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HVAC NATE Heat Pump/ 171 Q&A/ Already Graded A+

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HVAC NATE Heat Pump/ 171 Q&A/ Already Graded A+ Terms like: What is the absolute pressure at sea level if a gauge pressure is 35 psig? - Answer: 49.7psia 100,000 BTUH output furnace. Return air temp is 65F. Supply air is 135F. What is the CFM? - Answer: 1323CFM What is the best method ...

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  • October 21, 2024
  • 21
  • 2024/2025
  • Exam (elaborations)
  • Questions & answers

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  • HVAC NATE Heat Pump
  • HVAC NATE Heat Pump

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HVAC NATE Heat Pump/ 171 Q&A/ Already
Graded A+
What is the absolute pressure at sea level if a gauge pressure is 35 psig? - Answer: 49.7psia


100,000 BTUH output furnace.
Return air temp is 65F.
Supply air is 135F.
What is the CFM? - Answer: 1323CFM


What is the best method of repair when a residential supply diffuser is noisy because of a loose
vane? - Answer: Replace the diffuser.


When performing preventive maintenance on a heat pump what should the technician check
and why? - Answer: Outdoor fan. To be certain it runs freely with no binding.


What is the effect of 170 volts supplied to a 208/230 volt compressor? - Answer: Would cause
the current to increase and the motor may trip on overload.



Page 1 of 21

,On a service call for a cooling problem with a heat pump, your inspections find a liquid line that
has condensation on it. What is most likely to cause this? - Answer: Restriction in the liquid line.


What is a reason for cool air complaints when a heat pump is operating in the heating cycle? -
Answer: Excessive supply air velocities.


The following measurements are recorded on an operating heat pump system. The heat pump
is operating with the compressor only with no auxiliary heat:


• Heat pump only supply air temperature 92°F


• Heat pump only return air temperature 70°F


• Outdoor temperature 54°F


• Supply air temp. /auxiliary heat ON 115°F


• Return air temp. /auxiliary heat ON 70°F


• CFM 1228


What is the heating capacity in BTUH? - Answer: 29,177 BTU/H


Inadequate heating can be caused by what? - Answer: Dirty or clogged air filter.


To minimize noise problems in residential duct systems, what is the range (recommended to
maximum) of design air velocity in the rectangular main supply trunk? - Answer: 700 to 900 fpm


conditions while checking a packaged heat pump in cooling.


Page 2 of 21

, • The unit has a piston type metering device on both the indoor and outdoor coils.


• Outdoor temperature 75°F


• Superheat 55°F


What is wrong with the system? - Answer: Undercharged.


What will you get when a capillary tube is overcharged? - Answer: low superheat and high sub
cooling


What is the effect of a low charge on the switchover operations of a reversing valve? - Answer:
Reversing valves are less likely to transfer if charge is low.


A technician is working on a heat pump with a capacitor start-capacitor run compressor. On
initial startup, the compressor hums momentarily and the shuts down on internal overload.
What is the problem? - Answer: Too great a pressure difference on the compressor.


A step down transformer has a rating of 40 VA. Its primary voltage is 120V with a secondary
voltage of 24V. What is the maximum current draw of a load connected to this transformer? -
Answer: 1.7amps


What does a bright red or orange glow from the resistance element in a duct heater indicate? -
Answer: Flow of air is insufficient.


What does the outdoor fan do during defrost on a heat pump and why? - Answer: The fan stops
to minimize defrost time.




Page 3 of 21

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