HVAC NATE Heat Pump/ 171 Q&A/ Already Graded A+ Terms like:
A resistance reading of infinity across the "R" terminal and "S" terminal of a compressor motor indicates a(n) _________. - Answer: open motor winding
An acceptable capacitance reading for a run capacitor is _____ the microfarad
r...
HVAC NATE Heat Pump/ 171 Q&A/ Already
Graded A+
A resistance reading of infinity across the "R" terminal and "S" terminal of a compressor motor
indicates a(n) _________. - Answer: open motor winding
An acceptable capacitance reading for a run capacitor is _____ the microfarad
rating printed on the capacitor. - Answer: plus or minus 10% of.
How may CFM per ton of cooling? - Answer: 400CFM per ton
How many BTUh per ton of cooling? - Answer: 12,000BTUH per ton
What is measured to determine the total resistance to
airflow in a ductwork system? - Answer: External static pressure at the air handler or furnace
What is the output of a residential electric furnace when the voltage impressed is equal to 235
V and its current draw is 40 A? - Answer: 32,080 Btuh
Page 1 of 21
,Btuh = W x 3.413
W=VxA
What is the total CFM:
Voltage: 240V
Amps: 40A
Return air: 70
Supply air: 105 - Answer: 867 cfm
cfm = (voltage x current x 3.413) / (temperature rise x 1.08)
What is the recommended face velocity for air leaving a supply register? - Answer: 700 ft/min
Temperature readings taken 6 in. from the compressor discharge line should never exceed
___________ F. - Answer: 225°F
A system should operate at least _____ before heat measurements are taken - Answer: 20
minutes
What gas should be purged through a refrigerant circuit to prevent the formation of oxides
whenever brazing is being done? - Answer: Dry Nitrogen
What certification is required before a technician is permitted to work on air conditioning and
heat pump systems? - Answer: EPA Section 608 certification
On an R-22 system, line diameters and lengths are typically specified for a vapor pressure drop
that does not exceed what? - Answer: 6-7PSI or 6F
Page 2 of 21
, What is the primary purpose of using flux when soldering copper or brass parts? - Answer:
Prevent Oxidation
The water that results from a defrost cycle of an air-to-air heat pump(runoff) must? - Answer:
Drain off and away from the outdoor coil.
Why must the runoff be drained o/'ff and away from the outdoor coil? - Answer: Excessive ice
can build up on the bottom of the coil and can reduce capacity.
What is the component that reduces sound transmission and prevents water leaks of a package
heat pump installed on a roof? - Answer: Curb Gasket
Why do you need to add a control for a heat pump indoor coil that is installed on a fossil fuel
furnace? - Answer: So the heat pump and furnace do not operate at the same time in normal
heating.
What happens when you energize a hermetic refrigeration compressor and the system is in a
deep vacuum? - Answer: Motor windings could become damaged.
What needs to happen in order to consider an evacuation to be complete? - Answer: System
should be evacuated to a vacuum of 500 Microns or below.
A system is supplied from the factory with charge for a 15 foot line set. The data plate shows the
required system charge to be 5 pounds 10 ounces. The line set uses a 3/8 inch liquid line and is
25 feet long. The manufacturer's instruction sheet specifies 0.6 ounces of refrigerant to be
added for each added foot of refrigerant line length. How much refrigerant is needed to
completely charge the system? - Answer: 6lbs
Page 3 of 21
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