Glossary
Here are some words common to the chimney industry, and their definitions.
- Ash Dump
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That portion of the fireplace located at the rear of the firebox consisting of a hinged metal door for dumping ashes into the Ash Pit.
See it on our Chimney Diagram.
- Ash Pit
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That portion of the chimney located beneath the firebox, built into the foundation to provide a passageway or “pit” that ashes may be emptied into. Ashes are generally cleaned from the pit by way of the clean out door.
See it on our Chimney Diagram.
- Chim-Scan Video Scanning
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A video scan is where we use a camera system which is lowered into the chimney (or pushed up from the bottom). The camera allows us to inspect the chimney from a range of just a few inches instead of just looking from the top or bottom. The camera image is viewed on a TV monitor by the inspector. Video inspections may be recommended if the customer or sweep suspect certain problems. Video inspections are often recommended after a chimney fire or some other form of damage to a chimney, and are a routine part of a Level II or Level III inspection.
- Chimney Fire
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Chimney fires occur when combustible deposits (creosote) on the inner walls of the chimney ignite. A fire hazard exists if ¼″ of creosote (or more) coats the inner walls of the chimney. Failing to maintain your wood stove or fireplace properly can lead to a chimney fire.
- Clean Out Door
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That portion of the chimney located in the basement or at ground-level on the chimney exterior, used to remove creosote and other foreign matter from the chimney. The clean out door should be tightly sealed to prevent cool air from entering the chimney as this reduces proper drafting efficiency.
See it on our Chimney Diagram.
- Creosote
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Creosote is a flammable black deposit in chimneys that results from burning wood. It is often initially liquid, but may dry or pyrolyse to a flaky or solid form. Creosote removal is the most common reason for sweeping the chimney.
- Crown/Wash
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The crown (also called a wash) is the concrete portion of the chimney located at the top to help shed rain water. It can take the form of a sloped bed or a rectangular “formed & poured” shape. When the crown is cracked or deteriorated, rain can be absorbed into the chimney and cause rapid deterioration.
See it on our Chimney Diagram.
- Direct Connection
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Direct Connection refers to how a lining system is connected to a wood stove insert. A direct connection is a lining system extending from the wood stove to the bottom tile liner in the chimney (generally in the smoke chamber). While better than no pipe at all, this is an undesirable and dangerous connection as flue gases will condense to form creosote in the often oversized masonry flue. This connection is also very difficult to remove and re-install for chimney cleaning and/or servicing.
- Draft
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The difference in air pressure at the same elevation between the inside and the outside of a chimney, chimney connector, or appliance. The term draft is also sometimes used to denote the rate of combustion air flow into a fuel-burning appliance, or the rate of flue gas flow.
- Efflorescence
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Efflorescence is a white stain that appears on bricks. It is due to moisture problems mixing with chlorides. It is an unsightly stain that indicates a problem with the chimney taking on moisture. Most often seen on chimneys venting gas appliances and is an early sign of deterioration.
- Firebox
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The location in a fireplace where the fire is built and contained. The firebox is constructed on the inside of a special kind of brick manufactured for its refractory qualities and its ability to withstand high temperatures.
See it on our Chimney Diagram.
- Flue
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Any device used for containing and venting the products of combustion from gas, oil, or solid fuel appliances or fireplaces. Also, the inner part of a chimney that contains the products of combustion from gas, oil, or solid fuel appliances or fireplaces. Flues can be made of terra cotta clay tiles or metal.
See it on our Chimney Diagram.
- Hearth Extension
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The area directly in front of the opening of the fireplace usually constructed of masonry or other heat resistant material for the purpose of shielding the floor from excessive heat.
See it on our Chimney Diagram.
- Level I Inspection
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A Level I inspection is the recommended level when an evaluation of the chimney system for continued service is needed and the conditions of use are not changing. This could include:
- Routine or annual evaluations of the venting system
- An appliance connected to the system is being replaced with a similar appliance
- During chimney cleaning or sweeping
A Level I inspection is limited to readily accessible portions of the venting system, and accessible portions of the connected appliance(s) and the chimney connection. The inspector will check the readily accessible portions of the chimney, its enclosing structure, and the flue. A Level I inspection includes verification that the flue is not blocked or significantly restricted.
