15″ x 15″ (38cm x 38cm) Large Square Chimney Balloon


This versatile size is suitable for square or oblong flues that are 10″ – 18″ in either dimension (33cm x 38cm), or round flues up to 18″ in diameter. If you’re not sure what size to get have a look at our helpful sizing chart



The 15″ x 15″ Chimney Balloon comes without a mouth inflation tube – if you’ve got an airbed pump or suchlike then you won’t need one. If you haven’t got a pump then you’ll need to add a mouth inflation tube to your order.

Fitting a Chimney Balloon is like fitting double glazing in your chimney. It will keep cold air out, warm air in, and block out a lot of unwanted wind noise. We have lots of happy customers who report an immediate reduction in cold draughts once they’ve fitted one of our chimney draught excluders, and many even say they turn the thermostat down after fitting one. It’s astonishing how much warm air escapes up the chimney, and how much cold air comes down the chimney.

The 15″ x 15″ Chimney Balloon is a versatile size and will fit a wide range of chimney sizes. Just make sure it has four walls to abut against, within 10″ – 18″ (25cm – 41cm). It will also fit large round chimney openings.

It’s a little bit of a chore to measure your chimney but chimneys vary from the size of a bean can to the size of a door. It is not possible to have a universal chimney balloon size to fit every size. Do not waste your money on something that promises to be a one-size-fits-all because unless you have a standard chimney (in which case our medium balloon will be perfect for you!) then you will be disappointed. We also suggest that you don’t be tempted to buy a cheaply made PVC one either. They simply are not as safe as our tri-laminate plastic Chimney Balloons made in the UK by nice people at Watford.