Hvac Fundamentals

Question 1

What is a reamer blade used for?
A. Cutting tubing
B. Cutting sheet metal
C. Removing burrs from inside of tubing
D. Removing sweat type filter driers

Answer 1

C. Removing burrs from inside of tubing D

Question 2

If the pressure exerted upon a liquid is reduced, what effect does this have on the liquids boiling point temperature?

A. It raises the boiling point
B. It lowers the boiling point
C. It has no effect on the boiling point
D.it either raises or lowers the boiling point, dependent on the liquid

Answer 2

B. It lowers the boiling point C

Question 3

An exposed central support that runs parallel to the ceiling is called a
A. Beam
B. Joist
C. Stud
D. Plate

Answer 3

A. Beam

Question 4

What should always be worn when brazing?
A. A respirator
B. Earplugs
C. Tinted safety glasses or goggles
D. A personal alarm

Answer 4

C. Tinted safety glasses or goggles D

Question 5

Why would earmuffs or plugs be important in this field ?

Answer 5

For when you are fabricating sheet metal or working with small machines

Question 6

When using any electrical tool with a cord, you should always connect that tool to what?

Answer 6

GfCI or wall plug.

Question 7

There are two type of hazards that you can encounter when brazing and soldering, what are those two things?

Answer 7

1. The heat coming off the materials you are using
2. The other involves the fumes from the gases used in each process

Question 8

When brazing what two safety equipment items should you be using and what for?

Answer 8

1. Gloves to protect your hands from the heat
   2.Safety goggles to protect your eyes from the brightness of the torch

Question 9

What are the three things you should never let oxygen come in contact with?

Answer 9

1.oil
2.grease
3. Flammable substances

Question 10

At what psi does Acetylene become unstable?

Answer 10

Anything over 15psi

Question 11

True or False you can get Acetylene tanks filled up anywhere

Answer 11

False. Only authorized gas distributors should refill them

Question 12

What are the two acceptable purging gases used in the field?

Answer 12

1.Nitrogen
2.carbon Dioxide

Question 13

What psi should you set your regulator on your nitrogen bottle when brazing?

Answer 13

You should set your regulator to 1 or 2 psi

Question 14

Why should you let nitrogen flow through the lines when you braze?

Answer 14

To minimize the oxidation inside the piping

Question 15

Nitrogen is not hazardous
True or False

Answer 15

False. Nitrogen is an inert gas, it can displace oxygen and result in oxygen deprivation

Question 16

Is nitrogen heavier or lighter than air?

Answer 16

It is lighter

Question 17

What type of fire extinguisher do you need in your truck and why?

Answer 17

You need a class b fire extinguisher made for chemical fires

Question 18

Before you work with any gases involved in brazing and soldering what should you read first?

Answer 18

The SDS or SAFETY DATA SHEET

Question 19

What is the maximum temperature you can keep a refrigerants cylinder in an area?

Answer 19

125F

Question 20

Girders and trusses are used for what in construction?

Answer 20

Support

Question 21

What is a Girder?

Answer 21

It’s a main component in a framed floor and support the joist that hold the flooring boards

Question 22

What is a TRUSS?

Answer 22

It’s a combination of structures creating a framework to connect load bearing walls

Question 23

What would a beam be used for in construction?

Answer 23

It’s generally engineered to carry structural loads over long open spans

Question 24

What is a JOISTS in construction?

Answer 24

Are small rectangular sections of wood that rest on wall framing and support the ceilings and floors

Question 25

What three things must be present for combustion to happen?

Answer 25

1.Fuel 2.oxygen 3.heat

Question 26

What is Pascal’s law?

Answer 26

States that gas exerts equal pressure in all directions in a closed container

Question 27

What is Charles law?

Answer 27

States that the volume of a gas is directly proportional to the absolute temperature.

Question 28

What is the equation for Charles law?

Answer 28

Vi/vf = Ti/Tf

Question 29

What does Vi and Vf stand for?

Answer 29

Initial and final volume

Question 30

What does Ti and Tf stand for?

Answer 30

Initial and final temperature

Question 31

What is Boyle’s Law?

Answer 31

States that an increase in pressure on a gas causes a decrease in its volume

Question 32

What is the Gay-Lussac’s Law?

Answer 32

States the pressure of a gas is directly proportional to it’s temperature

Question 33

What is subcooling?

Answer 33

The temperature of the liquid refrigerant leaving the condenser of a ac unit

Question 34

What is superheat?

Answer 34

The temperature of vapor refrigerant leaving the evaporator of an ac unit

Question 35

What’s the difference between class 1 wiring and class 2 wiring?

Answer 35

Class 1 wiring is used for thermostats, with a maximum of 30 volts Class 2 circuit provides power to the equipment with acceptable protection from electrical shock

Question 36

What does AHRI stand for and what it means?

