If your fireplace is not drawing well, you need to take steps to correct whatever is causing the problem. A badly drawing fireplace, or any other badly drawing fuel burning appliance, is a safety and maintenance hazard. If your fireplace does not draw well, it does not burn your firewood efficiently, so you get more creosote buildup inside your chimney, you waste money on fuel, you are likely to smell smoke inside your house. It is possible that you will get dangerous levels of carbon monoxide in your home.
If you have a fireplace that normally draws well, but you notice that it is getting smoky and you are having trouble keeping a hot fire going, there are a few obvious things you need to check before you seek outside help.
First, make sure your damper is fully open. You should have your damper closed when you are not using the fireplace in order to keep cold air from flowing down the chimney, and to keep squirrels, bats and birds out of your house. But, it is easy to forget to open the damper again when you want to start a fire. You can then carefully climb onto your roof and use a flashlight to check inside your flue. Make sure there are no animals or other obstructions such as bird nests or dry leaves inside your chimney. Also, notice if there is excessive soot and creosote buildup, either inside your flue or on the fire arrestor screening around your chimney cap, if you have one.
Once you eliminate physical obstructions and clean the inside of your flue, your fireplace should return to its normal efficient operation. Sometimes weather or wind can affect your chimney draft, especially when you first start a fire and the chimney liner is not heated up yet. If you have a fireplace or other appliance that has a chronic problem with poor drafting, then you should consult a chimney and fireplace specialist about things you might be able to do to improve the configuration of your system. A specialist may determine that the inside area of your flue is too small for the size of your fuel burning application, or that the length of your chimney is not optimum. Sometimes installing a flexible metal chimney liner in an unlined chimney will improve draft, as may installation of a wood burning insert into your fireplace. A metal chimney liner insulates the flue from the outside structure of the chimney, so combustion gases stay hotter on their way up, creating a stronger updraft than colder gases would.
If the costs involved in modifying a fireplace and flue are excessive, you may be able to adjust your fire managing routine to improve your fireplace’s drafting ability. In general, a small, hot fire will draw much better than a big, cold fire, and well seasoned wood will perform much better than green wood.