Midterm

Question 1

The condition that occurs when a person cannot sense the difference between themselves and the surrounding air.

Answer 1

Comfort

Question 2

The condition that occurs when a person can sense the difference between themselves and the surrounding air.

Answer 2

Discomfort

Question 3

A method of heat transfer
caused by the direct physical contact of substances.

Answer 3

Conduction

Question 4

A method of heat transfer
in which heat is moved from one location to another through the circulation of a substance.

Answer 4

Convection

Question 5

A method of heat transfer in which invisible heat rays move heat.

Answer 5

Radiation

Question 6

What are the two main causes of combustion inefficiency?

Answer 6

incomplete combustion and an excess amount of air

Question 7

How many conditions must be known in order to complete a psychrometric chart?

Answer 7

2 of the 7

Question 8

How is a vacuum measured?

Answer 8

In inches of mercury

Question 9

Define Absolute pressure.

Answer 9

Any pressure above a perfect vacuum (0 psi).

Question 10

Define a Vacuum.

Answer 10

Any pressure that is less than atmospheric pressure.

Question 11

The force exerted by the weight of the atmosphere (gas molecules) on the earth’s surface.

Answer 11

Atmospheric pressure.

Question 12

A pressure measurement above atmospheric pressure that is used to express pressure derived from the operation of a closed system.

Answer 12

Gauge pressure

Question 13

The ability of a material
to hold heat.

Answer 13

Specific heat

Question 14

The measurement of a liquid’s resistance to flow (thickness).

Answer 14

Viscosity

Question 15

The process of breaking a liquid into small droplets.

Answer 15

Atomization

Question 16

A chemical reaction in fuel that occurs when oxygen reacts with hydrogen (H) and carbon (C) at an ignition temperature.

Answer 16

Combustion

Question 17

How are air conditioning systems cooling often measure in?

Answer 17

Tons

Question 18

Define a British thermal unit (Btu)

Answer 18

The quantity of heat required to change the temperature of 1 lb of water 1°F.

Question 19

Define a ton.

Answer 19

The amount of heat required to melt one ton of ice (2000 lbs) over 24 hr. One ton of cooling equals 12,000 Btu/hr or 288,000 Btu/24 hr (12,000 x 24 = 288,000).

Question 20

Define Humidity

Answer 20

The amount of moisture, or water vapor, in air.

Question 21

What determines the amount of ventilation necessary for comfort?

Answer 21

The number of occupants and the kind of activity taking place inside the building.

Question 22

The amount of work that can be performed by a force.

Answer 22

Energy

Question 23

What are the different forms of energy? (7)

Answer 23

Heat (thermal), gravity, sounds, light, chemical, electrical, and mechanical energy.

Question 24

What is occurring when an insufficient amount of oxygen is supplied by combustion air to combine with all the elements in a fuel?

Answer 24

Incomplete combustion

Question 25

The temperature of air if it was cooled to 100% relative humidity?

Answer 25

Wet-bulb temperature

Question 26

What is the energy of work?

Answer 26

Mechanical

Question 27

The heat applied to or removed from a substance that results in a temperature change?

Answer 27

Sensible heat

Question 28

The heat applied to or removed from a substance that results in a change of state.

Answer 28

Latent heat

Question 29

What are the oxygen, carbon dioxide, and carbon monoxide levels of a fuel used to determine?

Answer 29

Combustion efficiency

Question 30

Any substance that is burned to produce heat.

Answer 30

A fuel

Question 31

Fuel, oxygen, and ignition temperature are the three requirements of what process?

Answer 31

Combustion

Question 32

What two readings are used to adjust a burner so that it will operate as efficiently as possible?

Answer 32

Carbon dioxide and flue-gas temperature

Question 33

People tend to have the best comfort at a what relative humidity?

Answer 33

45%

Question 34

A graph that defines the properties of air at various conditions.

Answer 34

Psychrometric chart

Question 35

What temperature is the temperature at which water vapor in the air begins to condense?

Answer 35

Dewpoint

Question 36

The process of reducing air pollution by introducing enough fresh outdoor air into a building to dilute indoor pollutants.

Answer 36

Ventilation

Question 37

Building HVAC systems typically use what for heating and cooling?

Answer 37

Furnace or boilers for heating and air conditioners or chillers for cooling.

Question 38

What air velocity, in buildings, is considered ideal for comfort?

Answer 38

40 fpms

Question 39

A self-contained building cooling unit that has the components contained in one cabinet.

Answer 39

A packaged unit

Question 40

The amount of moisture in the air compared to the amount of moisture the air would hold at the same temperature when air is saturated, or full of moisture.

Answer 40

Relative humidity

Question 41

What device removes moisture from the air by causing the moisture to condense or be trapped?

Answer 41

A dehumidifier

Question 42

The rate at which work (in ft-lb) is produced per unit of time (in sec).

Answer 42

Power

Question 43

A colorless and odorless gas fuel.

Answer 43

Natural gas

Question 44

What takes place in a furnace or boiler to heat a building?

Answer 44

Combustion

Question 45

What type of combustion occurs when enough oxygen is supplied by combustion air to combine with all elements in a fuel?

Answer 45

Complete combustion

Question 46

What type of air is provided to a burner for the proper combustion of a fuel?

Answer 46

Combustion air

Question 47

The point at which a flame is established.

Answer 47

Burner face

Question 48

The temperature of air as taken with a standard thermometer.

Answer 48

Dry-bulb temperature

Question 49

The total amount of heat contained in a substance.

Answer 49

Enthalpy

Question 50

What is used to express enthalpy?

Answer 50

BTUs

Question 51

The carbon dioxide and other va- pors that exit a furnace or boiler to the atmosphere using a flue, which is a pipe or channel for conveying exhaust gases.

Answer 51

Flue gas