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Solid Fuel Appliance Safety: Q&A on Installation and Regulations, Exams of Safety and Fire Engineering

A series of questions and answers related to the installation and safety of solid fuel appliances, such as wood stoves and fireplaces. It covers topics including required clearances, chimney construction, combustion efficiency, and regulatory standards. The content is presented in a question-and-answer format, making it useful for quick review and self-testing. It includes information on topics such as chimney connector clearances, hearth extensions, and combustion byproducts. The document also touches on epa regulations and best practices for efficient and safe operation of solid fuel appliances. It is designed to help professionals and homeowners understand and comply with safety standards.

Typology: Exams

2024/2025

Available from 05/31/2025

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Wood NFI
Solid fuel appliances with legs 6 inches or longer, floor protection
must consist of____________________. - Correct Answer โœ” โœ”
Closely spaced masonry units of brick, concrete, or stone that
provide a thickness of not less than 2", and covered with (24) gauge or
thicker sheet metal.
NFPA 211 requires that at least ________ inch of open, ventilated
airspace be provided between a single-wall connector that passes
through a masonry wall used as a wall shield and the masonry. -
Correct Answer โœ” โœ” 1/2
Name the 2 appliance design improvements that have increased
efficiency and reductions in emissions. - Correct Answer โœ” โœ” 1.
Catalytic combustor technology
2. Non-catalytic internal appliance design.
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Wood NFI

Solid fuel appliances with legs 6 inches or longer, floor protection must consist of____________________. - Correct Answer โœ” โœ” Closely spaced masonry units of brick, concrete, or stone that provide a thickness of not less than 2", and covered with (24) gauge or thicker sheet metal.

NFPA 211 requires that at least ________ inch of open, ventilated airspace be provided between a single-wall connector that passes through a masonry wall used as a wall shield and the masonry. - Correct Answer โœ” โœ” 1/

Name the 2 appliance design improvements that have increased efficiency and reductions in emissions. - Correct Answer โœ” โœ” 1. Catalytic combustor technology

  1. Non-catalytic internal appliance design.

Gas log sets that use a FBF for exhaust combustion by-products must be listed to? - Correct Answer โœ” โœ” ANSI Z21.60 Decorative Gas Appliance's for installation in solid-fuel appliances.

True or False Thermostats are prohibited for use with vented gas logs.

  • Correct Answer โœ” โœ” True

True or False; A fire screen must be in place during use of a vented gas log set? - Correct Answer โœ” โœ” True

According to ANSI Z21.50 vented gas logs must be equipped with __________ - Correct Answer โœ” โœ” an automatic gas ignition shutoff system.

A long run for a chimney connector is generally defined as - Correct Answer โœ” โœ” more than 6-8 ft

If off set elbows must be used on a connector it is recommended to have the elbows__________________________ - Correct Answer โœ”

โœ” As close to the chimney as possible.

The national regulations did not apply to appliances with: - Correct Answer โœ” โœ” - burn rates grater 5kg/hr (11lbs of wood)

  • air-to flue ratio > 35 to 1
  • firebox > 20 cubic feet
  • weight > 800kg or 1760lbs

-coal

-open wood burning

  • solid fuel furnaces & boilers
  • large industrial and commercial wood fired appliances

Tests showed that these regulations from the 80's showed that - Correct Answer โœ” โœ” Emissions from certified appliances were 6kg/hr a reduction of 85%

May 2015 revised EPA regulations step 1 - Correct Answer โœ” โœ” - wood, pellet stoves = 4.5gram per hour limit

  • Hydronic heaters have a 0.32 lbs per million BTU limit
  • Forced air furnaces 0.93lbs per hour limit

May 15 2020 regulations for wood and pellet stoves - Correct Answer โœ” โœ” - 2 grams per/hr crib wood

  • 2.5 grams per/hr cordwood

Stages of solid fuel combustion - Correct Answer โœ” โœ” 1. Moisture Evaporation > 212F

