Posts made in August 2012

How to Reduce your Chimney and Fireplace Pollution

Heating with Wood and the Environment – part 5: 7 Ways to Reduce your Chimney and Fireplace Pollution

Earlier on in our series, “Heating with Wood and the Environment”, we discussed the environmental issues of burning wood. We also discussed how what firewood you burn and how you operate a fire affect the environment. Last time, we compared the pollution rates of wood stoves and other wood burning appliances. In this article, we conclude the series by discussing why your fireplace and chimney may be polluting more than it should.



In general, the more efficiently you burn a fuel, like wood, the less smoke is produced per unit of energy. Since smoke contains the polluting gasses and fine particulate matter we want to reduce, it makes sense to ensure that your fireplace and chimney is setup to conserve heat and burn wood more efficiently. As a bonus, this also saves you money. In addition, an improperly functioning chimney may burn so inefficiently as to cause your firewood to not combust completely; poisonous gas like carbon monoxide is the possible consequence of incomplete combustion.

Since increasing the efficiency of your fireplace and chimney decreases pollution, there are actually a ton of ways you can reduce the pollution coming from your chimney. Below are 7.

1.     Ensure proper installation

Improper fireplace insert installation, chimney liner installation, factory chimney installation, masonry chimney construction, or venting configuration will decrease efficiency, increase fire hazard, and increase indoor and outdoor pollution. The number of things that can be done wrong is quite a lengthy list. For example, if the outlet on a fireplace insert is larger than the flue in your chimney, an airflow imbalance may result and the insert may not receive adequate air to combust at full efficiency. Similar chimney airflow problems might occur with other installation errors like improperly sized chimney liners or chimneys that are not tall enough. If you are getting any installations done, make sure you use an experienced, certified technician, and make sure they follow code, standards, and manufacturer’s instructions. Getting a thorough inspection of your chimney and fireplace by a qualified technician will ensure that installations have been done correctly.

2.     Make sure the damper is fully open during use

Many homeowners forget to open the damper to allow air to flow out of the chimney. It is also common for dampers to stop opening fully because buildup or damage; a partially open damper only allows partial airflow and may decrease fireplace efficiency.

3.     Don’t tolerate indoor smoke

In a properly functioning fireplace, smoke should only go in one direction: up. Indoor smoke is generally cause by the fact that air is being pulled away from the chimney and force of smoke’s naturally tendency to rise straight up through the chimney is not strong enough to pull air into the chimney to counteract the forces pulling air away from the chimney.  If you are getting house smoke, indoor pollution is your first concern — you do not want your family breathing in smoke. Your secondary concern is that the fireplace is likely not receiving enough incoming air (due to competing airflows) to burn efficiently, thus also increasing outdoor pollution. Always remember that indoor smoke is a fixable problem that must be solved.

4.     Get your chimney cleaned

The natural buildup of soot over time decreases chimney performance. According to the CSIA (Chimney Safety Institute of America), a ½ inch buildup will restrict air flow by 17% for a typical masonry chimney and 30% for the average prefabricate chimney. A clean chimney burns more efficiently.

5.     Have a good liner

A chimney liner has a number of benefits in pollution reduction. A properly sized liner can make up for a flue that is too big for your fireplace insert. A chimney liner also helps keep the air inside the flue hot, to keep air moving up along as it should. In addition, the liner helps keep the cold out; a chimney (especially external masonry chimneys in northern climates) can get rather cold and will make the air inside the flue colder, restricting airflow and efficiency. A good liner will also help things dry inside the flue and fireplace, to the benefit of efficiency. These benefits are all in addition to the benefit the liner has of decreasing fire hazard. Thus, it pays to have an undamaged, properly sized, solid performing liner.

6.     Cover up well

Make sure you have the right kind of cover on the top of your chimney keep out rain and pests out. Pests such as nesting birds can really block airflow. A flue that is wet inside will always produce more smoke. Masonry chimneys will probably need a crown and cap; factory chimneys will probably need a chase cover. Your chimney may alternatively use a top sealing damper. Make sure your chimney has a cover, particularly one that best makes sense for your situation.

7.     Get Inspected

We mentioned already that a chimney inspection by a qualified and certified technician will ensure you chimney and fireplace are installed as they should be. An annual inspection is also a very important way to ensure your chimney is being properly maintained. A poorly maintained chimney is an inefficient and overly-polluting chimney.

Environmental Comparison of Wood-Burning Stoves

Heating with Wood and the Environment – part 4: How Different Types of Wood Burning Appliances Affect the Environment


Earlier on in our series, “Heating with Wood and the Environment”, we discussed the pollutants and other environmental concerns in burning wood. We also discussed how what you burn and how you operate a fire can really reduce negative environmental impacts. In this article, we shall discuss how different types of wood burning appliances will affect your contribution to pollution rates.

Different types of wood burning appliances have different capabilities when it comes to how efficiently they maintain a flame and how complete the combustion is. Higher efficiency appliances require less wood is to provide heat and therefore produce less pollution, such as fine particulate matter. The main classes of indoor wood-burning appliances are listed below:

  • Wood pellet stoves are generally the most environmentally friendly and efficient wood-burning appliance. Wood pellet stoves burns small pellets derived from dried wood and other biomass waste. The wood pellets are fed into the main burn area via a small electrical device.
  • EPA-certified Wood stoves or fireplace inserts represent the next most efficient class. A wood stove generally consists of a solid metal closed fire chamber and has adjustable air control. A wood burning fireplace insert is basically a wood stove inserted into the fireplace, as opposed to a freestanding wood stove.
  • Masonry Heaters are appliances which retain heat through a large masonry mass and a maze of heat exchange channels.
  • Basic chimney and fireplace

However, note that the specific design and construction of an appliance has just has much impact on efficiency as the type of appliance.

The efficiency of wood stoves and inserts varies tremendously from model to model. One factor is whether or not the wood stove uses a catalytic converter; catalytic woodstoves are typically less polluting. Also, the difference in pollution between an EPA-certified woodstove and a non-EPA stove is tremendous. Even among EPA certified models, there are very large differences.  The environmental-friendliness of a wood stove is usually measured by two metrics: GMs/hr, or grams of particulate matter emitted per hour, and efficiency rating. For example the Regency Classic™ F1100 Wood Stove has a GMs/hr of 3.0 and is 77.7% efficient at optimal operation.

Thinking about replacing an old wood stove or fireplace insert? There may be government incentives for upgrading to a more environmentally friendly device. Be sure to check if your state has a changeout program or other incentive programs. Maryland for example, just started offering rebates for wood and pellet stoves.

Fireplaces also have a huge variety in efficiency. Typically, a factory-built fireplace, also known as a “low mass fireplace” will be more efficient. However, it is not uncommon for a family’s masonry fireplace to be more efficient than a neighbor’s prefabricated fireplace. Again, the design and construction plays a huge role in efficiency. The quality of the installation and the situation of the chimney also are important.

Learn what you can do to your chimney and fireplace to reduce pollution in part 5 of the Heating with Wood and the Environment series.