Chimney fires occur when the deposits of combustion are left within the flueways. By definition, a chimney fire is the burning of soot or creosote within the appliance, outlet or flue system, which can result in improper function of the appliance, damage to the flue, house or surrounding structures and it can even start a house fire.
Chimney fires are usually started when high temperatures or flames from a very hot fire extend into the appliance outlet or flue and the combustible deposits catch light.
This type of chimney fire can be sometimes associated with:
- A loud roaring noise, which occurs as massive amounts of air are sucked through the appliance or fireplace opening and used to oxidise the combustible fuels within the system
- Sparks and flames seen shooting from the chimney top, which can be firework like in appearance
- A glowing or shimmering appliance outlet or connector
- Vibrating appliance, outlet or connector
- Flames visible through any tiny cracks in the outlet or connector
- Smoke and odours noticeable in adjoining rooms or the loft space
- The heating up of the chimney breast or flue pipe, in the same room as the appliance and also other rooms that the flue passes through
Important! It should be noted that it is possible to experience a chimney fire without noticing any of the above characteristics; it is also possible that any combination of the above characteristics, will be noticed. As all chimney fires are different, the above characteristics are intended only as a useful guide.
All chimney fires are extremely dangerous even though their intensity and duration may vary. During a chimney fire, internal flue temperatures may reach a staggering 1,100 degrees Celsius. As a result, massive radiant heat is emitted through the chimney walls, and with the addition of possible thatched or wooden roofs, a devastating house fire can start quickly. Flames and sparks can leap from the chimney top or through cracks in the flue and ignite the roof and other parts of the house. The bricks of a chimney can become hot enough to combust nearby flammable materials such as thatch and wooden beams. Adjoining houses and nearby trees can also be affected.
If no apparent damage is visible on the exterior of the chimney breast or flue, it is still highly probable that damage may have occurred within the lining of the chimney. Chimney fires burn hot enough to damage liners, crack chimney walls and pots, and damage factory-built metal chimneys.