Open fires are lovely and cosy in winter when they are alight but can provide a funnel for warm air on cooler days in the spring and autumn.

This can cause a cold draught to come down the chimney and into the room.
The chimney balloon is a simple but cleverly engineered device that can be inserted into the chimney and then inflated to fill the chimney but retaining a small gap for ventilation.  The chimney balloon can be left in the chimney until the fire is relit.

If you have any fireplaces that are not currently being used, then a chimney balloon can safely be left in situ for years preventing draughts and making your home cosier all year around.