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HVAC Flashcards

Study For First Test

1
Q

What is the second law of thermodynamics according to Randy?

A

Heat flows from hot to cold.

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2
Q

What does BTU mean?

A

British Thermal Unit

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3
Q

What are the two ways to cool a structure

A

Sensible Heat and Latent Heat

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4
Q

Does Latent Mean Hidden in Latin?

A

Yes

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5
Q

What does it mean when we speak of Latent?

A

That we are going to remove water or moisture from the air

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6
Q

What are the forms of water?

A

Solid, Water and Gas

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7
Q

There exist to types of latent heat of fusion for water which are they?

A

Latent Heat of Freezing and Latent Heat of Melting

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8
Q

400 Series Refrigerants like 410A or 407 are what type of refrigerants

A

Zeotropes meaning a combination of two substances

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9
Q

How do we charge refrigerants according to Randy?

A

As a liquid not a gas

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10
Q

What is Super Heat?

A

The temperature ABOVE saturation

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11
Q

What is Super Cool?

A

The temperature BELOW saturation

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12
Q

The Greater The Temperature The Greater the?

A

Heat flow

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13
Q

What does hermetic mean?

A

All inclusive or enclosed

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14
Q

How does a compressor cool itself down?

A

Cool Suction Line Vapors

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15
Q

How many BTUs does it take to place 1 pound of water into the air?

A

970 BTUs

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16
Q

What is Dew Point?

A

This is when the air cannot hold any more moisture

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17
Q

Gases occupy?

A

All Space They Are in

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18
Q

What is the Latent Heat of Ice?

A

144 BTUs

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19
Q

Who does more work sensible heat or latent heat?

A

Latent Heat

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20
Q

PSI means pounds per square inch. What does PSIG mean?

A

The G stands for gauge. This means the PSI inside the system the gauges are measuring

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21
Q

What are the two ways a compressor can fail?

A

Mechanically or Electrical

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22
Q

How do you measure super heat?

A

On the low side of the system you convert the pressure to temperature then subtract that from the actual temperature in the suction line and you have the super heat

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23
Q

The actual second law of thermodynamics is

A

energy cannot be created nor destroyed

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24
Q

What does Delta T (ΔT) mean?

A

Change in temperature. Delta or the triangle symbol means change in HVAC Delta T means the change between ONE substance.

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25
Q

TD (TΔ) Means?

A

This is the change between TWO substances

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26
Q

Which do we want to measure in air conditioning Delta T (ΔT) or T Delta (TΔ)

A

Delta T (ΔT)

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27
Q

1 Pound of Water in the AIR equals?

A

1 Pint of Actual Water

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28
Q

How many cubic feet per minute (CFM) are in one ton?

A

400 CFM

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29
Q

1 Watt Generates how many BTUs an hour?

A

3.414 BTUs

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30
Q

What does charging a system mean?

A

It means either adding or removing refrigerant

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31
Q

What do you calibrate your gauges too?

A

0 or 14.7 atmospheric pressure

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32
Q

400 Series refrigerants are charged how?

A

As liquid because they are zoetrope

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33
Q

What type of heat does not create a change in temperature?

A

Latent Heat

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34
Q

Is Nitrogen a Non-Condensable gas?

A

Yes

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35
Q

Is Moisture a Non-Condensable Gas?

A

No

36
Q

When do you mix refrigerants?

A

Never under NO exception do you mix them

37
Q

When do you purge your manifolds?

A

Always Before and After Using them

38
Q

What volt ranges will you experience?

A

208v, 460v, 1v, 25v and 24v

39
Q

In a thermostat what does the R wire mean?

A

Power

40
Q

In a thermostat what does the G wire mean?

A

Fan

41
Q

In a thermostat what does the W wire mean?

A

Heat

42
Q

In a thermostat what does the Y wire mean?

A

Cool

43
Q

In a thermostat what does the C wire mean?

A

Common

44
Q

What tool is used to measure Voltage?

