Whether you own a period property that houses original fireplaces or a new build with a sleek log burner, the idea of cosying up to watch a film with a roaring fire and a blanket seems idyllic.

But while such a feature is nice to have, heat can be lost up a chimney, just as it can dissipate through the roof, walls and floors of your home. In fact, chimneys are designed to draw air out and expel it outside. This is so, when you light a fire, the smoke can be carried outside rather than blown into your home. However, when a fire isn’t lit, warm air that’s created by your heating system can be lost via the chimney. This could reduce the efficiency of your home and potentially cause an increase in your heating bills as your boiler has to work harder to replace the heat that’s being lost.

With all of this in mind, you may be thinking about blocking up or sealing your fireplace, either temporarily if you don’t light it that often or permanently. 

How to seal a chimney

There are a few ways to seal up a chimney to reduce the amount of heat that is lost up it. You can find some of the easiest methods below that you can do yourself.

  • Install a sheep’s wool draught excluder

One easy and sustainable solution is to install a sheep’s wool draught excluder. These come in both rectangular and circular shapes and in a range of sizes to fit any chimney. They’re a kind of wool pad with a handle on one side so that they can be placed just inside the chimney. When sized correctly, they should be able to hold themselves in place without any additional help. Should you want to use the fire, the draught excluder can simply be removed and replaced again when you need it. This makes it a really good, sustainable and easy solution to keep the heat in your home.

  • Have a chimney balloon installed

Chimney balloons, also known as chimney pillows and flue blockers, are just another way to seal up your chimney to prevent heat from escaping. However, one of the benefits of using a balloon is that your chimney breast can still breathe, preventing damp and mould.

How does a chimney balloon work?

A chimney balloon is made from thick plastic and can be inserted up the chimney before being inflated. This means that, unlike the draught excluder, you can control how big you want the balloon to be so that it can suitably stop heat from escaping while also allowing a little airflow through for ventilation to prevent dampness and mould. Balloons do come in different sizes, so you should make sure that you’ve purchased the right size before inflating it.

The balloon can be kept in place for as long as you wish, however it should be removed before lighting a fire. As it’s made from plastic, it could melt, which wouldn’t make for a pleasant experience. 

How to inflate a chimney balloon

Once the balloon has been inserted into the chimney, it needs to be inflated. The balloon should come with a long tube that can be connected with a valve. As you blow into this tube, you should begin to see the balloon inflate. You can continue to blow air in until you’re happy with the balloon’s size and that it’s secure.

  • Use rigid foam

An alternative to sheep’s wool is rigid foam. This insulation board can be cut to size and fitted to your fireplace in the same way as a draught excluder.

To start with, measure the chimney opening and use a pencil to mark this out on your insulation board. Remember, it’s better for the board to be slightly too big for a tight fit, otherwise it may fall out or allow the warm air to escape, rendering it useless.

Once your shape is drawn on the foam, use a knife or saw to carefully cut the excess board away.

Finally, place the rigid roam into the chimney opening, ensuring that there are no large gaps and that the board is tightly wedged in. This might be seen as a more permanent solution. Unlike the sheep’s wool draught excluder, the foam might not be so easy to remove, and so you should ensure that you won’t be using the fireplace before installing.

Sources:

https://www.adventuresindiy.com/conservation/sealing-a-drafty-fireplace
https://dengarden.com/home-improvement/How-to-seal-an-unused-fireplace-and-save-on-heating-bills
https://www.giynow.com/2016/11/28/stop-loosing-heat-through-your-chimneys/ 

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