Winter is fast approaching, and that means fireplace season. But don’t assume lighting a fire will warm up your house.
Unfortunately, you may end up cooler than when you started, since conventional fireplaces are notoriously inefficient sources of heat. In fact, most fireplaces take away more heat than they provide. The physics are simple: a fire needs oxygen to burn, which it draws from the surrounding air. In most cases, that means the fire is drawing in heated air from your house and sending it, along with some of its own radiant heat, up the chimney.
There are some things you can do to help improve the efficiency of your fireplace. If you have an older home, you probably have a freestanding masonry fireplace, meaning the fireplace rests on a foundation. If so, partially open a window in the room where the fireplace is located whenever you light a fire. That way, the fire will draw some fresh air from outside instead of taking air that is already heated from within the house. Modern freestanding masonry fireplaces are an improvement on older ones; the building code requires a fresh-air intake in the fireplace hearth, making it unnecessary to open a window.