A

Voltmeter

45
Q

What tool is used to measure Amps?

A

Ampmeter

46
Q

What tool is used to measure OMHs?

A

OMH Meter

47
Q

What does induced mean?

A

Magnetic Field

48
Q

Amps are measured how with a amp meter?

A

In Series?

49
Q

How do you test OHMs?

A

You first need to turn off the power

50
Q

What does OL mean in a meter?

A

Open Line

51
Q

NO and NC mean what?

A

Normally Open & Normally Closed

52
Q

What is a motor?

A

Electrical energy turned into mechanical motion

53
Q

What does RLA on a compressor mean?

A

Rated Loaded Amps

54
Q

What 3 pins do one phase motors have?

A

Run, Start, Common

55
Q

How many winding’s do 3 phase motors have?

A

3

56
Q

What is the resistance between all 3 windings in 3 phase motors?

A

It is all the same resistance or OHMs

57
Q

PSC Motors means?

A

Permanent Split Capacitor motor

58
Q

What are the 3 ways heat can be transfered?

A

Radiation, Conduction and Convection

59
Q

12,000 BTU equals how much

A

1 Ton

60
Q

How do we measure a vacuum?

A

Inches of mercury

61
Q

What is voltage or EMF?

A

The flow of electrons caused by a potential difference in atomic charge

62
Q

What is resistance? or OMH

A

How resistant a material is to the flow of electrons on its surface.

63
Q

What is an electrical circuit?

A

A COMPLETE path for electrons to flow

64
Q

What is a LOAD?

A

Any device that consumes electricity to perform work

65
Q

What is induced magnetism?

A

When any material being capable of being magnetized becomes a magnet and is placed inside a magnetic field.

66
Q

What happens when you move a conductor across a magnetic field?

A

If a conductor is moved across a magnetic field an electromotive force EMF will be generated that induces current in the conductor

67
Q

What is a relay?

A

a relay is an electrical switching device that turns lets power flow or stops the flow of power

68
Q

What is a Solenoid?

A

is an electromagnetic device that has a plunger that is pulled down when current flows and when current stops it pulls the plunger back

69
Q

What are the two main parts of a motor?

A

A Stator and Rotor

70
Q

What happens to a motor when it is placed under a heavy load? or work?

A

It increases its consumption of electricity increases greatly

71
Q

How does a motor start?

A

Through phase splitting between the Run and Start windings

72
Q

You can add WHAT and HOW to a motor run and start windings?

A

A capacitor in series to the START winding

73
Q

What two types of capacitors are used in a motor?

A

Run and Start Capacitors

74
Q

Can you place a capacitor in the motors stator windings?

A

NO

75
Q

What is a CSIR motor?

A

A single phased motor with a start capacitor wired IN SERIES with the motor

76
Q

What is a Hermetic Compressor Motor?

A

is a motor enclosed inside with the compressor

77
Q

VOLTMETERS are used to measure what?

A

Volts

78
Q

How are VOLTMETERS connected when testing a circuit?

A

In Parallel

79
Q

How are OHM meters connected when testing a circuit?

A

In Series

80
Q

What do clamp ampmeters do?

A

Measure the alternating current flowing through the conductor

81
Q

What is a metering orifice

A

A fixed orifice (hole) used as a metering device for refrigerant before it enters the evaporator

82
Q

What happens when you increase super heat too much?

A

This starves the evaporator by only allowing an amount of liquid refrigerant into the evaporator

83
Q

What does CS mean in CSIR and CSCR

A

Capacitor Start

84
Q

How are capacitors wired in a CSCR Motor

A

The start and run capacitor are wired in SERIES with the START winding BUT the run capacitor and start capacitor are wired in parallel

85
Q

How do CSCR Motors work?

A

Current runs through both run and start windings creating phase splitting which produces high torque but the start capacitor drops out after the motor has reached its desired levels

86
Q

How does a PSC Motor (permanent split capacitor) work?

A

Current flows through the run,start and the capacitor during the motors whole operation

Test (1 decks)

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