A flue gas explosion occurs when built-up gases within the combustion chamber, flue pipe or chimney of a stove ignite suddenly, causing an explosion. The sudden release of energy in an explosion can result in fires and structural damage to the stove, chimney, and surrounding areas. Additionally, the exhaust of hot gases and soot/slag can cause severe burns or injuries to individuals nearby.

Flue gas explosions typically happen due to a combination of factors:

  • Poor ventilation: Inadequate draft or blockages in the chimney can cause gases like carbon monoxide to accumulate and ignite.
  • Creosote buildup: The accumulation of creosote, a highly flammable substance, on the walls of the flue pipe or chimney. 
  • Buildup of ash: The buildup of ash in the stove can lead to poor ignition and cause gases to form when the fuel cannot ignite.
  • High temperatures: Excessive temperatures within the stove or flue pipe due to overloading the stove with fuel or using improper fuel.
  • Faulty installation: Improper installation of the stove or chimney, leading to gas leaks or inefficient venting.
  • Failed ignition: If the combustible material in the stove fails to ignite, but instead is smoldering for some time after the ignition attempt, a sudden spark might cause the present gases to explode.

Prevention of flue gas explosions

To minimize the risk of a flue gas explosion, consider the following preventive measures:

  • Before burning: Clean the stove before attempting any ignition. Make sure the combustion chamber is free from ash and unburned fuel. Also make sure in pellet/hybrid stoves that the hole to the ignitor is clean. 
  • Regular maintenance: Schedule annual inspections and cleanings of your stove and chimney by a professional chimney sweep to remove creosote buildup. Make sure to get an annual service visit by an Aduro craftsman if you have a pellet or hybrid stove. 
  • Regular cleaning: Make sure to clean the stove regularly on your own and to remove ash and unburned pellets.
  • Proper ventilation and draft: Ensure proper draft by following guidelines for venting and using an appropriate chimney. If you suspect that the draft in the chimney is not sufficient, talk to your chimney sweeper and consider acquiring an Aduro DraftOptimizer.
  • Correct installation: Have your stove professionally installed according to local building codes and manufacturer instructions.
  • Quality fuel: Use dry, seasoned wood or appropriate fuel recommended for your stove to minimize creosote buildup. It is in general recommended to use high quality fuel, as it burns better thereby minimizing any risk. 

What to do if a flue gas explosion is expected

If you notice any signs of a potential issue, such as unusual odours, any buildup of smoke, or difficulty in maintaining a fire, take action!

Cease use: Stop using the stove immediately.

Ventilation: Open doors and windows for ventilation.

Contact a professional: Contact a qualified technician or chimney sweep to inspect and address the problem.