Although not unheard of, it is rare to find a modern home with an uncapped chimney. In addition to protecting your fireplace system from moisture, animals, and debris, chimney caps can also help improve fireplace drafting.
The presence of a chimney cap does not eliminate draft issues, however. There are a number of draft issues that can occur even with a chimney cap. Below are some of the most common chimney cap draft issues.
Draft-increasing chimney cap
While all chimney caps are designed to improve drafting, homes in areas with extreme winds may still experience downdrafts even if they have a chimney cap. If you notice downdrafts or smoke blowing back into your home on especially windy days, you may have this problem. When this happens, a special draft-increasing chimney cap may be needed.
Draft increasing chimney caps work by creating stronger updrafts. Designed to force wind around the top rather than down it, these chimney caps increase the air velocity and decrease static pressure around the chimney structure. Doing this forces the smoke upwards and out of the chimney while preventing the wind from drafting back down no matter what direction the wind is blowing.
Clogged chimney cap
Chimney caps are designed with mesh sides that help keep animals and debris out of the chimney structure. However, these same wire sides can become clogged on both the outside and the inside. Clogged chimney caps can create serious draft problems – as well as fire hazards – if the buildup of debris is not removed.
Inside the chimney, chimney caps commonly become clogged by excessive creosote buildup. This is often seen in homes that have not had their chimneys swept or inspected in several years. Creosote buildup is especially dangerous as it is a flammable substance; when accidentally ignited by a spark or ember, creosote is the leading cause of chimney fire.
In addition to creosote, chimney caps can also be clogged by debris such as leaves, twigs, roofing materials, and even stray Frisbees. Likewise, animals attempting to access the chimney or nesting under the chimney cap can cause blockages. When any portion of the chimney cap mesh is covered, the chimney may not be able to draft properly.
Improperly installed chimney cap
Another common cause of draft issues with chimney caps comes from improper installation. If a chimney cap was not properly installed, it can shift or become easily damaged over time. This can affect airflow and drafting. Likewise, a chimney cap that does not fit properly or is not sized correctly can also cause draft issues. If the chimney cap is too big or too small, the fireplace will not be able to draw in the right amount of air to force smoke and other byproducts of combustion up and out of the chimney. Likewise, improperly installed or fitted chimney caps can cause structural damage to the rest of the chimney structure.
Even if your fireplace system has a chimney cap, you may still experiencing drafting issues. If your fireplace is not drafting correctly, contact Pristine Sweeps today!