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