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Block chimney draughts

A brick chimney and corrugated-iron roof against a blue sky with clouds

Chimney draughtsChimneys used with open fireplaces are designed to extract air from the house, whether or not a fire is burning. This means that your chimney can let a lot of air in and out of your home. Blocking the chimney when it isn’t being used will reduce the movement of air up and down your chimney and improve the comfort of your home.

Ways to block your chimney

Install dampers at the top or throat of your chimney

Chimney damper and balloonDampers can be closed when you are not using your fireplace, to prevent air from moving in and out of your home.

Install chimney balloons at the throat of your chimney

Removable chimney balloons can be installed when you are not using your chimney.

Seal the chimney with a tight-fitting screen

Installation of a removable screen is another option, but this will require some carpentry work.

What to do

Step 1: Safety first

Special care needs to be taken in houses with certain types of internal gas appliances, as they require fixed ventilation to expel the products of combustion from the home and operate safely.

Step 2: Check your chimney

Does your chimney already have a damper installed? This may seem like an obvious question, but dampers are installed out of sight so you may not be aware that it’s there. Look for a chain sitting just up inside the chimney or a lever/handle. Some dampers sit on top of the chimney and others are located in the 'throat' of the chimney. But if you can feel a draught coming down your chimney, chances are you don't have a damper.

Step 3: Install a damper or balloon

If you don't have a chimney damper you can either:

  • engage a professional to install a chimney damper or fitted screen 
  • install an inflatable chimney balloon yourself.

The chimney balloon should sit in the throat of the chimney and effectively seal off the flow of air. The shape and size of the balloon must be suitable for your specific chimney and needs to be installed correctly to achieve a good seal. Carefully follow the installation instructions provided with the chimney balloon.


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