A wood fire can give your home a warm, cozy feeling, and in some cases can save you money. It can also affect air quality both indoors and out.
In many parts of Massachusetts, smoke from wood burning is a significant contributor to air pollution. Wood smoke contains carbon monoxide, smog-causing nitrogen oxides, soot, fine particles, and a range of other chemicals and gases that can cause or worsen serious health problems, particularly among children, pregnant women, and people with breathing difficulties.
Fireplaces, indoor wood stoves, and other indoor wood-burning appliances can also bring harmful pollutants into your home if they are improperly installed, are loaded with too much fuel, have back drafts, or vent to chimneys or stovepipes that are cracked or in disrepair. Proper installation, operation, and venting to the outside are important.
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Some towns and cities use zoning and other laws to impose restrictions on wood-burning appliances. Some ban or limit them in new construction. All local fire departments and boards of health in Massachusetts have the authority to regulate outdoor burning and the nuisance conditions that can result.
Department of Environmental Protection (MassDEP) regulations limit visible smoke ("opacity") and prohibit air pollution that places people at risk, interferes with property uses, threatens natural resources, or creates nuisances, such as excessive odor and soot. MassDEP also specifically regulates the sale, installation, and operation of outdoor hydronic heaters (wood-fired boilers).
At the federal level, the U.S. Environmental Protection Agency (EPA) in 2015 updated emission standards and certification criteria for residential wood heaters. The new regulations strengthen the emissions standards for new woodstoves, and set the first federal air standards for several other types of wood heaters:
- Pellet stoves,
- Indoor and outdoor wood-fired hydronic heaters,
- Wood-burning forced-air furnaces, and
- A type of previously unregulated woodstove known as a “single burn-rate” stove.
The rules required manufacturers to make their wood heaters less polluting starting in 2015 and to produce even cleaner models by 2020.
Wood heaters sold at retail in the United States now must have a permanent label indicating they are certified to meet emission limits in the rule, signaling to consumers that the heaters meet EPA’s standards. The rule also requires manufacturer efficiency and carbon monoxide testing and reporting, which will provide consumers additional information to help them select the best wood heater for their homes.
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Choosing the Right Equipment
There are many different types of wood-burning appliances on the market. Whether you are buying one for the first time or want to upgrade from one you already own, choosing the right equipment can make a positive difference for the environment, indoor air quality for you and your family, and your home heating budget.
Since 1988, all indoor wood stoves and fireplace inserts sold in the United States have been subject to EPA emission standards, which in 2015 the agency updated and expanded in scope. EPA-certified units feature baffles or dampers and secondary combustion chambers or air supplies to improve combustion efficiency and reduce emissions. They use less wood to produce the same amount of heat, saving you money while reducing air pollution.
If you own a pre-1988 indoor wood stove, fireplace insert, or other wood-burning appliance, you can significantly reduce its emissions by adding a catalytic combustor or converter. Doing this will help burn gases, fine particles, and soot before they are vented outside, for a cleaner, more efficient wood fire. Catalytic units should be inspected at least twice per year, both before and during peak home heating season.
The cleanest option is to replace your old wood stove with a new wood-burning appliance that meets EPA’s 2015 wood heater regulations. The Massachusetts Clean Energy Center (MassCEC) periodically offers financial incentives to homeowners for replacing old wood stoves with newer, more efficient units.
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Outdoor Wood-Fired Boilers
Outdoor hydronic heaters (wood-fired boilers) are typically located in small, insulated sheds that burn wood to heat water, which is then piped underground to provide heat and hot water to occupied buildings.
Outdoor wood-fired boilers can be more polluting and less efficient than other home heating technologies. Research by the State of New York has found that even when used properly, one of these units can emit as much fine particle pollution as:
- 12 EPA-certified indoor wood stoves
- 1,000 homes with oil heat
- 1,800 homes with natural gas heat
Improperly located and operated outdoor wood-fired boilers create heavy smoke and release it close to the ground, where it lingers and can expose everyone in the area to nuisance conditions and health risks.
These units are designed to burn dry, seasoned wood.Using them to burn green wood generates much more smoke.
Under the MassDEP Wood-Fired Boiler Regulation (see below):
- Only units that meet EPA emission standards and whose manufacturers have filed compliance certifications may be sold for installation in Massachusetts.
- New units must be located minimum distances away from property lines and neighbors' dwellings.
- All units need to meet minimum smokestack height requirements, burn only clean seasoned wood, and cause no nuisances or conditions of air pollution.
The regulation authorizes towns and cities - through their building, health, police, and fire departments - to enforce specific provisions. Some municipalities have enacted by-laws or ordinances that prohibit or limit the use of outdoor wood-fired boilers.
MassDEP and local boards of health can take enforcement actions in cases of excessive odor or smoke. Sometimes the only way to resolve complaints is for the owner of a unit to stop using it permanently.
If you are thinking about buying an outdoor wood-fired boiler:
- Confirm that it is legal to install and operate one in your community,
- Ask local officials about any specific restrictions you need to know about, and
- Consider the impacts an outdoor wood-fired boiler could have on your neighbors and their property
If you do purchase a unit, never use it to burn anything other than dry firewood, and to the extent you can, operate it only during the cold weather months.
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Burning Efficiently & Cleanly
How you operate and maintain your wood-burning appliance determines its combustion efficiency and the amount of air pollution it produces. Here are some tips for reducing the health risks and environmental impacts of burning wood to heat your home:
- Use small pieces of split wood that have been dried and seasoned for at least six months; preferably for a year or longer.
- Fuel your fire evenly but not excessively, since larger smoldering fires pollute the air more than smaller hot fires do.
- Leave enough room in the firebox for air to circulate freely around the wood.
- Never burn garbage, trash, treated woods or other highly polluting materials.
- Have your wood-burning appliance and chimney or stovepipe inspected and cleaned on a regular basis.