NATE Gas Furnace Service Questions
and Answers| Latest Update
What precautions, if any, must be taken when installing a gas furnace on a wood platform in an
attic?, Use a zero clearance furnace or add a non-combustible base
A vertical vent in an induced draft non-condensing gas furnace that is oversized for its furnace
capacity will have what problem, if any? Excessive condensation in the vent
Primary air to an atmospheric burner is mixed with the gas within the: Venturi
During a maintenance check of a gas furnace ductwork should always be checked for:
Leaks and damages
What is the maximum acceptable supply voltage tolerance for a 120 V circuit? +/- 10%
What term is used to describe furnace efficiency? AFUE - Annual Fuel Utilization
Efficiency
In order to achieve complete combustion with natural gas, each cubic foot of gas must combine
with no less than ______ cubic feet of air with an additional 5 cubic feet of extra air to ensure
there is enough oxygen for complete combustion. 10 cubic feet
Primary air is air that: Is mixed with the fuel before the fuel reaches the burner
Secondary air is air that: Is mixed with the fuel at the burner after the fuel has ignited
Natural Gas & LP Gas have main line (delivery) pressures of ____ ? 14 in. w.g
, If the actual free area of a louvered door is not known, wood louvers are assumed to have a ___
% to ___ % free opening 20% to 25% free opening
If the actual free area of metal louvers or grilles are not known, they are assumed to have a ___
% to ___ % free opening 60% to 70% free opening
What are the 3 types of furnace ignition systems? Standing Pilot, Intermittent Ignition &
Direct Ignition
An induced draft furnace is generally ____% efficient (AFUE). 80%
A forced draft furnace is generally ____% efficient (AFUE) 90%
An induced draft furnace is what venting category? Category 1
A forced draft furnace is what venting category? Category 4
A gas appliance that is natural draft and has a draft hood is what venting category?
Category 1
If my return has -0.55" w.c. & my supply has +0.22" w.c what is the total static pressure?
0.77" w.c. total static pressure
What is the maximum face value of a supply register to avoid a drafty feeling? 600 FPM -
Feet Per Minute
How are air filters rated? The rating is known as MERV - Minimum Efficiency Reporting
Value
and Answers| Latest Update
What precautions, if any, must be taken when installing a gas furnace on a wood platform in an
attic?, Use a zero clearance furnace or add a non-combustible base
A vertical vent in an induced draft non-condensing gas furnace that is oversized for its furnace
capacity will have what problem, if any? Excessive condensation in the vent
Primary air to an atmospheric burner is mixed with the gas within the: Venturi
During a maintenance check of a gas furnace ductwork should always be checked for:
Leaks and damages
What is the maximum acceptable supply voltage tolerance for a 120 V circuit? +/- 10%
What term is used to describe furnace efficiency? AFUE - Annual Fuel Utilization
Efficiency
In order to achieve complete combustion with natural gas, each cubic foot of gas must combine
with no less than ______ cubic feet of air with an additional 5 cubic feet of extra air to ensure
there is enough oxygen for complete combustion. 10 cubic feet
Primary air is air that: Is mixed with the fuel before the fuel reaches the burner
Secondary air is air that: Is mixed with the fuel at the burner after the fuel has ignited
Natural Gas & LP Gas have main line (delivery) pressures of ____ ? 14 in. w.g
, If the actual free area of a louvered door is not known, wood louvers are assumed to have a ___
% to ___ % free opening 20% to 25% free opening
If the actual free area of metal louvers or grilles are not known, they are assumed to have a ___
% to ___ % free opening 60% to 70% free opening
What are the 3 types of furnace ignition systems? Standing Pilot, Intermittent Ignition &
Direct Ignition
An induced draft furnace is generally ____% efficient (AFUE). 80%
A forced draft furnace is generally ____% efficient (AFUE) 90%
An induced draft furnace is what venting category? Category 1
A forced draft furnace is what venting category? Category 4
A gas appliance that is natural draft and has a draft hood is what venting category?
Category 1
If my return has -0.55" w.c. & my supply has +0.22" w.c what is the total static pressure?
0.77" w.c. total static pressure
What is the maximum face value of a supply register to avoid a drafty feeling? 600 FPM -
Feet Per Minute
How are air filters rated? The rating is known as MERV - Minimum Efficiency Reporting
Value
