NFI Hearth Specialist questions and answers
with solutions
Air Infiltration - ANSWER typically, the passing of air into the house through small cracks or gaps
inherent to the structure. Affected by temperature difference between the inside and outside of
the structure, and air pressure factors (e.g., wind, the operation of solid fuel appliances or
electrical appliances such as fans).
Air Inlet - ANSWER the designed port(s) of entry for combustion air in a controlled combustion,
solid fuel burning appliance
Air Inlet Control - ANSWER the means by which the amount of air entering the air inlet is
regulated. Also referred to as air control
Air Supply - ANSWER broadly, the air that is supplied to the firebox of the wood burning
appliance
Air-to-fuel Ratio - ANSWER the ratio of air and fuel, by weight, in a solid fuel appliance. It should
be noted that 1 pound of dry air occupies a volume of 13.315 cubic feet at 70 degrees
Fahrenheit. Therefore, 35 pounds of air, the typical amount of air necessary to burn 1 pound of
wood in a fireplace, occupies 466 cubic feet.
Aldehydes - ANSWER class of compounds with distinct pungent odor, produced during
incomplete combustion of fuel gas
ANSI - ANSWER American National Standards Institute. The coordinating organization for
federated national standards system, consisting of 900 companies and 200 trade, technical,
professional, labor, and consumer organizations
Appliance - ANSWER a solid fuel burning product
,Appliance Regulator - ANSWER the appliance component, usually part of the combustion valve
that maintains constant gas pressure
Appliance to Fuel - ANSWER means of venting a solid fuel appliance (including fireplace inserts)
into masonry fireplace chimneys; the stainless steel connector passes from the appliance to the
first clay flue liner. Also referred to as direct connection
Approved - ANSWER acceptable to the authority having jurisdiction
Ash - ANSWER noncombustible solid byproduct of solid fuel combustion
Authority Having Jurisdiction (AHJ) - ANSWER The organization, office, or individual responsible
for "approving" equipment, materials, an installation, or a procedure
Automatic Gas Control Valve (combination valve) - ANSWER gas valve which combines control
functions; usually consists of gas manual valve assembly; pilot safety shutoff system, diaphragm
valve, gas pressure regulator, and valve operator
Baffle - ANSWER an obstructing device or partition in a solid fuel appliance, used to direct the
flow of gases and heat
Blower Door - ANSWER a diagnostic toll used to measure the tightness of buildings. Consists of
a calibrated fan for measuring airflow rate and a pressure sensing device to determine house
pressure levels
Breaching - ANSWER refers to the chimney connector access (hole) in a masonry chimney
, British Thermal Unit (BTU) - ANSWER a measure of heat energy; the amount of heat required to
raise the temperature of one pound of water one degree Fahrenheit at sea level
Burn Rate - ANSWER combustion rate, usually expressed in pounds of fuel consumed per hour
Butane - ANSWER a colorless, odorless, nontoxic gas; not generally used in hearth appliances
Bypass Damper - ANSWER term specifically referring to the movable plate in some catalytic
wood burning appliances that in one position channels the flue gases through the catalytic
combustor, and in one position channels the smoke to "bypass", or not go through, the catalytic
combustor. On some noncatalytic appliances, a movable plate that redirects and increases
residence time of gases
Can - ANSWER holder for catalytic combustor usually made of stainless steel
Canning System - ANSWER device surrounding catalytic combustor, usually consisting of
insulation mat and stainless steel can, or holder
Cap - ANSWER also termination cap. covering for factory built chimney that minimizes effect of
wind, and prevents entry of rain, snow, and debris
Carbon Dioxide (CO2) - ANSWER colorless, odorless noncombustible gas produced by the
complete combustion of carbonaceous fuel; is nontoxic
Carbon Monoxide (CO) - ANSWER colorless, odorless combustible, and toxic gas produced by
the incomplete combustion of carbonaceous fuel
with solutions
Air Infiltration - ANSWER typically, the passing of air into the house through small cracks or gaps
inherent to the structure. Affected by temperature difference between the inside and outside of
the structure, and air pressure factors (e.g., wind, the operation of solid fuel appliances or
electrical appliances such as fans).
Air Inlet - ANSWER the designed port(s) of entry for combustion air in a controlled combustion,
solid fuel burning appliance
Air Inlet Control - ANSWER the means by which the amount of air entering the air inlet is
regulated. Also referred to as air control
Air Supply - ANSWER broadly, the air that is supplied to the firebox of the wood burning
appliance
Air-to-fuel Ratio - ANSWER the ratio of air and fuel, by weight, in a solid fuel appliance. It should
be noted that 1 pound of dry air occupies a volume of 13.315 cubic feet at 70 degrees
Fahrenheit. Therefore, 35 pounds of air, the typical amount of air necessary to burn 1 pound of
wood in a fireplace, occupies 466 cubic feet.
Aldehydes - ANSWER class of compounds with distinct pungent odor, produced during
incomplete combustion of fuel gas
ANSI - ANSWER American National Standards Institute. The coordinating organization for
federated national standards system, consisting of 900 companies and 200 trade, technical,
professional, labor, and consumer organizations
Appliance - ANSWER a solid fuel burning product
,Appliance Regulator - ANSWER the appliance component, usually part of the combustion valve
that maintains constant gas pressure
Appliance to Fuel - ANSWER means of venting a solid fuel appliance (including fireplace inserts)
into masonry fireplace chimneys; the stainless steel connector passes from the appliance to the
first clay flue liner. Also referred to as direct connection
Approved - ANSWER acceptable to the authority having jurisdiction
Ash - ANSWER noncombustible solid byproduct of solid fuel combustion
Authority Having Jurisdiction (AHJ) - ANSWER The organization, office, or individual responsible
for "approving" equipment, materials, an installation, or a procedure
Automatic Gas Control Valve (combination valve) - ANSWER gas valve which combines control
functions; usually consists of gas manual valve assembly; pilot safety shutoff system, diaphragm
valve, gas pressure regulator, and valve operator
Baffle - ANSWER an obstructing device or partition in a solid fuel appliance, used to direct the
flow of gases and heat
Blower Door - ANSWER a diagnostic toll used to measure the tightness of buildings. Consists of
a calibrated fan for measuring airflow rate and a pressure sensing device to determine house
pressure levels
Breaching - ANSWER refers to the chimney connector access (hole) in a masonry chimney
, British Thermal Unit (BTU) - ANSWER a measure of heat energy; the amount of heat required to
raise the temperature of one pound of water one degree Fahrenheit at sea level
Burn Rate - ANSWER combustion rate, usually expressed in pounds of fuel consumed per hour
Butane - ANSWER a colorless, odorless, nontoxic gas; not generally used in hearth appliances
Bypass Damper - ANSWER term specifically referring to the movable plate in some catalytic
wood burning appliances that in one position channels the flue gases through the catalytic
combustor, and in one position channels the smoke to "bypass", or not go through, the catalytic
combustor. On some noncatalytic appliances, a movable plate that redirects and increases
residence time of gases
Can - ANSWER holder for catalytic combustor usually made of stainless steel
Canning System - ANSWER device surrounding catalytic combustor, usually consisting of
insulation mat and stainless steel can, or holder
Cap - ANSWER also termination cap. covering for factory built chimney that minimizes effect of
wind, and prevents entry of rain, snow, and debris
Carbon Dioxide (CO2) - ANSWER colorless, odorless noncombustible gas produced by the
complete combustion of carbonaceous fuel; is nontoxic
Carbon Monoxide (CO) - ANSWER colorless, odorless combustible, and toxic gas produced by
the incomplete combustion of carbonaceous fuel
