Caring For Your Fireplace
The preservation of our environment is a major concern of many Americans. For years, environmentalists have been fighting for cleaner air and water by limiting pollution produced by big business and the automobile. Ironically, one of our country’s major contributors to poor air quality may be right in your own home the fireplace.
Recent studies by the Environmental Protection Agency show that woodsmoke (the smoke produced from burning wood in one’s fireplace) produces carbon monoxide, nitrogen dioxide and volatile organic compounds, pollutants that are potentially damaging to one’s health.
There are several steps you can take to reduce the threat that your fireplace may pose to the environment and at the same time improve its safety and efficiency.
The heating efficiency of a fireplace depends on two factors:
- how completely it burns the firewood (combustion efficiency) and
- how much of the fire’s heat gets into the room rather than going up the flue.
Greater combustion efficiency equals less pollution.Most fireplaces are not the most efficient heating devices. The average fireplace has a heating efficiency of about 10 percent. More simply stated, about 10 percent of the heat produced by the fire acts to heat the surrounding space.
The heating efficiency of a fireplace depends upon its construction or installation (in the case of modern prefabricated zero clearance metal units) and the way in which it is operated (what and how you burn in it).
Poor fireplace construction can reduce the amount of oxygen which fuels the fire (draft) and result in smoldering embers rather than a full-fledged fire. The draft is affected by several factors: the relationship between the volume of the fire box and the flue, the size and height of the chimney and the size of the fire box opening.
If the fireplace is producing more smoke than heat, the services of a masonry contractor or chimney sweep are needed. Frequently, one of these professionals will be able to make recommendations that will correct the condition.
One of the most critical elements of clean and efficient burning relates to the fuel. The fuel supply should consist of a mixture of:
- hardwoods, like maple or oak and
- softwoods, such as fir and pine.
When first starting your fire, use softwoods. They ignite easily and burn rapidly with a hot flame. Hardwoods provide a longer lasting fire and are best used after pre-heating the chimney. If hardwoods are unavailable, you can control your fire’s burn rate by using larger pieces of wood.One major mistake that most homeowners make is trying to burn wood that is too wet. Your best bet is to burn seasoned wood. The seasoning or drying process allows most of the natural moisture found in wood to evaporate, making it easier to burn. A properly seasoned log will have 20 to 30 percent moisture content.
Wood dries from the surface inward. Unsplit pieces dry very slowly. To properly season wood, split the logs as soon as possible and stack them in a dry spot for six to 18 months. Pile the wood loosely, allowing air to circulate through the split logs. Hardwoods take longer to dry than softwoods. Humidity and temperature levels also affect drying time.
Being choosy about what you burn will not only improve heating efficiency, but will help the environment too. Don’t burn garbage, treated or painted wood, plastic, or rubber. Each of these can produce potentially lethal fumes and may even contribute to a chimney fire. Even if you’re careful about what you burn, you’ll still need to be concerned about creosote buildup.
Creosote is a byproduct of wood burning and can build up on the cooler inside walls of the chimney. It is a volatile substance that can ignite and burn in the chimney, sometimes causing the chimney to explode and cause serious house fires.
It’s a good idea to have the fireplace inspected by a professional chimney sweep at least once annually. If you use your fireplace often during the heating season, the fireplace should be inspected once at the beginning of the season and again at the end.
Insulation and weather stripping can actually help the environment. Heated air is always escaping from your house, and is replaced by unheated outdoor air. The typical house has one-half to two air exchanges per hour, and more on windy or very cold days. If your house has little insulation and many air leaks, you are paying to heat the outdoors.
Some air exchange is necessary for proper combustion and because of the many sources of air pollution in the home (gas appliances, consumer products, cigarettes, etc.). And sufficient fresh air inlets are needed to replace air forced out of the house by exhaust fans, the dryer, furnace, water heater or wood fire. Otherwise “backdrafting” will suck polluted exhaust air in the appliance vents back into the home.