Efficient Gas-Fired, Forced-Air Heating Systems Flashcards
The combustion air prove switch is normally closed.
True or False
False
The roll-out switches are normally closed, automatic reset safety device.
True or False
False
List the three types of electronic ignition systems used in furnaces
a) Combination spark electrode and flame sensor
b) Intermittent pilot ignition system
c) Hot surface ignition system
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
d) in the heat exchanger compartment
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
c) 120 V ac
Electronic control board features are standard for all models of furnaces.
True or False
Fasle
List the four types of humidifiers that can be used on furnaces
a) Standing water-absorbent pad
b) Rotating drum
c) Rotating disk
d) Flow through (flow-thru) humidifier
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
True
Explain why a common air exhaust system must be interlocked with the furnace fan blower.
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.
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
c) 0.35 ACH
The collector plates of an electronic air filter have a positive charge.
True or False
False;
The collector plates are (-) and dust particles (+)
Not all high efficiency furnaces require a condensate drain line.
True or False
False
The secondary heat exchanger of a high efficient furnace can produce liquid carbonic acid.
True or False
True
A power drum humidifier should operate whenever the associated humidistat is closed, regardless of furnace operations.
True or False
False
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
b) The fan is mounted directly on the motor shaft
A sealed combustion chamber prevents already heated air from being used for combustion air
True or False
True
A hot surface igniter typically heats up to temperatures over 2000 Degrees Celsius
True or False
False
Another name for a high-efficiency furnace is:
a) conventional furnace
b) combustion furnace
c) condensing furnace
d) secondary furnace
c) condensing furnace
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
e) either a or b
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
b) flame to provide a current path
The heat recovery ventilator is electrically interlocked with the:
a) main blower
b) exhaust fans
c) combustion air blower
d) both a and b
d) both a and b
It is common for a mid-efficient furnace to have multiple high limit safety switches.
True or False
True
A dual stage burner valve will run the burner flame on a high setting if more heat is required.
True or False
True
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
d) all of the above
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
b) heat exchanger
The purge time adjustment for the combustion air blower is typically made by a DIP switch on the electronic control board.
True or False
False
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
d) both b and c
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
d) any of the above
Some manufactures call the secondary heat exchanger in a condensing furnace a:
a) condenser coil
b) evaporator coil
c) remote radiator
d) hot plate
a) condenser coil
The combustion air blower forces air directly into the:
a) heat exchanger
b) plenum
c) flue
d) cold air return duct
c) flue
