Efficient Gas-Fired, Forced-Air Heating Systems

Question 1

The combustion air prove switch is normally closed.

True or False

Answer 1

False

Question 2

The roll-out switches are normally closed, automatic reset safety device.

True or False

Answer 2

False

Question 3

List the three types of electronic ignition systems used in furnaces

Answer 3

a) Combination spark electrode and flame sensor
b) Intermittent pilot ignition system
c) Hot surface ignition system

Question 4

The primary high limit switch is a normally closed device that opens if excessive temperature is sensed:

a) over the burner
b) in the flue
c) in the blower compartment
d) in the heat exchanger compartment

Answer 4

d) in the heat exchanger compartment

Question 5

The intermittent pilot ignition system requires a voltage input of:

a) 24 V ac
b) 24 V dc
c) 120 V ac
d) a very high stepped-up voltage

Answer 5

c) 120 V ac

Question 6

Electronic control board features are standard for all models of furnaces.

True or False

Answer 6

Fasle

Question 7

List the four types of humidifiers that can be used on furnaces

Answer 7

a) Standing water-absorbent pad
b) Rotating drum
c) Rotating disk
d) Flow through (flow-thru) humidifier

Question 8

Electrostatic filters are designed to remove microscopic particles from circulating air by using charged plates that attract contaminants as they pass through the filter.

True or False

Answer 8

True

Question 9

Explain why a common air exhaust system must be interlocked with the furnace fan blower.

Answer 9

If air is exhausted out of a building, a negative pressure occurs within the building. If the air is not replaced, the negative pressure pulls outside air back into the building through the chimney flue. If the furnace is running when this happens, there is a possibility of carbon
monoxide poisoning.

Question 10

What is the minimum number of air changes per hour (ACH) the average home should have?

a) 0.15 ACH
b) 0.25 ACH
c) 0.35 ACH
d) 1.00 ACH

Answer 10

c) 0.35 ACH

Question 11

The collector plates of an electronic air filter have a positive charge.

True or False

Answer 11

False;

The collector plates are (-) and dust particles (+)

Question 12

Not all high efficiency furnaces require a condensate drain line.

True or False

Answer 12

False

Question 13

The secondary heat exchanger of a high efficient furnace can produce liquid carbonic acid.

True or False

Answer 13

True

Question 14

A power drum humidifier should operate whenever the associated humidistat is closed, regardless of furnace operations.

True or False

Answer 14

False

Question 15

Which statement best describes a modern direct drive blower motor?

a) A fan belt connects the fan to the blow motor
b) The fan is mounted directly on the motor shaft
c) Fan brushings and bearings that need regular maintenance
d) Both a and c

Answer 15

b) The fan is mounted directly on the motor shaft

Question 16

A sealed combustion chamber prevents already heated air from being used for combustion air

True or False

Answer 16

True

Question 17

A hot surface igniter typically heats up to temperatures over 2000 Degrees Celsius

True or False

Answer 17

False

Question 18

Another name for a high-efficiency furnace is:

a) conventional furnace
b) combustion furnace
c) condensing furnace
d) secondary furnace

Answer 18

c) condensing furnace

Question 19

A typical installation of the humidistat can be:

a) near the thermostat
b) on the return air duct
c) in the heat exchanger
d) all of the above
e) either a or b

Answer 19

e) either a or b

Question 20

A flame rod, used as a flame proving device, makes use of:

a) a capillary tube to carry the current
b) flame to provide a current path
c) the bimetal flame proving principle
d) the magnetic properties of flame

Answer 20

b) flame to provide a current path

Question 21

The heat recovery ventilator is electrically interlocked with the:

a) main blower
b) exhaust fans
c) combustion air blower
d) both a and b

Answer 21

d) both a and b

Question 22

It is common for a mid-efficient furnace to have multiple high limit safety switches.

True or False

Answer 22

True

Question 23

A dual stage burner valve will run the burner flame on a high setting if more heat is required.

True or False

Answer 23

True

Question 24

Which of the following was a method of increasing the efficiency of the heat exchanger from a standard furnace to an efficient furnace?

a) tubular design
b) increased surface area
c) using metals with better heat transfer properties
d) all of the above

Answer 24

d) all of the above

Question 25

The device that keeps the products of combustion seprate from the indoor air is the:

a) combustion air blower
b) heat exchanger
c) plenum
d) all of the above

Answer 25

b) heat exchanger

Question 26

The purge time adjustment for the combustion air blower is typically made by a DIP switch on the electronic control board.

True or False

Answer 26

False

Question 27

Ignition in a mid-efficient furnace is achieved using:

a) a flame rod
b) a hot surface
c) a spark electrode
d) both b and c
e) all of the above

Answer 27

d) both b and c

Question 28

A common type of humidifier for a furnace is the:

a) standing water absorbent pad
b) rotating disk
c) flow through
d) any of the above

Answer 28

d) any of the above

Question 29

Some manufactures call the secondary heat exchanger in a condensing furnace a:

a) condenser coil
b) evaporator coil
c) remote radiator
d) hot plate

Answer 29

a) condenser coil

Question 30

The combustion air blower forces air directly into the:

a) heat exchanger
b) plenum
c) flue
d) cold air return duct

Answer 30

c) flue