Answer 36

The air conditioning, heating and refrigeration institute And it develops standards and guidelines meant to improve product performance

Question 37

Propane and Butane are (BLANK) than air

Answer 37

Heavier

Question 38

Gas valves operating in furnaces, boilers, and larger appliances have a typical voltage rating of what?

Answer 38

24v

Question 39

Sight glass is present at the (BLANK) in the refrigeration cycle

Answer 39

Liquid line

Question 40

What is used to remove the trapped air from a low pressure system from the top of the condenser?

Answer 40

Purge unit

Question 41

What is used to remove the trapped air from a low pressure system from the top of the condenser?

Answer 41

Purge unit

Question 42

Which of the following law states that the total pressure of a confined mixture of gases is the sum of pressures of each of the gases in the mixture

Answer 42

Daltons Law

Question 43

The Curved boundary In Psychrometric chart indicates what?

Answer 43

Saturation

Question 44

1 horsepower = how many watts?

Answer 44

746

Question 45

reclaimed refrigerant must meet the standards of (BLANK) before it can be resold:

Answer 45

ARI 700

Question 46

In a Psychrometric chart, dew point temperature lines are represented as:

Answer 46

Lines parallel to x axis

Question 47

What is a Fuse used for?

Answer 47

It prevents short circuits

Question 48

Which compressor operates most efficiently with high molecular weight, and high specific volume refrigerant?

Answer 48

Centrifugal compressor

Question 49

Based on average conditions what percentage is the refrigerant holding capacity of an accumulator ?

Answer 49

65%

Question 50

The horsepower required for any fan or blower varies directly as the (Blank) of the speed?

Answer 50

CUBE

Question 51

What is diminished by the fan’s velocity pressure?

Answer 51

Static pressure

Question 52

The higher the suction pressure the greater efficiency of the what?

Answer 52

Compressor

Question 53

Which compressor has pulsations?

Answer 53

Reciprocal Compressors

Question 54

An amperage is a measurement of what?

Answer 54

Electric current

Question 55

Locked Rotor Ampere (LRA) current of a motor will be typically how many times more the normal running current of a motor

Answer 55

5 to 7 times

Question 56

As the moisture present in the air increases, the wet bulb depression does what?

Answer 56

Decreases The wet bulb depression is the difference between the dry bulb temperature and the wet bulb tem-perature.

Question 57

What is the cubic feet of the mixture per pound of dry air?

Answer 57

Specific volume

Question 58

Variable Speed Drive (VSD) systems used in HVAC applications works by converting the AC main supply to DC using what?

Answer 58

Rectifier

Question 59

The (BLANK) is made of two different metals that expand at different rates when heated and is used as a switch that turns on/off the air conditioning sys-tem.

Answer 59

Bimetallic strip

Question 60

A motor contactor main purpose is to what?

Answer 60

Turn the motor on and off

Question 61

Low pressure steam boilers will have operating pressure less than what psi?

Answer 61

15psi Low-pressure steam boilers are typically used in residential and commercial applications where the need for high-pressure steam is not required.

Question 62

According to ASME, the safety valve of the boiler should be tested every how many days ?

Answer 62

30 or a month

Question 63

For every 1000 feet above sea level, the capacity of a natural gas furnace is de-rated by what percentage?

Answer 63

4% This is because the air is less dense at higher altitudes, which means that there is less oxygen available for combustion. As a result, the furnace has to work harder to produce the same amount of heat, which can lead to decreased efficiency and increased wear and tear on the unit.

Question 64

Dew point temperature is the temperature at which web bulb temperature is (BLANK) to dry bulb temperature

Answer 64

Equal too

Question 65

Which of the following is not correct with respect to water tube boilers: Higher steam output Smaller size Operate at lower pressures Longer life span

Answer 65

Operate at lower pressures Longer

Question 66

What is used to measure the pressure drop across the air filters:

Answer 66

Manometer

Question 67

(BLANK) is the temperature which moisture condenses out the air

Answer 67

Dew point temperature

Question 68

An oil separator is located in the (BLANK) of the refrigeration cycle.

Answer 68

Discharge line

Question 69

What is an oil separator?

Answer 69

device that removes oil from the refrigerant as it flows from the compressor to the condenser.

Question 70

What compressor uses two special helical rotors that introduce suction vapors and compress them?

Answer 70

Scroll compressor

Question 71

What is used to control the flow of refrigerant in an air conditioning or refrigeration system?

Answer 71

Expansion valve

Question 72

The presence of refrigerant vapor upstream of the (BLANK) is very undesirable

Answer 72

Expansion valve

Question 73

Oxygen will explode when it comes into contact with compressor oil in refrigeration system True or false

Answer 73

TRUE