15″ x 36″ (38 x 91cm) Large Chimney Balloon


This large Chimney Balloon is suitable for flues that are 13″ – 20″ deep by 27″ – 36″ wide / 33 – 51cm deep by 69 – 91cm wide. If you’re not sure what size to get then please refer to our helpful sizing chart.

This comes without an inflation tube and being so big takes a lot of puff so it’s recommended you use a foot pump / stirrup pump for this one but if you prefer to use a mouth inflation tube then please remember to add it to your order.



The 15″ x 36″ Large Chimney Balloon is one of our most popular sizes. If you have a chimney this big then you will be feeling the cold, and you’ll certainly be noticing how much of your lovely warm air is rushing up the chimney. The Large Chimney Balloon is a cost effective means of blocking the flue and preventing the precious warm air from escaping. The Building Research Establishment state that 80 cubic metres of air travels up a chimney per hour. We don’t always notice this air escaping (though if you put your arm up your chimney you’ll feel it!) but the warm air must be replaced so it pulls in cold air from around doors, windows, keyholes, gaps around pipes etc, causing the cold draughts that we notice. Fitting a Chimney Balloon is like fitting double glazing in your chimney. It will effectively block the draughts, but also block out wind noise, and prevent debris and wildlife from getting in.

Is the 15″ x 36″ Chimney Balloon effective?

The Chimney Balloon has been tested by BSRIA and found to prevent 87% of airflow up the chimney. The Chimney Balloon has deliberately been designed with a small dimple in it to permit a restricted airflow in order to avoid chimney dampness. The seams are double-sealed for extra strength. Just make sure you insert it and remove it carefully. Although it is made of strong tri-laminate plastic, the larger chimneys that the 15″ x 36″ Chimney Balloon is designed to fit tend to be older ones with rougher surfaces, so it’s important to be gentle with the Chimney Balloon. If you’re not sure then you might want to consider a Chimney Sheep made by our sister company. It’s made of felted sheep wool so it’s very robust, but it costs a bit more.

The 15″ x 36″ Chimney Balloon will fit on one dimension but not quite reach on the other, will it still work?

No. The Chimney Balloon works by pushing against all four walls of the chimney. If it’s only pushing against two of them then it won’t hold itself in place properly and either it will fret against the sides and puncture, or there’s a risk of it being over inflated and bursting a seam. Although the name Chimney Balloon suggests it’s made of stretchy material it isn’t. It’s more stretchy than some of the PVC copies on the market, but that’s more to do with the ingenious rubber bands and the way they’re attached than the stretchiness of the tri-laminate material which really isn’t stretchy at all. So please don’t over inflate it hoping it will grow another couple of inches because it won’t. The 15″ x 36″ Chimney Balloon will actually fit a broad spectrum of chimneys but if it doesn’t match your chimney dimensions then get in touch about having a bespoke one made for you. Give us a call on 01900 817109 or drop us an email on info@chimneyballoon.co.uk.