  1. Release of combustible gases > 500F
  2. Ignition and combustion of vapors and gases 540-1,225F
  3. Char burning > 900F

How much water is produced for each pound of wood burned. - Correct Answer โœ” โœ” 1/2 lb

At 100% combustion efficiency what byproducts would be produced - Correct Answer โœ” โœ” - Water vapor

Chimney connector reduced clearances with wall and ceiling protection:

24 gauge sheet metal over 1" glass fiber or mineral batts reinforced with wire, or equivalent on rear face, with at least 1" ventilated airspace

Max clearance reduction Wall & Ceiling

Min allowed clearance Wall & Ceiling - Correct Answer โœ” โœ” Max Wall & Ceiling = 66% / 50% Min allowed = 6"/9"

Chimney connector reduced clearances with wall and ceiling protection:

3 1/2 " thick masonry wall with ventilated airspace:

Max clearance reduction Wall & Ceiling

Min allowed clearance Wall & Ceiling - Correct Answer โœ” โœ” Max Wall & Ceiling = 66% / โ€” Min allowed = 6"/ โ€”

Chimney connector reduced clearances with wall and ceiling protection:

1/2" thick noncombustible insulation board over 1" glass fiber or mineral wool batts without ventilated airspace.

Max clearance reduction Wall & Ceiling

Min allowed clearance Wall & Ceiling - Correct Answer โœ” โœ” Max Wall & Ceiling = 50% / 33%. Min allowed = 9" / 12"

Chimney connector reduced clearances with wall and ceiling protection:

24 gauge sheet metal with at least 1" of ventilated airspace

Max clearance reduction Wall & Ceiling

Min allowed clearance Wall & Ceiling - Correct Answer โœ” โœ” Max Wall & Ceiling = 66% / 50% Min allowed = 6"/ 9"

3 1/2" masonry wall no ventilation, as wall protector / as ceiling protector - Correct Answer โœ” โœ” 33 1/3% / โ€”โ€”โ€”โ€”

Maximum allowable clearance reduction from appliances (listed & unlisted)

3 1/2" masonry wall spaced out 1" as wall protector / as ceiling protector - Correct Answer โœ” โœ” 66 2/3% / โ€”โ€”โ€”โ€”

Maximum allowable clearance reduction from appliances (listed & unlisted)

1/2" noncombustible insulation board over 1" glass fiber or mineral wool batts no ventilation, as wall protector , as ceiling protector - Correct Answer โœ” โœ” 50% / 33 1/3%

Maximum allowable clearance reduction from appliances (listed & unlisted)

Minimum 24 gauge sheet metal spaced out 1", as wall protector , as ceiling protector - Correct Answer โœ” โœ” 66 2/3% / 50%

Maximum allowable clearance reduction from appliances (listed & unlisted)

1/2" noncombustible insulation board over spaced out 1", as wall protector , as ceiling protector - Correct Answer โœ” โœ” 66 2/3% / 50%

Maximum allowed clearance reduction from appliance. ( Listed prefabricated systems) - Correct Answer โœ” โœ” Per manufactures instructions.

After reduction of listed clearances from appliances, clearances shall not be less than - Correct Answer โœ” โœ” 12"

UL 1618 Wall protectors, Floor protectors and hearth extinctions does not allow wall protectors to reduce listed appliance clearances to less than ___________" - Correct Answer โœ” โœ” 12

NFPA 211 requires a minimum of __________ inches clearance to combustibles for unlisted woodstoves - Correct Answer โœ” โœ” 36

the net free area of the outlet of the flue that it serves. - Correct Answer โœ” โœ” 4

A wythe or partition should be constructed of at least ____________" (nominal) thick solid masonry. - Correct Answer โœ” โœ” 4

An interior chimney requires a minimum ____________ inch clearance to combustible material - Correct Answer โœ” โœ” 2

Concerning interior masonry chimneys: Firestopping with a noncombustible sheet material no greater than __________inch thick, or galvanized steel not less than ______________gague must be installed at every floor and ceiling through which the chimney passes.