- Level II Inspection
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A Level II inspection is more detailed and thorough than a Level I inspection and is the recommended inspection when conditions of use for the appliance or venting system are changing, or when a Level I inspection reveals the need for a more detailed inspection. Several instances where a Level II inspection is specifically recommended include:
- Replacement of an appliance with one of dissimilar type, input rating or efficiency
- Prior to a flue relining
- Upon sale or transfer of the property
- After an event likely to have caused damage to the chimney, such as a chimney fire or other sudden occurrence event
A Level II inspection includes all of the requirements of a Level I inspection as well as the following:
- Inspection of accessible areas of attics, basements, and crawl spaces
- Accessible areas of the chimney exterior and interior
- Accessible portions of the appliance and chimney connection
- Video scanning, or other thorough inspection, of the flue interior
- Evaluation of the flue lining to determine that its material and sizing is appropriate for the appliances being served
- Proper clearance to combustibles in the accessible areas listed above
- Proper construction and condition of the chimney system in the accessible areas listed above
While the Level II inspection is a rather thorough inspection and requires access to many areas of the building, it does not require removal of permanent parts of the building, such as siding, chase covers or wall coverings.
- Level III Inspection
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A Level III inspection is the most detailed of all of the inspection types and includes inspection of concealed areas of the building. However, examination of concealed areas will be limited to areas reasonably suspected of containing hazards that cannot be evaluated otherwise.
A Level III inspection includes all areas covered in a Level I and Level II inspection, and inspection of concealed areas to investigate known or suspected problems. In as much as certain portions of a Level III inspection require destructive action to the building, the inspector will discuss these areas with the building owner prior to the inspection.
- Mantle
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That part of a hearth setting that protrudes from the surface above the opening of the fireplace and is usually used as a shelf. If made of combustible material, it must be far enough above the fireplace opening to meet NFPA standards.
See it on our Chimney Diagram.
- Parging
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Parging is a layer of masonry that covers another surface. It is applied with a trowel, and can have a variety surface finishes.
- Positive Connection
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Positive Connection refers to how a lining system is connected to a wood stove insert. A positive connection is a lining system extended from the wood stove to the top of the chimney. This is the preferred method of lining a wood stove insert, and is required by code in most applications.
- Scaling
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Scaling is a condition wherein clay tile flue liners chip or peel. This is most often due to moisture mixing with corrosive deposits. Scaling compromises the integrity of the chimney liner and its ability to contain chimney fumes.
- Smoke Chamber
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That portion of the fireplace located above the firebox and at the base of the chimney flue where smoke gathers before it is exhausted up and out of the chimney. Because smoke tends to linger in the smoke chamber, large deposits of creosote often accumulate here.
See it on our Chimney Diagram.
- Smoke Shelf
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The ledge or concave shaped portion of the fireplace located directly behind the throat of the fireplace, at the base of the smoke chamber. The smoke shelf collects rain water, debris, or anything else that may enter the chimney. Considerable creosote deposits generally collect here.
See it on our Chimney Diagram.
- Spalling
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Spalling is a condition wherein the face of a brick breaks or “pops” off. This is most often due to freeze/thaw cycles. There are certain types of brick more prone than others to experience spalling. Spalling compromises the integrity of the brick and its ability to repel/resist water penetration.
- Throat
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The narrow passage above the firebox, forward of the smoke shelf and below the smoke chamber, generally has a damper which must be opened before the fireplace is used, and may be closed, when the fireplace is not in use.
See it on our Chimney Diagram.
- Throat Damper
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Metal plate installed just above the firebox of a masonry chimney that are used for sealing the flue shut when the fireplace is not in use. Since they seal metal to metal, the seal is quite leaky even when the plates are new. Over time, the plates rust and deteriorate as they are exposed to heat and moisture. When this happens they lose almost their entire flue sealing capacity.
See it on our Chimney Diagram.
- Top-sealing Damper
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A device installed at the top of a chimney for the purpose of sealing the flue shut when the fireplace is not in use. They are often used as replacements for throat dampers that are installed just above the firebox when a masonry chimney is built. Lyemance and Lock-Top top-sealing dampers are as much as 90% more efficient than throat dampers because they provide a silicone rubber gasket seal rather than metal to metal.
- Tuck-pointing
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Tuck-pointing is a masonry term that refers to repair of the mortar joints between bricks. When this mortar has weakened or started to fall out, bricks may become loose. Tuck-pointing refers to installing new mortar between the bricks.
