachometer and voltmeter
C: A tachometer, pitot tube and ammeter
D: A gauge manifold set, thermometer and voltmeter - ANSWER-
A: A thermometer, ammeter and voltmeter
1. Take the temperature difference (TD) across the furnace.
2. Measure the amp draw of the electric heaters only, and the
applied voltage.
3. Determine the Kw output of the electric heaters (Kw = (A x V) /
1000
4. Determine the total output in btuh (btuh = Kw x 3415
5. Determine the cfm of the furnace with the formula: (cfm = btuh /
(1.08 x TD) Example: TD = 25deg F; (Kw = 22a x 230v = 5060 /
1000 = 5.06Kw); (btuh = 5.06 x 3415 = 17,279.9); (cfm =
REAL EXAM QUESTIONS AND CORRECT ANSWERS / A GRADE
SCORE SOLUTION.
A double suction riser is used to
A: Help improve refrigerant return
B: Allow the compressor to pump at a greater capacity
C: Decrease suction line resistance
D: Improve oil return as system capacity changes - ANSWER-D:
Improve oil return as system capacity changes
The factor determining the correct quantity of air for each room in
a building is
A: The calculated heat load for each room
B: The size of the room
C: The size of the ducts
,D: The customer's preference - ANSWER-A: The calculated heat
load for each room
Refrigerant 22 is classified as an
A: A1 refrigerant
B: A2 refrigerant
C: B1 refrigerant
D: B2 refrigerant - ANSWER-A: A1 refrigerant
ANSI/ASHRAE 34 published in 2001 and entitled "Designation and
Safety Classification of Refrigerants".
• Class A signifies refrigerants for which toxicity has not been
identified at concentrations less than or equal to 400 ppm;
• Class B signifies refrigerants for which there is evidence of
toxicity at concentrations below 400 ppm.
• Class 1 indicates refrigerants that do not show flame
propagation when tested in air at 21°C and 101 kPa;
• Class 2 indicates refrigerants having a lower flammability
limit of more than 0.10 kg/m3 at 21°C and 101 kPa and a heat of
combustion of less than 19 kJ/kg; • Class 3 indicates refrigerants
that are highly flammable as defined by a lower flammability limit
, of less than or equal to 0.10 kg/m3 at 21°C and 101 kPa or a heat
of combustion greater than or equal to 19 kJ/kg.
Which of the following combinations of instruments can be used
to measure airflow in cfm on an electric furnace?
A: A thermometer, ammeter and voltmeter
B: A thermometer, tachometer and voltmeter
C: A tachometer, pitot tube and ammeter
D: A gauge manifold set, thermometer and voltmeter - ANSWER-
A: A thermometer, ammeter and voltmeter
1. Take the temperature difference (TD) across the furnace.
2. Measure the amp draw of the electric heaters only, and the
applied voltage.
3. Determine the Kw output of the electric heaters (Kw = (A x V) /
1000
4. Determine the total output in btuh (btuh = Kw x 3415
5. Determine the cfm of the furnace with the formula: (cfm = btuh /
(1.08 x TD) Example: TD = 25deg F; (Kw = 22a x 230v = 5060 /
1000 = 5.06Kw); (btuh = 5.06 x 3415 = 17,279.9); (cfm =
