As home construction methods have advanced over the years, new homes are being built more air tight than ever before. Air tight homes are great for a household which utilizes a furnace or other method of heating besides open fire in a fireplace because a minimal amount of heated air will be lost through cracks along the edges of windows and doors of the home. However, fire requires not only fuel and heat to burn but also a steady supply of oxygen, and often times these new air tight homes will not permit enough outside air to be brought into the system so that the fire will burn in the fireplace as expected.
In cases such as these, we see folks who are experiencing smoking problems and even odor problems due to the how air tight their homes are. If the fire cannot get enough oxygen to burn the wood from either air in the home or an outside air source, it will actually draw air from outside down through the chimney, creating a down draft that will cause smoke and associated odors to enter the home. A down draft is generally not too difficult to diagnose or fix, but often times various factors play into the situation requiring multiple steps to be taken.
The most simple fix for this problem is to open a window or door near the fire a few inches so that the fire can be supplied by outside air and not need to draw air down the chimney in order for combustion to occur. This will help to keep the fire burning stronger and longer as well, but may not always be the only step that needs to be taken to correct a downdraft. With the help of a chimney professional, you may decide
that the height of your chimney is actually inadequate. A chimney that is not tall enough will not draw properly in the first place, and once the air tightness of a home is factored in, it is not surprising that so many people have down draft problems.
In this case there are two steps that can be taken because the ultimate solution is reconfiguring the ratio of flue size to firebox size. You can either decrease the size of the firebox by installing a Smoke Guard, which is essentially a metal strip that is easily installed to the top of the fireplace to “decrease” its dimensions, or increase the height of the chimney by a certain height that your chimney professional will determine. Turning off any fans or the furnace in your home may be another way to stop the downdraft. A down draft is tricky to fix without professional consultation due to the number of factors which can play into the problem.