HVAC NATE HEAT PUMP EXAM
Questions and Answers
1.On an R-22 system, line diameters and lengths are typically
specified for a vapor pressure drop that does not exceed what?
ANS 6-7PSI or 6F
2.What is the primary purpose of using flux when soldering
copper or brass parts?
ANS Prevent Oxidation
3.The water that results from a defrost cycle of an air to air
heat pump(runoff) must?
ANS Drain off and away from the outdoor coil.
4.Why must the runoff be drained off and away from the
outdoor coil?
ANS Exces- sive ice can build up on the bottom of the coil and can
reduce capacity.
5.What is the component that reduces sound transmission
and prevents water leaks of a package heat pump installed
on a roof?
ANS Curb Gasket
,6.Why do you need to add a control for a heat pump indoor coil
that is installed on a fossil fuel furnace?
ANS So the heat pump and furnace do not operate at the same time in
normal heating.
7.What happens when you energize a hermetic refrigeration
compressor and the system is in a deep vacuum?
ANS Motor windings could become damaged.
8.What needs to happen in order to consider an evacuation to be
complete?-
ANS System should be evacuated to a vacuum of 500 Microns or below.
9.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?
ANS 6lbs
10.Where are drive slips typically installed?
,ANS On the shorter sides of rectangular duct.
11.What is a necessary check to properly set a heat
anticipator?
ANS Heating control circuit amperage
draw.
12.A heat pump operating in normal ice free conditions
maintains a certain temperature difference between the
outdoor coil temperature and the sur- rounding outdoor
ambient. What is this temperature referred to as?
ANS Coil TD.
13.What is the smallest refrigerant leak that an electronic leak
detector should be capable of sensing?
ANS .o5oz per year.
14.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?
ANS No
15.What is the absolute pressure at sea level if a gauge
pressure is 35 psig?
ANS 49.7psia
, 16.100,000 BTUH output
furnace. Return air temp is
65F.
Supply air is 135F.
What is the CFM?
ANS 1323CFM
17.What is the best method of repair when a residential
supply diffuser is noisy because of a loose vane?
ANS Replace the diffuser.
18.When performing preventive maintenance on a heat pump
what should the technician check and why?
ANS Outdoor fan. To be certain it runs freely with no binding.
19.What is the effect of 170 volts supplied to a 208/230 volt
compressor?
ANS -
Would cause the current to increase and the motor may trip on overload.
20.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?
ANS Restriction in the liquid line.
Questions and Answers
1.On an R-22 system, line diameters and lengths are typically
specified for a vapor pressure drop that does not exceed what?
ANS 6-7PSI or 6F
2.What is the primary purpose of using flux when soldering
copper or brass parts?
ANS Prevent Oxidation
3.The water that results from a defrost cycle of an air to air
heat pump(runoff) must?
ANS Drain off and away from the outdoor coil.
4.Why must the runoff be drained off and away from the
outdoor coil?
ANS Exces- sive ice can build up on the bottom of the coil and can
reduce capacity.
5.What is the component that reduces sound transmission
and prevents water leaks of a package heat pump installed
on a roof?
ANS Curb Gasket
,6.Why do you need to add a control for a heat pump indoor coil
that is installed on a fossil fuel furnace?
ANS So the heat pump and furnace do not operate at the same time in
normal heating.
7.What happens when you energize a hermetic refrigeration
compressor and the system is in a deep vacuum?
ANS Motor windings could become damaged.
8.What needs to happen in order to consider an evacuation to be
complete?-
ANS System should be evacuated to a vacuum of 500 Microns or below.
9.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?
ANS 6lbs
10.Where are drive slips typically installed?
,ANS On the shorter sides of rectangular duct.
11.What is a necessary check to properly set a heat
anticipator?
ANS Heating control circuit amperage
draw.
12.A heat pump operating in normal ice free conditions
maintains a certain temperature difference between the
outdoor coil temperature and the sur- rounding outdoor
ambient. What is this temperature referred to as?
ANS Coil TD.
13.What is the smallest refrigerant leak that an electronic leak
detector should be capable of sensing?
ANS .o5oz per year.
14.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?
ANS No
15.What is the absolute pressure at sea level if a gauge
pressure is 35 psig?
ANS 49.7psia
, 16.100,000 BTUH output
furnace. Return air temp is
65F.
Supply air is 135F.
What is the CFM?
ANS 1323CFM
17.What is the best method of repair when a residential
supply diffuser is noisy because of a loose vane?
ANS Replace the diffuser.
18.When performing preventive maintenance on a heat pump
what should the technician check and why?
ANS Outdoor fan. To be certain it runs freely with no binding.
19.What is the effect of 170 volts supplied to a 208/230 volt
compressor?
ANS -
Would cause the current to increase and the motor may trip on overload.
20.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?
ANS Restriction in the liquid line.
