NATE Gas Heat Exam Questions with Correct
Answers | Latest Update | Guaranteed Pass
Furnace efficiency is - CORRECT ANSWER -the difference between the heat input and the actual
heat output, expressed as a percentage
Furnace efficiency is calculated by - CORRECT ANSWER -useful output divided by input
Combustion efficiency is - CORRECT ANSWER -an index of the useful heat obtained from the gas
being burned
AFUE (Annual Fuel Utilization Efficiency) is - CORRECT ANSWER -a percentage of the annual
average efficiency of a furnace as determined by laboratory tests
All furnaces manufactured after what year must have an AFUE rating? - CORRECT ANSWER -
1985
All furnaces manufacturers after 1992 must have an AFUE of at least - CORRECT ANSWER -78%
Natural draft furnaces rely on the - CORRECT ANSWER -buoyancy of the hot combustion
products to create the draft needed to draw exhaust through the heat exchanger and out the
vent
It is difficult for natural draft furnaces to obtain a - CORRECT ANSWER -78% AFUE rating
Induced draft furnaces have an AFUE of at least - CORRECT ANSWER -78%
,Induced draft furnaces use - CORRECT ANSWER -an induced draft fan to draw the products of
combustion through the heat exchanger
An induced draft fan restricts - CORRECT ANSWER -the flow of warm air out the vent during the
off cycle
Condensing furnaces have an AFUE rating of at least - CORRECT ANSWER -90%
Condensing furnaces have an additional/ secondary - CORRECT ANSWER -Heat exchanger which
removes the latent from the flue gas by condensing the water vapor
The secondary heat exchanger is mounted directly over - CORRECT ANSWER -the discharge of
the blower
Condensed furnaces are designed for - CORRECT ANSWER -side wall venting or roof termination
Most condensing furnaces are designed to draw - CORRECT ANSWER -100% of combustion air
from outside
The induced draft motor pulls the hot flue games out of the - CORRECT ANSWER -first heat
exchanger then through the secondary heat exchanger
The four furnace configurations are - CORRECT ANSWER -up flow, down flow, horizontal left or
right, and multi-pose
Common types of fuels used on gas fired furnaces are - CORRECT ANSWER -natural (methane),
manufactured and mixed gases, and LPG (liquefied petroleum gas)
,Most furnaces are shipped to burn only one type of fuel but - CORRECT ANSWER -field
conversion kits may be available to convert to another type of fuel
Natural gas consists of approximately: - CORRECT ANSWER -90% methane (CH4), 5% Ethan
(C2H6), and 5% propane (C3H8)
Natural gas is formed from - CORRECT ANSWER -the remains of plants and animal life which
existed on the earth millions of years ago
Liquefied petroleum games are mainly - CORRECT ANSWER -propane or butane, sometimes a
mixture of the two
Liquefied petroleum games are obtained from - CORRECT ANSWER -natural gas orasabyproduct
from refining oil
Liquefied petroleum games are usually transported and stored in - CORRECT ANSWER -a liquid
form
Propane has a boiling point of - CORRECT ANSWER --44 degrees Fahrenheit
One cubic foot of propane requires - CORRECT ANSWER -24 cubic feet of air to support proper
combustion
Ignition temperature is the minimum temperature at which - CORRECT ANSWER -the
combustion reaction starts
Natural gas has an ignition temperature of approximately - CORRECT ANSWER -1170 degrees
Fahrenheit
, Propane has an ignition temperature of approximately - CORRECT ANSWER -932 degrees
Fahrenheit
Butane has an ignition temperature of approximately - CORRECT ANSWER -896 degrees
Fahrenheit
Specific gravity of gas is - CORRECT ANSWER -the weight of a given volume of a gas as compared
to an equal volume of dry air under standard pressure and temperature conditions
Dry air is used as a reference gas and it has a specific gravity of - CORRECT ANSWER -1
Any gas with a specific gravity less than 1 will be - CORRECT ANSWER -lighter than air
Any gas with a specific gravity higher than 1 will be - CORRECT ANSWER -heavier than air
The specific gravity of natural gas and manufactured/mixed gases is approximately - CORRECT
ANSWER -0.6 which makes it lighter than air
The specific gravity of liquefied petroleum gas is approximately - CORRECT ANSWER -1.52 which
makes it heavier than air
Care should be taken to avoid liquefied petroleum from - CORRECT ANSWER -pooling
Pressure - CORRECT ANSWER -the force per unit area exerted by a gas on the walls of a
container
Pressure is usually measured in - CORRECT ANSWER -inches of water column
