Chapter 41 Study Guide
When a direct spark ignition systems electrode and flame rod are packaged together, they provide what is known as ______ sensing
Remote
A burner that produces a solid flame along the top of its long, horizontal orifice is a _______ burner
Ribbon
If a gas furnace has a fuel air mixture with natural gas over 14%, the mixture is considered ______ for combustion
Rich
A flow switch that uses a large paddle to catch a draft to open or close its contacts is a ______ switch
Sail
Air that is added to a flame after ignition is _______
Secondary air
A burner that produces a series of individual flames along a row of horizontal orifices is a ________ burner
Slotted
Flame rollout is when a furnace's flame ______
Spills backward out of the burner
Gas radiant heating is primarily used for ______
Spot heating
Specially sized orifices attached to the gas manifold are ______
Spuds
Category III furnaces require venting made of _______
Stainless steel
Another term for present combustion is ______ combustion
Stoichiometric
The stack temperature in a condensing gas furnace should be ________
Under 140°f
Flame rectification is used for the primary purpose of _______
Verifying the presence of a pilot flame
Furnace gas pressure is usually measured in ______
in. WC
In gas-fired radiant heaters, about ________% of the heat energy is converted into radiant heat
50
Increasing a furnace's gas pressure can produce the following effects, except ________
A decrease of the flame temperature
Thermostatic draft regulators open when a bimetal element senses and reacts to the heat of _______
Flue gas
Category IV furnaces have a ______
Flue gas temperature less than 140°f
Which two functions does a combustion blower perform
It pre-purges the heat exchanger and exhausted the flue gases
If a gas furnace has a fuel-air mixture with natural gas below 4%, the mixture is considered _________ for combustion
Lean
A _______ flame indicates that gas velocity is faster than the speed the gas can burn
Lifting
A gas furnace that does not burn natural gas is most likely adjusted to burn _________
Liquified petroleum (LP) gas
A gas valve provides low-pressure gas to the _______
Manifold
A chimney or pipe should extend at least ______ above the highest part of a roof
2'
In some gas furnaces, a device consisting of an inverted opening in the flue that can operate to help prevent back pressure is known as the ___________
Air break
After an annual gas furnace inspection, the customer should be reminded to shut off the system and notify the technician if there are ______
All the above
Many combustion analyzers can be used to measure
All the above
The term ultimate carbon dioxide content refers to the specific amount of carbon dioxide by volume that is present in flue gas when the _______ to achieve complete combustion
Exact amount of air is supplied
The stack temperature in a noncondensing gas furnace should be _________
Between 325°f and 500°f
Proper combustion in a gas furnace is shown in a flame that burns the color _______
Blue
The sheet metal chamber where heat collects before being distributed is called the ______
Bonnet
Radiant gas heaters typically use elements made of _______
Ceramic
Flame rectification involves using the pilot flame to _______
Change a small electric current from ac to dc
The type of venting that is composed of masonry is ________
Class A
Type of venting that is composed of double-wall Metal is ________
Class B
The primary action performed by a rollout switch when it is actuated is to
Close the gas valve
A single unit that contains multiple components, such as a manual shutoff, adjustments, and a pressure regulator, is called a _______ gas valve
Combination
A gas furnace produces heat for distribution through _______
Combustion
On modern gas furnaces, the first device that begins operation on a call for heat is the _____
Combustion blower
The higher the efficiency of a gas furnace, the more likely it is to develop ________
Condensation
A hot-surface ignite reaches flame ignition temperature through ___________
Conduction of electrical current
A gas piping installation to a furnace or boiler should include a _______ to trap and collect possible contaminants that may flow with the gas
Drip leg
A gas furnace's ignition control module monitors several _____, which prevent the furnace from operating unless certain conditions are met
Electric interlocks
During normal operation, disadvantage that only a direct-spark ignition system can produce is _________
Electromagnetic interference
Which gas furnace device is very fragile, sensitive to vibration, and easily broken
Hot-surface igniter (glow coil)
The purpose of a standing pilot light is to _____
Ignite the gas burner flame
A single-port burner that directs the mixture of air and fuel gas through a large orifice to produce a large flame is a _______ burner
Inshot
Combustion blowers are used in _______
Mid-efficiency and high-efficiency furnaces
As the amount of excess air increases, ______
More heat is carried through the flue to the outdoors
On a gas furnace service call when measuring flame sensor rectification, use a _________
Multimeter
In low-efficiency gas furnaces, flue gases are moved outdoors by _________
Natural convection
An ignition control module has _______ if it closes the gas valve but not the pilot valve when the flame rod does not detect a flame
Non-100% shutoff
An intermittent-pilot ignition system burns and monitors its pilot light _________
Only while the thermostat is calling for heat
The important element that must be present in proper amounts and is consumed as it supports combustion is __________
Oxygen
Factors that affect pipe size in a gas piping installations include the following except _____
Piping material
A primary difference between non interfered ignition controls and integrated ignition control is the ability to ________
Preform self-diagnostic function
In a gas furnace application, a switch that connects to the end of a damper motor shaft is a ______ switch
Pressure
The primary variables that determine a furnace's venting classification are the _____ of the flue gas
Pressure and temperature
The gas supply to a gas furnace is maintained at a low pressure by the __________
Pressure regulator
If the gas burners are operating when the combustion blower is not operating, the ______ may be ruined
Pressure switch
Air mixed with the fuel prior to ignition is _______
Primary air
During normal system operation, a gas valve allows flow primarily when __________
The thermostat calls for heat
The safety device used in a standing pilot system to sense the pilot is a _________
Thermocouple