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HP > Heat Pump > Flashcards

Heat Pump Flashcards

1
Q

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 an

A

Reversing valve

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2
Q

What is the difference between “demand defrost” and “timed defrost”?

A

Demand defrost happens only when needed and timed defrost is based on time/temperature.

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3
Q

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

A

Outdoor ambient thermostat

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4
Q

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

A

Initial balance point

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5
Q

At what temperature is an outdoor ambient thermostat normally set?

A

Slightly above the initial balance point.

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6
Q

The outdoor coil is frozen solid on a “no heat” service call. The most likely reason is;

A

The outdoor fan is inoperative.

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7
Q

In order to determine a heat pumps’ balance point, you must first calculate;

A

The building’s heat load.

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8
Q

When a heat pump is used for heating and cooling, the system is sized by the;

A

Cooling load.

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9
Q

A high efficiency heat pump system designed to function from high to low ambient conditions below 10*F, may have?

A

Two outdoor coils with each one incorporating a dual stage compressor.

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10
Q

Room thermostats for heat pumps should be installed;

A

As near to the main return air grill as possible.

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11
Q

When the heat pump compressor has malfunctioned, the customer has the option to switch the system into;

A

Emergency heat mode.

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12
Q

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

A

Teach the customer how to program the thermostat.

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13
Q

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

A

Simulate the defrost cycle.

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14
Q

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

A

In a moderate climate zone.

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15
Q

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

A

ECM fan motors.

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16
Q

How may a lockout (impedance) relay be reset?

A

Simply disconnect power to the unit momentarily.

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17
Q

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

A

Approximately 2*F

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18
Q

SEER is calculated by;

A

Dividing the Btu’s removed by the watts consumed during the cooling season.

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19
Q

If the indoor fan is operated at an excessive speed in the cooling mode;

A

The system will not properly remove the humidity from the conditioned space.

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20
Q

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

A

By weight

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21
Q

What is the industry standard for deep vacuum?

A

Maintain 500 microns for 15 minutes.

22
Q

Good service practice for installation of a reversing valve includes;

A

Use heat paste and wet rags while brazing in the new valve.

23
Q

Off-cycle crankcase heat is provide by;

A

A small amount of current is passed through the start capacitor to start the heat winding.

24
Q

You are checking for proper airflow in CFM on a three ton heat pump system. The system has one return grill measuring 24”X24”, which has a net free area of 3.4 square feet. You measure air velocity and calculate an average of 400 FPM. From this information you can conclude that;

A

Airflow in CFM is below normal range.

25
Q

What control operates the 1st stage of secondary heat?

A

The second heating stage of the indoor thermostat.

26
Q

What is the industry standard for maximum duration for defrost?

A

A maximum of 10 minutes.

27
Q

What is the recommended CFM across the evaporator cool of a heat pump?

A

400 to 450 CFM

28
Q

If manufacturer specifications are not available, a good way to calculate cubic feet per minute through a coil is to;

A

Use temperature rise on emergency heat mode.

29
Q

What type of defrost is employed on this heat pump?

A

Time or temperature initiation, time and temperature termination.

30
Q

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

A

The defrost relay.

31
Q

When this unit switches to the heat mode, select the sequence of events which will take place.

A

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

32
Q

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

A

The DFR N.O. contacts close, which forms a holding circuit.

33
Q

How is defrost terminated in this system?

A

Either the time or temperature termination requirements has been satisfied.

34
Q

Where is the LLP physically located in this system on this heat pump?

A

On the bi-flow liquid line located between the two coils.

35
Q

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

A

Increase the indoor fan speed.

36
Q

Heat pump mode efficiency is rated in;

A

HSPF.

37
Q

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

A

Direct acting.

38
Q

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;

A

4.6:1

39
Q

Which type of heat pump does not require a defrost cycle?

A

Water source.

40
Q

An R-410A heat pump operating in the cooling mode has a suction pressure of 131 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?

A

12 Degrees

41
Q

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

A

Every 30 or 90 minutes, depending on the cam installed in the timer.

42
Q

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

A

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

43
Q

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
Q

When a heat pump is operating in the heat mode, the suction line at the compressor;

A

Cold and sweaty

45
Q

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

A

Suction line accumulator.

46
Q

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

A

A stuck check valve or clogged TXV screen.

47
Q

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;

A

The charge is critical, sometimes to 1/2 oz. refrigerant

48
Q

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

A

Reversing valve.

49
Q

Some heat pump systems use a ______________ as a metering device.

A

Fixed orifice.

50
Q

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

A

Solenoid and pilot valve.

HP (2 decks)

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