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CHIMNEY INSPECTION DIAGNOSIS REPAIR
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CREOSOTE FIRE HAZARDS
Curved Brick Chimneys - Sulphation
Dead End Chimney Flue Hazards
Definitions of Chimney Types & Parts
DIRECT VENTS / SIDE WALL VENTS
DRAFT HOODS - gas fired
DRAFT MEASUREMENT, CHIMNEYS & FLUES
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FIRE CLEARANCES INDOORS
Fire Clearances for Masonry Chimneys
Fire Clearances for Metal Chimneys
FIRE CLEARANCES, Single-Wall Metal Flues
FIRE CLEARANCE WOOD & COAL STOVE FLUES
FIREPLACES & HEARTHS
FIRE STOPPING in BUILDINGS
FLAME COLOR, BLUE vs YELLOW COMBUSTION
FLASHING, CHIMNEY Mistakes & Leaks
FLUE SIZE SPECIFICATIONS
Flue Separation Requirements
Flue Tile Damage in Chimneys
Flue Vent Connectors - Boilers, Furnaces
Fuel Changes for Heating Appliances
HEATING COST FUEL & BTU Cost Table
HOME HEATING SAFETY
INDOOR AIR EMERGENCY RESPONSE
Lennox SAFETY WARNING
Metal Chimneys & Flues
Moisture / Frost Damaged Chimney
NOISE / SOUND DIAGNOSIS & CURE
ODORS & SMELLS DIAGNOSIS & CURE
ODORS FROM HEATING SYSTEMS
OIL HEAT SAFETY INSPECTIONS
PLASTIC HEATER VENTS
ROOF STAINS from CHIMNEYS
Safety Recalls, Chimneys, Vents, Heaters
Shared Chimney & Shared Flue Hazards
STAIN DIAGNOSIS on BUILDING EXTERIORS
STAINS on/near CHIMNEYS
Three-Sided Chimneys: Problems
Transite Pipe Chimneys & Flues
UNLINED FLUE INSPECTIONS
WOOD, COAL STOVES & FIREPLACES
WOOD STOVE SAFETY
Metal chimneys & flues for fireplaces: This article explains the use, requirements, installation and inspection of triple wall metal chimneys used for fireplace inserts and zero-clearance fireplaces. This article series on chimneys, chimney construction, and chimney safety provide detailed suggestions describing how to perform a thorough visual inspection of chimneys for safety and other defects. Chimney inspection methods and chimney repair methods are also discussed.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
Triple walled metal chimneys such as shown in Carson Dunlop's sketches are often used to vent "Zero-clearance" fireplace inserts.
The sketch at above right shows that the metal chimney may be permitted to run at angle of up to 60 deg. in some jurisdictions. If the angled chimney is constructed of masonry, such as a chimney lined with clay chimney tiles, see Mitering Angled Chimney Flues for notes on proper mitering of the flue liner tiles and other angled or sloped chimney concerns.
Fireplace inserts often are provided with steel spacers to force the installer to provide safe clearance from nearby wood framing or other combustibles.
As the sketch explains, an air-cooled or air-insulated triple wall chimney of this type is used only for zero-clearance fireplaces. If used to vent a wood stove the chimney is likely to be too cool, leading to a dangerous creosote build-up - a source of potentially fatal chimney fires.
"Zero Clearance" fireplaces and vents are usually not rated for literally zero clearance from combustibles, or greater fire clearance distances may be required by local or national fire safety codes.
If a homeowner converts a zero-clearance fireplace to a wood-stove hook-up the installation that uses a triple-wall metal chimney the installation is likely to be improper and dangerous.
Also remember to inspect zero-clearance fireplace installations to be sure that the clearance-projections are intact. We've found them hammered flat to cram a fireplace insert into a location where it did not fit - and was unsafe. Peer into cavities that vent room air around the fireplace or into openings around the fireplace to look at fire clearances wherever possible, or if in doubt, it may be necessary to cut an inspection opening into the adjoining wall.
This level of invasive inspection is a normal home inspection procedure but might be recommended as a further step in some circumstances such as where an installation was not inspected or where it has been performed by un-trained personnel.
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