Heat pump exam

1. An air-to-air heat pump has many of the same components as an air conditioning system. The major difference is that a heat pump also has a (an);

C: reversing valve.

2. What is the difference between "demand defrost" and "timed defrost?"

D: Demand defrost happens only when needed and timed defrost is based on time whether it is needed or not.

3. The thermostat that controls the auxiliary electric heat according to the outdoor temperature is called the;

C: outdoor ambient thermostat.

4. The outdoor temperature at which the heat pump provides the same amount of heat as the heat loss of the conditioned space without auxiliary heat is known as the;

A: initial balance point.

5. At what temperature is an outdoor ambient thermostat normally set?

B: At or slightly above the initial balance point.

6. The outdoor coil is frozen solid on a "no heat" service call. The most likely reason is:

D: The outdoor fan is inoperative

7. In order to determine a heat pumps' balance point, you must first calculate;

A: the building's heat load.

8. Heat pumps are sized to handle the;

A: cooling load.

A high effciency heat pump system desinged to function form high to low ambient conidtions below 10 F, may have

B: two outddor coils with parallel metering devices

10. Room thermostats for heat pumps should be installed;

B: as near to the main return air grill as possible.

11. When the heat pump compressor has malfunetioned, the cus tomer has the option to switch the system into;

B: emergency heat mode.

12. Start-up with a night set back digital thermostat requires the technician to always;

B: teach the customer to program the thermostat.

13. The heat pump defrost board can be manipulated by the technician to;

C: simulate the defrost cycle.

The air-to-air heat pump outdoor unit is most efficient if located;

C: in a moderate climate zone.

15. Which of the following are are innovations that may be found on new high efficiency units?

D: ECM fan motors

16. How may a lockout (impedance) relay be reset?

C: Simply disconnect power to the unit momentarily.

17. The temperature difference between the 1st and 2nd bulbs for heating on a heat pump thermostat is;

C: approximately 2°F

18. What does the SEER rating determine?

B. Dividing the BTUs removed by the watts consumed during the cooling season

19. What might happen if the indoor fan is operated at an excessive speed in the coolin mode?

A: The system will not properly remove the humidity from the condtioned space

20. The most preferred method of charging any system in the field is;

C: by weight.

21. What is the industry standard for deep vacuum?

B: triple evacuate with nitrogen

22. Good service practice for installation of a reversing valve includes;

D: use heat paste and wet rags while brazing in the new valve.

off cycle crankcase heat is provided by

A: One leg of supply voltage is directed through the start winding.

You are checking for proper airflow in CFM on a three ton heat pump system, The systen has one return grill measuring 24×24, which has a net free area of 3.4 square feet. You measure air velcoity and calculate an average of 400 FPM. From this infomration you can conclude that

B : airflow in CFM is within normal

25. What control operates the 1't stage of secondary heat?

C: The second heating stage of the indoor thermostat.

26. What is the industry standard for maximum duration for defrost?

D: A maximum of 30 minutes.

27. What is the recommended CFM across the evaporator coil of a heat pump?

B: 400 to 450 CFM.

28. If manufacturers specifications are not available, a good way to determine cubic feet per minute through a coil is to:

A: Use temp rise of emergency heat mode

29. What type of defrost is employed on this heat pump?

B: Time and temperature initiation, time or temperature termination.

30. Which component is responsible for energizing auxiliary heat during the defrost cycle?

D: The defrost relay.

31. When this unit switches to the heat mode, describe the sequence of events that take place.

A: The RVR coil is energized through TH-1. The CR coil is energized through the RVR contacts.

32. The DTC motor and cam will close the DTC N.O. Contacts momentarily (approx 5 seconds). How is the DFR kept energized when the DTC N.O contacts open?

C : The DFR No. contacts close , which forms a holding circuit .

33. How is defrost terminated in this system?

D:Either the time or temperature termination requirements has been satisfied

34. Where is the LLP physically tapped into the system on this heat pump?

C: On the liauid line before the reversing valve

35. You are starting-up a split system heat pump for the first time. The outdoor ambien temperature is 60 ° F . You check the temperature split across the indoor coil in the heat mode and find it is 38°F. You switch to cooling mode and determine a temperature split of 29°F. The most likely corrective action (relative to airflow) is;

D: increase the outdoor fan speed.

