HVAC NATE Heat Pump Questions and
Answers with Certified Solutions
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
Answers with Certified Solutions
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
