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HP > Heat Pump 2 > Flashcards

Heat Pump 2 Flashcards

1
Q

During the heating cycle, the outdoor coil is use as;

A

The evaporator.

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2
Q

During the cooling cycle, the indoor coil becomes;

A

The evaporator.

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3
Q

During the defrost cycle, the outdoor fan is usually;

A

Turned off.

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4
Q

Heat pump systems which use a thermostatic expansion valve at each coil will also have;

A

A by-pass lines with check valves.

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5
Q

Refrigerant flow through the compressor;

A

is always the same regardless of operating mode.

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6
Q

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

A

Suction Accumulator.

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7
Q

A scroll type compressor;

A

is less susceptible to damage from liquid flood-back.

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8
Q

On a split system heat pump. 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 that;

A

The transformer is functioning.

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9
Q

On most air-to-air heat pumps;

A

The indoor and outdoor coils are the same size and physical capacity.

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10
Q

A heat pump system, operating at 45°F ambient, may be _______ efficient than electric resistance heat

A

3 to 4 times more.

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11
Q

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

A

1:1

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12
Q

As outdoor ambient air temperature decreases, a heat pump’s COP;

A

Decreases.

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13
Q

During the defrost cycle, the system switches to the ___________ Mode.

A

Cooling.

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14
Q

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

A

High pressure.

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15
Q

What three things happen in most air-to-air heat pump during defrost?

A

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

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16
Q

High suction pressure and low discharge pressure on a heat pump system operating in either the heating or cooling mode can be an indication of;

A

Compressor inefficiency.

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17
Q

The preferred method to preform adjustments to the refrigerant charge in a heat pump system is in the ________ more.

A

Cooling.

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18
Q

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 215°F. You then measure the line leaving the reversing valve that connects to the indoor coil and find 185°F. These readings are an indication of;

A

A faulty reversing valve.

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19
Q

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

A

A stuck open check valve at the outdoor coil.

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20
Q

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

A

A faulty defrost relay (does not energized the aux. heat during the defrost mode.)

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21
Q

When a heat pump is in the heating mode, which can cause frost accumulation on the outdoor coil when the ambient temperature is 45*F?

A

The outdoor coil is colder than the ambient air.

22
Q

The indoor fan on a heat pump system operates;

A

At the same speed for heating or cooling;

23
Q

The defrost cycle can be initiated by;

A

Time and temperature.

24
Q

The defrost cycle can be terminated by;

A

Time/temperature

25
Q

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

A

Bleeding pressure from one side of the piston to the suction side of the compressor.

26
Q

Some close coupled (package unit) heat pumps use an electronic expansion valve is;

A

Electronic expansion valves can meter refrigerant in either direction.

27
Q

Liquid line filter-driers that are used on heat pump system;

A

Must be a bi-flow design if used without check valves.

28
Q

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

A

Defrost.

29
Q

The indoor coil is usually mounted in the air stream _______ the auxiliary electric heat strips.

A

Before.

30
Q

On Dual Fuel Systems, the indoor coil must be located;

A

After the heat exchanger.

31
Q

Air-to-air heat pumps are most practical to operate in areas where the lowest winter temperature does not go below ______ *F

A

+10

32
Q

Air-to-air heat pumps, operating without auxiliary heat, provide air to the registers that is approximately _______ *F or less.

A

100

33
Q

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

A

Reverse cycle defrost.

34
Q

COP is the abbreviation for;

A

Coefficient of performance.

35
Q

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.

36
Q

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

A

Compression.

37
Q

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

A

The reversing valve.

38
Q

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

A

The reversing valve.

39
Q

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

A

75 to 100 PSIG

40
Q

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

A
41
Q

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

A

Low pressure/low temperature vapor.

42
Q

The reversing valve is often referred to as a;

A

Four-way valve.

43
Q

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

A

Refrigerant will bypass the TEV on the coil serving as the condenser.

44
Q

Mechanically troubleshooting a reversing valve can be done by;

A

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

45
Q

Compressors designed for heat pumps differ from compressors designed for A/C in that;

A

It is designed to operate at high compression ratios.

46
Q

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

A

Crankcase heater.

47
Q

A heat pump can be difficult to charge properly because;

A

Heat pumps can only be charged in the cooling mode.

48
Q

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

A

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

49
Q

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

A

Indoor metering device is metering refrigerant and the outdoor check valve is open.

50
Q

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

A

Accumulator and then to the compressor.

HP (2 decks)

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