Answers | Latest Update | Guaranteed Pass
Furnace efficiency is - CORRECT ANSWER -the difference between the heat input and the actual
heat output, expressed as a percentage
Furnace efficiency is calculated by - CORRECT ANSWER -useful output divided by input
Combustion efficiency is - CORRECT ANSWER -an index of the useful heat obtained from the gas
being burned
AFUE (Annual Fuel Utilization Efficiency) is - CORRECT ANSWER -a percentage of the annual
average efficiency of a furnace as determined by laboratory tests
All furnaces manufactured after what year must have an AFUE rating? - CORRECT ANSWER -
1985
All furnaces manufacturers after 1992 must have an AFUE of at least - CORRECT ANSWER -78%
Natural draft furnaces rely on the - CORRECT ANSWER -buoyancy of the hot combustion
products to create the draft needed to draw exhaust through the heat exchanger and out the
vent
It is difficult for natural draft furnaces to obtain a - CORRECT ANSWER -78% AFUE rating
Induced draft furnaces have an AFUE of at least - CORRECT ANSWER -78%
,Induced draft furnaces use - CORRECT ANSWER -an induced draft fan to draw the products of
combustion through the heat exchanger
An induced draft fan restricts - CORRECT ANSWER -the flow of warm air out the vent during the
off cycle
Condensing furnaces have an AFUE rating of at least - CORRECT ANSWER -90%
Condensing furnaces have an additional/ secondary - CORRECT ANSWER -Heat exchanger which
removes the latent from the flue gas by condensing the water vapor
The secondary heat exchanger is mounted directly over - CORRECT ANSWER -the discharge of
the blower
Condensed furnaces are designed for - CORRECT ANSWER -side wall venting or roof termination
Most condensing furnaces are designed to draw - CORRECT ANSWER -100% of combustion air
from outside
The induced draft motor pulls the hot flue games out of the - CORRECT ANSWER -first heat
exchanger then through the secondary heat exchanger
The four furnace configurations are - CORRECT ANSWER -up flow, down flow, horizontal left or
right, and multi-pose
Common types of fuels used on gas fired furnaces are - CORRECT ANSWER -natural (methane),
manufactured and mixed gases, and LPG (liquefied petroleum gas)
,Most furnaces are shipped to burn only one type of fuel but - CORRECT ANSWER -field
conversion kits may be available to convert to another type of fuel
Natural gas consists of approximately: - CORRECT ANSWER -90% methane (CH4), 5% Ethan
(C2H6), and 5% propane (C3H8)
Natural gas is formed from - CORRECT ANSWER -the remains of plants and animal life which
existed on the earth millions of years ago
Liquefied petroleum games are mainly - CORRECT ANSWER -propane or butane, sometimes a
mixture of the two
Liquefied petroleum games are obtained from - CORRECT ANSWER -natural gas orasabyproduct
from refining oil
Liquefied petroleum games are usually transported and stored in - CORRECT ANSWER -a liquid
form
Propane has a boiling point of - CORRECT ANSWER --44 degrees Fahrenheit
One cubic foot of propane requires - CORRECT ANSWER -24 cubic feet of air to support proper
combustion
Ignition temperature is the minimum temperature at which - CORRECT ANSWER -the
combustion reaction starts
Natural gas has an ignition temperature of approximately - CORRECT ANSWER -1170 degrees
Fahrenheit
, Propane has an ignition temperature of approximately - CORRECT ANSWER -932 degrees
Fahrenheit
Butane has an ignition temperature of approximately - CORRECT ANSWER -896 degrees
Fahrenheit
Specific gravity of gas is - CORRECT ANSWER -the weight of a given volume of a gas as compared
to an equal volume of dry air under standard pressure and temperature conditions
Dry air is used as a reference gas and it has a specific gravity of - CORRECT ANSWER -1
Any gas with a specific gravity less than 1 will be - CORRECT ANSWER -lighter than air
Any gas with a specific gravity higher than 1 will be - CORRECT ANSWER -heavier than air
The specific gravity of natural gas and manufactured/mixed gases is approximately - CORRECT
ANSWER -0.6 which makes it lighter than air
The specific gravity of liquefied petroleum gas is approximately - CORRECT ANSWER -1.52 which
makes it heavier than air
Care should be taken to avoid liquefied petroleum from - CORRECT ANSWER -pooling
Pressure - CORRECT ANSWER -the force per unit area exerted by a gas on the walls of a
container
Pressure is usually measured in - CORRECT ANSWER -inches of water column
