12″ x 12″ (30cm x 30cm) Medium Square Chimney Balloon


This Chimney Balloon is suitable for square or oblong chimneys 10″ – 13″  (25 x 33cm) by 10″ – 13″  (25 x 33cm), and round chimneys between 10 and 13 inches in diameter. If you’re not sure what size to get have a look at our sizing chart. It comes without a mouth inflation tube. If you have a pump for an airbed or suchlike you won’t need one, but otherwise please add a foot pump or mouth inflation tube to your order.

SKU: CBMS1212 Category:


The 12″ x 12″ Chimney Balloon will fit a range of chimney flues but you need an idea of the dimensions of your chimney in order to get the right size.

How does a Chimney Balloon work?

The Chimney Balloon works by abutting against four walls to hold itself in place. It is inflated with air so that it pushes against the chimney walls and effectively blocks all chimney draughts. There is a small gap in the corner to allow for ventilation, to avoid any issues with damp.

Where do you fit a 12″ x 12″ Chimney Balloon?

First of all you need to decide where it’s going to fit. It should be somewhere you can easily reach with the pump or mouth inflation tube. If you have a fireplace surround, and have to poke the chimney balloon through a narrow opening to get to the chimney, you may prefer to use a Chimney Sheep. These are designed to fit narrow gaps in fireplace surrounds, whereas the Chimney Balloon is designed to fit the chimney itself. If you need to fit it in the chimney a little higher than you can reach with the pump or mouth inflation tube then you can use the handgrip extension kit to fit it higher up.

How do you fit a Chimney Balloon? 

Make sure the tap is open and pump some air into the balloon so that it starts to inflate. Once you’ve got a bit of air into it, put it in position to inflate it fully.

While you’re inflating it make sure it’s correctly positioned. It will move a little to where the chimney is widest. Inflate until the balloon is gently firm but not drum-taut. Please don’t over-inflate it. Then close off the tap.

If you’ve used the mouth inflation tube then the balloon will contract a bit as it cools. Once the balloon has gone down a little, top it up some more. (Really, it’s a lot easier with a foot pump but it’s up to you). Make sure the hand-grip is hanging free without being pushed against any obstacles.

Hang the “Remember to Remove” tag somewhere where it is visible.