36. Heat pump heating mode efficiency is rated in

B. HSPF

37. On a water source heat pump, the heat mode water regulating valve must be

C: reverse acting

38. An R410a heat pump operating in the heating mode has a suction pressure 50 psig and head pressure of 285 psig has a compression ratio of

C: 5.7:1

39. Which type of heat pump does not require a defrost cycle

D. Water source

40. An r-410a heat pump operating in the cooling mode has a suction pressureof 129 psig . Adding 2 psig for pressure drop in the coil, the true outlet pressure is 131 psig. The temperature of the suction line at the outlet of the evaporator is 57 F. What is the superheat

D: 12 degrees.

41. On a time initiation / temperature termination defrost, the defrost time clock has one N.O. and one N.C: switch. When do the positions of these switches change?

B. Every 30 or 90 mineutes, depesniding on the cam insalled in the timer

42. What would be the result of closing registers is rooms that are uninhabited while operating in the heating mode

D: The discharge pressure and temperature will rise decreasing the life span of the unit

43. What is the most common complaint from a customer changing from gas heat to a heat pump?

A: Cold air at high velocities coming out of the registers.

44. When a heat pump is operating in the heat mode, the suction line at the compressor will feel;

D: cold and sweaty

45. The use of a scroll type compressor on a heat pump can eliminate the need for a;

D: suction line accumulator.

46. A heat pump operates satisfactorily in the cooling mode, but not in the heat mode. This could be caused by;

D: a stuck check valve or clogged TXV screen.

47. It is not always a good idea to immediately connect a standard gauge manifold set and hoses to a heat pump when a problem is suspected because;

C: the charge is critical, sometimes to + 1/2 oz. refrigerant.

48. Which component is responsible for changing the direction of the flow of refrigerant?

C: Reversing valve.

49. A heat pump system uses a___________as a metering device.

D. Fixed orifice

50. The slide valve and piston in the reversing valve is actuated by pressure directed through the;

A: solenoid and pilot valve.

51. During the heating cycle, the outdoor coil becomes;

B: The evaporator.

52. During the cooling eyele, the indoor coil becomes;

B: an evaporator

53. During the defrost eycle, the outdoor fan is usually;

C: turned off

54. Larger heat pumps that use a thermostatic expansion valve at each coil will also have;

A: by-pass lines with check valves.

55. Refrigerant flow through the compressor;

C: is always the same regardless of operating mode.

56. Because of the possibility of liquid flood-back, a heat pump that uses a reciprocating compressor should be equipped with;

D: a suction accumulator

57. A scroll type compressor;

B: is less susceptible to damage from liquid flood-back.

58. On a "no heat / no cooling" service call, you turn the thermostat to the fan on /cont position and the indoor fan operates. This action verifies;

D:The transformer is functioning

59. On most air-to-air heat pumps;

B. the indoor and outdoor coid are of idfferent physical size and capacity

60. A heat pump system, operating at 45°F ambient, may be ____________efficient than electric resistance heat.

B: 3 to 4 times more.

61. Since electric resistance heat provides 1 watt of usable heat for each watt of energy purchased, electric resistance heat has a COP of;

A: 1 : 1

62. As outside ambient air temperature decreases, a heat pump's COP;

B: decreases.

63. During the defrost cycle, the system switches to the__________________ mode.

D. Cooling

64. During the heating mode, the refrigerant in the indoor coil is under;

B: high pressure

65. What three things happen on most air-to-air heat pumps during defrost?

C: The reversing valve must switch to cooling mode, the outdoor fan shuts off and auxiliary heat is energized.

66. High suction pressure and low discharge pressure on a heat pump system can be an indication of;

B. a step closed check valve

67. The PREFERRED method to perform adjustments to the refrigerant charge in a heat pump system is in the________mode.

B: cooling

68. You answer a service call for insufficient heat. You find the suction pressure is higher and discharge pressure is lower than normal. Using a digital thermometer, you measure the line entering the reversing valve from the compressor discharge and find 215F You then measure the line leaving the reversing valve that connects to the indoor coil and find 185F. These readings are an indication of;

B: a faulty reversing valve.

