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

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

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 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

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

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 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

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

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

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

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

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

A chimney or pipe should extend at least ______ above the highest part of a roof

2'

Air mixed with the fuel prior to ignition is _______

Primary air