heating

what should a properly functioning flame rod measure

.8 microamps

in the sequece of operations what happens immediately after the flame ignites

.8 or greater flow through flame rectification circuit

on a two-stage furnce, what should the manifold pressure be during first stage heat

1.75wc

A cubic foot of natural gas requires approximately ___ cubic feet of air for complete combustion

10

electric furnaces and heaters are _____% efficient

100

Duct insulation is required when there is a ____ degree temp difference between the air inside the duct and the air outside the duct

15

what should a properly functioning thermocouple measure

18-30 dc microvolts

the smart valve uses _____ volts to energize a hot surface igniter

24

how many BTUs does one kilowatt produce

3413

what is the average efficiency of an permanent split capacitor

40-60%

what is the recommended humidity for a residential dwelling

40-60%

for air conditioning how many cfm are generally required per ton of cooling

400

first stage of a two stage system operates at what percentage

50-70%

What is the average efficiency of an electronically commutated motor

60-80%

standard hot surface ignition uses

80-120volts

What is a commutator

A device that converts AC to DC

A flame that is burning with heavy yellow tips is producing ________ _________

Carbon monoxide

The ______ forces air through the heat exchanger into the ductwork and then into the ductwork and then into the conditioned space

IBM

The _______ is the most common type of burner on induced draft furnaces

In shot

ECMs are programed by the ___,_____,_____ to meet the specific needs of their appliances

OEM

Which type of air purifier uses ultraviolet light and titanium oxide

PCO

on a call for heat the t stat switch between ___ and ___ closes

R and W

on a call for heat in an electric furnace which terminals are energized

R,W,G

the combination of the force pushing on the ductwork and the movement of the air

Total pressure

Which type of light effectively destroys biological contaminants such as mold and bacteria

Ultraviolet-c

Force generated by the movement and weight of the air

Velocity pressure

measures the speed of the air moving through the ductwork

Velometer

What kind of filter media effectively reduces household odors

activated carbon (charcoal)

in order to prevent a duct-mounted electric heater from being energized when the fan is not on an ____ _______ switch should be used

air proving

A high limit is usually a _______________ reset switch

automatic

________________ ______________ are used to balance the airflow throughout the duct system

balancing dampers

what is the most common cause of flame rollout

blowback

What are 70% and 80% efficient furnaces classified as

category 1

what are 90% + efficient furnaces classified as

category 4

The two types of return air duct systems are

central and individual

Fusible links and high limits are normally _________ switches

closed

which type of ecm is commonly used on a condenser fan

constant speed

what must be done to cause a furnace to attempt a relight after it has gone into a hard lockout

cycle the indoor disconnect switch (off for 5 seconds ,then back on

Uses an electrically powered igniter to light the main burner

direct burner

which furnace has a vertical air flow and the blower compartment located on the top of the unit

downflow

Dilution air enters through the _______ hood on a natural draft furnace or water heater

draft

What would happen if the fan on an electric unit heater failed and stopped blowing

either a or b are possible

electrostatic precipitators are also called ____________ air cleaners

electronic

in which system is the trunk duct longer,making the branch ducts shorter

extended plenum system

a _________ provides a mechanical means of catching suspended particles that pass through the air stream

filter

if 24v is present on the secondary side of the transformer but not a R and C what should be checked

fuse

Flame rollout switches are wired in series with the

gas vales

Three products of complete combustion of natural and LP gas are

heat, water vapor , and carbon dioxide

The undiluted flue gases from a condesing furnace have a _________ dew point and quickly condense

high

which furnace has a horizontal air flow through the heat exchanger and the blower compartment on one end

horizontal

a dirty flame rod ______ the flame rectification circuit

increases the resistance of

on a call for heat what must energize at the same time the first element does

indoor blower motor

Fresh air enters the structure through cracks and crevices by __________ or by ventilation from a fresh-air inlet

infiltrashion

A pilot flame that ignited just prior to the burners is called an __________ pilot

inturmitit

The diluted flue gases from a natural draft furnace have a _______ dew point and do not readily condense

low

which furnace has a vertical air flow through the heat exchanger and the blower compartment located on the side of the unit

low boy

measures the force of the air in the ductwork

manometer

A rollout is usually a ____________ reset switch

manual

what should the resistance of a functional heating element be

measurable resistance

Gas pressure is measured with a

menometer

ideally the best media filter would have the highest possible _______ rating while still allowing the proper amount of airflow through it

merv

also known as natural gas

methane

Atmospheric burners are used on ________ draft furnaces that dont have an inducer motor

natural

what are the resistive, heat emitting coils in an electric heater made out of

nichrome

A broken silicon carbide hot surface igniter can be replaced with a more durable version made out of silicon

nitride

which option best describes a flame rollout of high limit switch

normally closed, open on rise

which option best describes an air proving switch

normally open, close by negative pressure

On a wiring diagram the manufacturer uses ______ to communicate pertinent information about the equipment

notes

what must be done to cause a furnace to attempt a relight after it has gone into a soft lockout

nothing

When chemicals release vapors into the air the process is called _________

off gasing

Pressure switches and sail switches are normally __________

open

The air proving switch is a normally ______ switch that operates by ________ pressure in the heat exchanger

open negative

which system maintains a constant pressure at each outlet while heating the slab floor

perimeter loop

in which system do the branch ducts attach directly to the supply plenum

plenum system

An electrostatic precipitator uses a ________ charged wire and ______ charged plates to remove fine suspended particles from the air

positive negative

what is the only good way to determine if an IFC board has failed

power going in/ power coming out

in the sequence of operations what happens immediately before the gas valve energizes

pressure switch closes proving draft

The air that is drawn into the burner with the fuel, for the purpose of combustion is called ______________ air

primary

in which system does the trunk duct change size to amintain pressure and velocity

reducing plenum system

At startup an ECM may _____ back and forth before turning

rock

the air that is drawn into the combustion chamber with the flame to support combustion is called____________ air

secondary

A switch with a set of contacts actuated by a bimetal heat motor is called a ____________

sequencer

which low voltage control is used to energize multiple elements in stages

sequencer

a properly burning gas flame should be

sharp and blue with slight orange tips

Flexible duct runs should be kept as _____ as possible

short

what type of control allows water to flow into a humidifier

solenoid

how is the pilot ignited on a intermittent pilot system

spark

Force pushing outward on the walls of the duct system

static pressure

A modulating furnace raises or lowers the BTU output in increments called

steps

what controls the speed of an ECM

the low voltage signal

if a standing pilot will not stay lit either the ____________ or the ____ ________ has failed

thermocouple or the gas valve

Devices called___________ _______ reduce turbulence as the air flows around corners in the ductwork

turning vanes

the high voltage direct current flowing through the windings creates the magnetic force that ____ the motor

turns

which furnace has a vertical air flow through the heat exhanger and the blower compartment beneath the heat exchanger

upflow

which of the following is not true about an inducer fan

uses a 24 volt motor

the Ohm's law calculation for power is _______x_______

volts x amps

a constant _________ ECM will deliver the same amount of CFM even when the static pressure changes

volume

what is the unit of measurement for pressure in a duct system

wc

when does a limit switch de-energize the electric heat

when there is a high temp