  • Correct Answer โœ” โœ” 1/2 , 26

Interior chimney - Correct Answer โœ” โœ” One that has any portion of the chimney within the exterior wall of the building.

Exterior chimney - Correct Answer โœ” โœ” Is defined as one that has the entire chimney completely outside the exterior wall of the chimney.

An exterior chimney requires a minimum ________________ inch clearance to combustible material. - Correct Answer โœ” โœ” 1

Thimble - Correct Answer โœ” โœ” Is a lining for the opening from the room into the chimney, into which the chimney connector is inserted. Also called a breaching..

Thimbles should be constructed by flue liners not less than - ______________inch thick, galvanized sheet metal of_______________ gauge minimum thickness, or noncombustible sheet material not more than __________ inch thick - Correct Answer โœ” โœ” 5/8, 24, 1/

UL 1777 liners suitable for use with closed chamber solid fuel hearth appliances are tested to sustained temperatures of _____________

What is the primary function of a Catalyst - Correct Answer โœ” โœ” To convert unburned hydrocarbons and CO to compounds that ignite at lower temperatures.

Conditions that reduce the effective surface area of a catalyst are? - Correct Answer โœ” โœ” โ€ข plugging

**- masking

  • peeling
  • substrate deterioration**

Masking - Correct Answer โœ” โœ” When the combustor becomes coated with carbon from low oxygen use and/or fly ash.

Peeling - Correct Answer โœ” โœ” Extreme temperatures (over 1800F) or flame impingement can cause the cells to peel away from the substrate of a catalytic combustor.

Substrate deterioration. - Correct Answer โœ” โœ” Damage to a combustor from...

**- thermal shock

  • mishandling
  • excessive draft.**

Name the 2 types of firebrick in wood stoves and their characteristics.

  • Correct Answer โœ” โœ” โ€ข Pumice - Light and high insulating capabilities - Fire clay - heavy and low insulating capabilities.

General guidelines for Minimum and Maximum draft for a wood stove

  • Correct Answer โœ” โœ” Min = - 0.5-0.

Max = + .10 -.

Minimum clearance for unprotected single wall connector is? - Correct Answer โœ” โœ” 18"

The Small crimped end of the chimney connector should be pointed down because? - Correct Answer โœ” โœ” This method contains solid and liquid materials inside the connector.

According to NFPA 211, a masonry wall constructed directly against a combustible wall can reduce appliance clearances by no more than? - Correct Answer โœ” โœ” 33%

Define an interior chimney? - Correct Answer โœ” โœ” A chimney which has "any portion of the chimney within the the exterior wall of the building".

An exterior chimney must be constructed - Correct Answer โœ” โœ” Completely outside the exterior wall.

Interior chimneys have a _______" C2C and exterior chimney have a ________" C2C - Correct Answer โœ” โœ” 2", 1"

Minimum C2C for an unlisted appliance - Correct Answer โœ” โœ” 36"

k-value indicates - Correct Answer โœ” โœ” The amount of heat (in BTUs) that will flow in one hour through one sq foot of a uniform material one-inch thick for each degree (F) of temperature difference from one side to the other.

R-value - Correct Answer โœ” โœ” Is a measure of a materials resistance to heat transfer.

Formula for converting k to R - Correct Answer โœ” โœ” R = (1/k) x inches of thickness

Formula for determining k-value - Correct Answer โœ” โœ” (BTU) (inch)

โ€”โ€”โ€”โ€”โ€”โ€”โ€”

(foot)squared (hour) (F)

What conditions promote creosote buildup; (incomplete combustion)

  • Correct Answer โœ” โœ” โ€ข Combustion zone temperatures below gas ignition points.