Principles Of Automatic Heating And Cooling Controls

Question 1

What is meant by the term cold?

Answer 1

Cold is the relative lack of heat

Question 2

What is the approximate definition of BTU?

Answer 2

British Thermal Unit

- The amount of heat required to raise the temperature of 1 pound of water by 1 degree F.

Question 3

Heat transfer in an object is always from hot to cold.

True or False?

Answer 3

True

Question 4

Convection is the way heat is transferred by…

Answer 4

Fluids

Question 5

Referring to heating/cooling systems, list 4 factors that affect human comfort.

Answer 5

Temperature
Humidity
Air movement
Radiation

Question 6

In a closed loop system, feedback is optional.

True or False?

Answer 6

False.

Question 7

A device that reacts to changes in a variable condition is referred to as:

1. a relay device
2. a controlling device
3. an igniting device
4. a load device

Answer 7

Controlling device

Question 8

A limit or safety device detects dangerous conditions in the system.

True or False?

Answer 8

True

Question 9

A control circuit for a residential heating system is an example of a closed loop control system.

True or False?

Answer 9

True

Question 10

The heat exchanger:

1. contains the heated air that is distributed by the ducts
2. is a mechanical device that opens to allow heated air into a room
3. is an electrical device that opens a damper to allow heated air into a room
4. is a steel enclosure that transfers heat to the air distributed by the ducts

Answer 10

4. is a steel enclosure that transfers heat to the air distributed by the ducts

Question 11

In a domestic gas furnace the fan motor starts when:

1. the room thermostat contacts close to call for heat
2. the main burner gas valve opens
3. the air in the plenum warms up to a preset temperature
4. the thermocouple produces sufficient voltage to pull in the relay

Answer 11

3. the air in the plenum warms up to a preset temperature

Question 12

If the plenum gets to hot the high limit device will shut off the fan motor.

True of False?

Answer 12

False

Question 13

In a properly operating domestic gas furnace the fan motor could keep running after the main burner shuts off.

True of False?

Answer 13

True

Question 14

A schematic diagram is used to show

1. the location of components
2. the relative size of components
3. the logical operation of components
4. the electrical rating of components

Answer 14

3. the logical operation of components

Question 15

If you wanted to find out the relative position of components in a heating system and the wiring between them, you would look at

Answer 15

A wiring diagram

Question 16

A schematic diagram is drawn with

1. Power on and at 20 degrees C
2. Power off and no heat
3. Power on and no heat
4. Power of and at 20 degrees C

Answer 16

2. Power off and no heat

Question 17

An example of a load device is

1. A thermostat
2. An N.O. contact
3. A high limit switch
4. A relay coil

Answer 17

4. A relay coil

Question 18

An example of a controlling device is

1. a heater
2. a pressure switch
3. a motor
4. Both 1 and 3

Answer 18

2. a pressure switch

Question 19

A gas fired furnace in a single dwelling always needs a properly labeled disconnect switch near the furnace

True or False?

Answer 19

False

Rule 26-806

Question 20

A residential furnace is allowed to have the light in the furnace room on its supply circuit.

True or False?

Answer 20

False

Rule 26-806

Question 21

The 24V Class 2 control wiring to the thermostat for residential gas fire heating systems can utilize LVT cable.

True or False?

Answer 21

True

Rule 16-210
Table 19

Question 22

In a forced air furnace the sensing element for the fan is mounted in the heat exchanger.

True or False?

Answer 22

False

Question 23

People may feel cold even if the temperature is 20 degrees C

a) False
b) True, if the humidity is to high
c) true if the humidity is to low
d) true if there is insufficient air movement over the body

Answer 23

c) true if the humidity is to low

Question 24

When control devices in a domestic heating system are connected such that any “1” device could deactivate the main gas valve the devices would be connected in

Series or Parallel?

Answer 24

Series

Question 25

A forced air system relies on gravity to circulate the warm air. True or False?

Answer 25

False

Question 26

Two control devices are connected in series to control one load device. One control device is closed and the other is open. The load device will be: a) On b) Off c) On or Off depending on something d) Not working properly

Answer 26

b) Off

Question 27

A human body can lose heat by radiation if it is to close to a cold wall. True or False?

Answer 27

True

Question 28

Low relative humidity can make a room feel colder than it actually is. True or False?

Answer 28

True

Question 29

In a forced air gas furnace, the smoke and exhaust gasses are found: a) inside the heat exchanger b) in the plenum c) at the registers d) in the duct

Answer 29

a) inside the heat exchanger

Question 30

If the temperature becomes dangerously high in a domestic forced air furnace, which device should safely shut down the heating equipment. a) the high limit b) the fan limit c) auxiliary contact d) thermocouple

Answer 30

a) the high limit

Question 31

Rules pertaining to the installation of HVAC systems and equipment are grouped into one section of the code book? True or False?

Answer 31

False

Question 32

Convection is a method by which heat is transferred through solids. True or False?

Answer 32

False

Question 33

Thermostatically controlled heating systems are considered _______ loop systems

Answer 33

Closed

Question 34

A heating thermostat symbol on a schematic should be shown a) N.C. and opens on a rise of temperature b) N.O. and closed on a drop in temperature c) N.O. and closes on a rise in temperature d) None of the above

Answer 34

a) N.C. and opens on a rise of temperature

Question 35

Controlling devices react to changes in variable conditions such as temperature, pressure or humidity. True or False?

Answer 35

True

Question 36

What is meant by the term heat?

Answer 36

Heat is energy in transfer