HVAC NATE Heat Pump
Exam/171 Questions and
Correct Answers/Updated
On an R-22 system, line diameters and lengths are typically specified for
a vapor pressure drop that does not exceed what? - -6-7PSI or 6F
-What is the primary purpose of using flux when soldering copper or
brass parts? - -Prevent Oxidation
-The water that results from a defrost cycle of an air to air heat
pump(runoff) must? - -Drain off and away from the outdoor coil.
-Why must the runoff be drained off and away from the outdoor coil? - -
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? - -Curb Gasket
-Why do you need to add a control for a heat pump indoor coil that is
installed on a fossil fuel furnace? - -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? - -Motor windings could become
damaged.
-What needs to happen in order to consider an evacuation to be
complete? - -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? - -6lbs
-Where are drive slips typically installed? - -On the shorter sides of
rectangular duct.
-What is a necessary check to properly set a heat anticipator? - -Heating
control circuit amperage
draw.
, -A heat pump operating in normal ice free conditions maintains a certain
temperature difference between the outdoor coil temperature and the
surrounding outdoor ambient. What is this temperature referred to as? -
-Coil TD.
-What is the smallest refrigerant leak that an electronic leak detector
should be capable of sensing? - -.o5oz per year.
-When checking the pressures in an operating system with a manifold
gauge set, will refrigerant oil in a hose will have an effect on the gauge?
- -No
-What is the absolute pressure at sea level if a gauge pressure is 35
psig? - -49.7psia
-100,000 BTUH output furnace.
Return air temp is 65F.
Supply air is 135F.
What is the CFM? - -1323CFM
-What is the best method of repair when a residential supply diffuser is
noisy because of a loose vane? - -Replace the diffuser.
-When performing preventive maintenance on a heat pump what should
the technician check and why? - -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? -
-Would cause the current to increase and the motor may trip on
overload.
-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? - -Restriction in the liquid line.
-What is a reason for cool air complaints when a heat pump is operating
in the heating cycle? - -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
Exam/171 Questions and
Correct Answers/Updated
On an R-22 system, line diameters and lengths are typically specified for
a vapor pressure drop that does not exceed what? - -6-7PSI or 6F
-What is the primary purpose of using flux when soldering copper or
brass parts? - -Prevent Oxidation
-The water that results from a defrost cycle of an air to air heat
pump(runoff) must? - -Drain off and away from the outdoor coil.
-Why must the runoff be drained off and away from the outdoor coil? - -
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? - -Curb Gasket
-Why do you need to add a control for a heat pump indoor coil that is
installed on a fossil fuel furnace? - -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? - -Motor windings could become
damaged.
-What needs to happen in order to consider an evacuation to be
complete? - -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? - -6lbs
-Where are drive slips typically installed? - -On the shorter sides of
rectangular duct.
-What is a necessary check to properly set a heat anticipator? - -Heating
control circuit amperage
draw.
, -A heat pump operating in normal ice free conditions maintains a certain
temperature difference between the outdoor coil temperature and the
surrounding outdoor ambient. What is this temperature referred to as? -
-Coil TD.
-What is the smallest refrigerant leak that an electronic leak detector
should be capable of sensing? - -.o5oz per year.
-When checking the pressures in an operating system with a manifold
gauge set, will refrigerant oil in a hose will have an effect on the gauge?
- -No
-What is the absolute pressure at sea level if a gauge pressure is 35
psig? - -49.7psia
-100,000 BTUH output furnace.
Return air temp is 65F.
Supply air is 135F.
What is the CFM? - -1323CFM
-What is the best method of repair when a residential supply diffuser is
noisy because of a loose vane? - -Replace the diffuser.
-When performing preventive maintenance on a heat pump what should
the technician check and why? - -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? -
-Would cause the current to increase and the motor may trip on
overload.
-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? - -Restriction in the liquid line.
-What is a reason for cool air complaints when a heat pump is operating
in the heating cycle? - -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
