HVAC Midterm Exam with All Correct & 100% Verified
Answers| Actual Complete Exam |Already Graded A+
One watt (1 W) of electrical energy is equivalent to ________ Btu's of heat energy. ✔Correct
Answer-3.413 Btus
Latent heat is also know as.
A. Heat quantity
B. Heat Intensity
C. Hidden Heat
D. Specific Heat ✔Correct Answer-C. Hidden Heat
What is superheat?
A. A vapor with a temperature above its saturation temperature.
B. The temperature of refrigerant leaving the evaporator
C. The temperature of refrigerant entering the compressor.
D. None of the above ✔Correct Answer-A. A vapor with a temperature above its saturation
temperature.
The indoor coil of a heat pump system serves as the _____ during the cooling season, and as the
_____ during the heating season. ✔Correct Answer-evaporator, condenser
In which component of a refrigeration system is heat removed? ✔Correct Answer-The Condenser
What is the most common type of heat pump used in residential applications? ✔Correct Answer-
Air-to-air split system
What indoor air volume (expressed in cfm) would be required for a heating unit that has a 50°F
temperature rise and an output of 80,000 Btuh?
* See formula page ✔Correct Answer-1481 cfm
How much auxiliary heat will be required on a design day when a home's heat loss is 35,600 Btuh
and the heat pump output is 17,200 Btuh?
* See formula page ✔Correct Answer-5.39 kW or 5,390 watts
Why does the indoor coil of a heat pump need more area than the indoor coil of a cooling-only unit?
✔Correct Answer-To prevent the condensing temperatures and corresponding head pressures from
becoming too high during the heating cycle.
Why does a heat pump require three-function control? ✔Correct Answer-Because a heat pump
performs three functions-it provides cooling, it provides heating, and it must defrost the outdoor coil
when ice forms on it.
, What is the coefficient of performance (COP) of a heat pump? ✔Correct Answer-A comparison of
how much heat the heat pump is producing compared to how much heat an electric furnace would
produce using the same amount of electricity.
What three types of compressors are used in residential heat pump applications? ✔Correct
Answer-Reciprocating, scroll, and rotary.
Name two problems that occur when flash gas enters a TEV while a system is operating? ✔Correct
Answer-The valve operates inefficiently, the system
loses capacity, and superheat increases.
Typical superheat values measured at the evaporator outlet of a properly operating heat pump
system is about how many degrees? ✔Correct Answer-10 to 12 degrees
((Ref: 124/2))
TEVs that limit the pressure created by an expanding bulb charge are called what? ✔Correct
Answer-Maximum operating pressure (MOP)
If a system operates correctly in one cycle and pumps down when switched to the other cycle, what
problem is indicated? ✔Correct Answer-A defective TEV (in such cases, the power element could
be defective) or a stuck check valve.
How can you inspect ball-type check valves for free movement of the ball? ✔Correct Answer-
Valves of this type may be checked for free movement with a magnet when the system is not
running.
Why are suction-line accumulators used in heat pump systems? ✔Correct Answer-To protect the
compressor from liquid refrigerant.
Where in the refrigerant circuit is an accumulator located? ✔Correct Answer-Between the
reversing valve and the compressor inlet.
How does the oil return to the compressor in a heat pump system that is equipped with a suction-
line accumulator? ✔Correct Answer-Through the small hole drilled in the lower portion of the U-
tube.
Describe the method used to free up a sticky main valve slide. ✔Correct Answer-With the system
operating at normal operating pressures, rapidly energize and deenergize the reversing valve
solenoid several times. Before condemning the valve, perform the same procedure after raising the
system head pressure.
Unless otherwise noted, all wiring diagrams depict switches and contacts in what mode? ✔Correct
Answer-Deenergized
((Ref: 149/3))
A normally open contact is open when the power to the unit is on or off? ✔Correct Answer-off
((Ref: 149/3))
Answers| Actual Complete Exam |Already Graded A+
One watt (1 W) of electrical energy is equivalent to ________ Btu's of heat energy. ✔Correct
Answer-3.413 Btus
Latent heat is also know as.
A. Heat quantity
B. Heat Intensity
C. Hidden Heat
D. Specific Heat ✔Correct Answer-C. Hidden Heat
What is superheat?
A. A vapor with a temperature above its saturation temperature.
B. The temperature of refrigerant leaving the evaporator
C. The temperature of refrigerant entering the compressor.
D. None of the above ✔Correct Answer-A. A vapor with a temperature above its saturation
temperature.
The indoor coil of a heat pump system serves as the _____ during the cooling season, and as the
_____ during the heating season. ✔Correct Answer-evaporator, condenser
In which component of a refrigeration system is heat removed? ✔Correct Answer-The Condenser
What is the most common type of heat pump used in residential applications? ✔Correct Answer-
Air-to-air split system
What indoor air volume (expressed in cfm) would be required for a heating unit that has a 50°F
temperature rise and an output of 80,000 Btuh?
* See formula page ✔Correct Answer-1481 cfm
How much auxiliary heat will be required on a design day when a home's heat loss is 35,600 Btuh
and the heat pump output is 17,200 Btuh?
* See formula page ✔Correct Answer-5.39 kW or 5,390 watts
Why does the indoor coil of a heat pump need more area than the indoor coil of a cooling-only unit?
✔Correct Answer-To prevent the condensing temperatures and corresponding head pressures from
becoming too high during the heating cycle.
Why does a heat pump require three-function control? ✔Correct Answer-Because a heat pump
performs three functions-it provides cooling, it provides heating, and it must defrost the outdoor coil
when ice forms on it.
, What is the coefficient of performance (COP) of a heat pump? ✔Correct Answer-A comparison of
how much heat the heat pump is producing compared to how much heat an electric furnace would
produce using the same amount of electricity.
What three types of compressors are used in residential heat pump applications? ✔Correct
Answer-Reciprocating, scroll, and rotary.
Name two problems that occur when flash gas enters a TEV while a system is operating? ✔Correct
Answer-The valve operates inefficiently, the system
loses capacity, and superheat increases.
Typical superheat values measured at the evaporator outlet of a properly operating heat pump
system is about how many degrees? ✔Correct Answer-10 to 12 degrees
((Ref: 124/2))
TEVs that limit the pressure created by an expanding bulb charge are called what? ✔Correct
Answer-Maximum operating pressure (MOP)
If a system operates correctly in one cycle and pumps down when switched to the other cycle, what
problem is indicated? ✔Correct Answer-A defective TEV (in such cases, the power element could
be defective) or a stuck check valve.
How can you inspect ball-type check valves for free movement of the ball? ✔Correct Answer-
Valves of this type may be checked for free movement with a magnet when the system is not
running.
Why are suction-line accumulators used in heat pump systems? ✔Correct Answer-To protect the
compressor from liquid refrigerant.
Where in the refrigerant circuit is an accumulator located? ✔Correct Answer-Between the
reversing valve and the compressor inlet.
How does the oil return to the compressor in a heat pump system that is equipped with a suction-
line accumulator? ✔Correct Answer-Through the small hole drilled in the lower portion of the U-
tube.
Describe the method used to free up a sticky main valve slide. ✔Correct Answer-With the system
operating at normal operating pressures, rapidly energize and deenergize the reversing valve
solenoid several times. Before condemning the valve, perform the same procedure after raising the
system head pressure.
Unless otherwise noted, all wiring diagrams depict switches and contacts in what mode? ✔Correct
Answer-Deenergized
((Ref: 149/3))
A normally open contact is open when the power to the unit is on or off? ✔Correct Answer-off
((Ref: 149/3))
