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Carbon Monoxide (CO) is a colourless, tasteless and odourless gas. It is known to be highly toxic, can cause severe illness and in the worst cases, death.  It is slightly lighter than air, however as the difference is small, in a contained environment such as a room in a house the gas will naturally diffuse evenly.

It is produced when there is not enough oxygen available in a fire to efficiently burn the fuel and since 1995 has been cited as the cause of over 700 deaths in the UK ( 


The lack of oxygen in a fire may be caused by limiting the airflow across the fire.  This could be caused by:

  • Having a restricted or even blocked chimney

  • Inadequate or blocked ventilation in the room

  • The vents on a stove/wood burner being closed

While your fire will be producing CO gas, in normal circumstances this and the other gases produced in the burning process will be vented out safely through your chimney.  However, if your chimney is compromised in any way or your appliance has not been properly maintained there is the chance for these gasses to leak back into the house and not necessarily the room where the fireplace is.

Having your chimney swept regularly will help prevent it from becoming blocked.  However, as shown above, having your chimney swept is only part of the story.  How your appliance or fireplace is maintained is equally important as well as how you manage your fires.

In addition, Van Dyke Sweeps include a service inspection of your fireplace or stove as standard when I sweep your chimney.  I will carry out any minor maintenance on the spot, free of charge, and will offer advice on the condition of your appliance.

While I will do my best to ensure your chimney and fire place is operating as safely as possible, I also strongly recommend that you have a Carbon Monoxide alarm fitted.


  • Get your chimney swept regularly

  • Have your appliance inspected annually and ensure it is well maintained

  • Never fully close the vents on your stove/wood burner

  • Ensure there is adequate ventilation in the room where the fireplace is

  • Fit a Carbon Monoxide alarm

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