69. The customer complaint is not enough heat. You install service gauges and find low side pressure is higher than normal and the high side pressure is lower than the normal. You switch the system to the cooling mode and find the pressures a re normal. The most likely cause of the problem is;

A: a stuck open check valve at the outdoor coil.

70. A customer complains that their heat pump system blows cool air periodically during the heat mode. This could be caused by;

A: a faulty defrost relay (does not energize the aux, heat during the defrost mode).

71. When a heat pump is in the heat mode, frost ca n accumulate on the outdoor coil even when the ambient temperature is 45°F because;

A: the outdoor coil must be colder than the ambient air

72. The indoor fan on a heat pump system operates;

B. at the same speed for heating or cooling

73. The defrost cycle can be initiated by;

C. Time and temperature

74. The defrost eycle can be terminated by;

C. time/temp

75. Movement of the piston in the reversing valve is accomplished by;

C: bleeding pressure from one side of the piston to the suction side of the compressor

76. Some close coupled (package unit) heat pumps use an electronic expansion valve to meter refrigerant. One advantage to using an electronic expansion valve is;

B. electronic expansion valves can maeter refirgerant in either direction

77. Liquid line filter/driers that are used on heat pump systems;

C: must be a special bi-flow design if used without check valves.

78. When installing the heat pump outdoor unit, care should be taken to provide for drainage during the____cycle .

C: defrost

79. The indoor coil is usually mounted in the air stream__________the auxiliary electric heat strips.

A: before

80. When the auxiliary heat is gas or oil, the indoor coil must be located;

B: after the heat exchanger.

81. Air-to-air heat pumps are most practical to operate in areas where the lowest winter temperature does not go below____________*

A:+10

82. The air-to-air heat pump, operating without auxiliary heat, provides air to the registers that is approximately___________°F or less.

A: 100

83. The most common method of defrosting the outdoor coil on an air source heat pump is;

D: reverse cycle defrost

84. COP is the abbreviation for;

A: Coefficient of performance

85. At temperatures above 45 degrees *F, the heat pump refrigeration cycle permits the

A: Condenser to release 3 to 4 times more heat than it takes in electrical energy to drive the compressor.

86. In addition to heat from the outdoor coil, a heat pump in the heating mode will get heat from;

D. compression

87. When operating in the heat mode, hot gas leaves the compressor and first flows to;

D: the reversing valve.

88. When operating in the cooling mode, hot gas leaves the compressor and first flows to;

D: the reversing valve.

89. To make the reversing valve slide move, the system must have a pressure difference of;

C: 75 to 100 psig.

90. Before connecting your manifold gauge set to a heat pump system, you should first;

D. Verify the operating mode of the system

91. In the heat mode, the suction line entering the compressor contains;

C: low pressure/ low temperature vapor.

92. The reversing valve is often referred to as a;

C: three-way valve

93. A heat pump has a thermostatic expansion valve (TEV) and a check valve at each coil. When the modes are reversed;

C: refrigerant will bypass the TEV on the coil serving as the condenser.

94. Mechanically troubleshooting a reversing valve can be done by;

B. By checking the temperature differential between the connection serving the low side.

95. A reciprocating heat pump compressor differs from a light duty A/C compressor in that;

D. It is designed to operate at high compression ratios

96. One of the most important devices to insure the longevity of a heat pump's reciprocating compressor is the;

C: crankcase heater

97. A heat pump can be difficult to charge properly because;

D.

98. High efficient heat pump systems charged with R-410A refrigerant normally use a

C. fixed orifice metering device for the heating cycle and a TXV for the cooling cycle

99. When a heat pump is operating in the cooling mode, the;

C: indoor metering device is metering refrigerant and the outdoor check valve is open.

100. When in the cooling mode, the low pressure refrigerant vapor leaves the reversing valve and travels to the;

B: accumulator and then to the compressor