In older homes, fireplaces often go unused or have a broken damper inside. An open fireplace is like having a small window open all day every day, so it's a good idea to have the damper repaired. But if the repair costs are too high, do the next best thing: Invest in a chimney balloon. This inflatable plastic pillow is made from a superstrong poly plastic that inflates and creates a tight seal inside your chimney. It's also reusable, so if you do have a working fireplace, you can easily deflate and reinflate it between fires.