Inserts are made from plate steel or cast iron and most have glass doors so you can see the flames. These appliances fit into the opening of the fireplace, with some models protruding onto the hearth. An insert which is extended out may be more efficient because the sides, top, and bottom provide additional radiant heat.
Masonry chimneys. When chimney fires occur in masonry chimneys, the 2100 degree temperatures, and the extreme pressure’s that result, often crack the terra cotta clay flue tiles which line the chimney. Chimney fires are NO ordinary fires! They frequently melt dampers and chimney caps, and can actually “melt” mortar! Flue tiles expand until they crack when subjected to such extreme temperatures. These cracks then provide a pathway for flame under intense pressure to reach the combustible wood frame of the house. Enough heat can also be conducted through a perfectly sound chimney to ignite nearby combustibles. Even if a first chimney fire doesn’t seem to have harmed a home, the structure may be so weakened that a second fire will burn it down.
In the past, most installers placed inserts in the fireplace without any chimney connections. This method, in some cases, allowed creosote to build up inside the fireplace, presenting a potential fire hazard. To prevent this, the National Fire Protection Association (NFPA) now requires that inserts be installed with at least (minimum) a positive connection to the chimney.
It is important to note that when relining an open hearth fireplace, a proper transition also constructed of stainless steel must be installed and sealed in the existing smoke chamber. Failure to properly install and seal this transition will result in smoke seeping to the outside of the liner carrying with it by products such as soot and creosote.
Inserts must have a connector between the appliance outlet and the first section of the flue liner. This sends the smoke and gases up and out of the chimney more directly, minimizing combustible deposits that condense in the fireplace. Most fireplace insert installations will benefit from a full relining of the chimney, because the smaller pipe size will provide a better draft as well as an added margin of safety.
Creosote is easy to identify as it is usually black in appearance. It can be the fine black dust called soot, (1st stage creosote); or porous and crunchy, (2nd stage: see photo on left); or it can be tar-like: drippy and sticky, until it hardens into a shiny glaze, (3rd stage). All forms of creosote can occur in one chimney system. Whatever form it takes, creosote is highly combustible. If it builds up in sufficient quantities – and ignites inside the chimney flue: the result is a volcanic chimney fire.
For a WETT inspection of your woodstove, fireplace, insert, pellet stove or space heater you can contact the WETT Inspector at www.wett-inspection.com to schedule an inspection. WETT inspections are provided to Barrie, Orillia, Midland, Penetang, Rama, Lagoon City, Newmarket, Bradford, Alliston, Angus, Everett, Thornton, Cookstown, Stayner, Innisfil, Lefroy, Alcona Beach, Wasaga Beach and most of Simcoe County. Your wood burning appliance will be inspected by a WETT Certified Inspector with over 7 years of WETT inspection experience.