East Amwell Board of Health Advisory

OUTDOOR WOOD BURNERS - DID YOU KNOW…?

Thinking about purchasing an outdoor wood-fired boiler (OWB) for your heating needs? These are units that have become popular recently in the northern quarter of the country based on claims of high efficiency, low cost and the appeal of replacing of fossil fuels with wood. The units are self contained, shed-like structures that consist of a firebox and a water jacket. The wood fire heats water that is pumped to the house where it is used to heat the housing spaces as well as domestic water. While replacement of fuel oil or natural gas furnaces with a heating system based on a renewable resource may seem like a good idea, a recent study by the Northeast States for Coordinated Air Use Management (NESCAUM, www.nescaum.org) issued an extensive assessment of wood-fired boilers in March 2006.

Consider the following:

OWBs typically do not contain pollution control devices found on indoor wood stoves. As a result, they emit significantly more particulate matter than other heating equipment:

1 OWB = 22 EPA certified indoor wood stoves

1 OWB = 205 oil furnaces

1 OWB = 8000 natural gas furnaces

Another comparison to keep in mind is that one OWB emits as much fine particulate matter as four heavy diesel trucks on a gram per hour basis.

Due to the door dampers used to regulate heating cycles, short-term pollution spikes, resulting from dense smoke, can be extremely high.
Most OWB kits have chimneys with heights of twelve feet or less. As a result, the dense smoke is emitted very close to the ground where it cannot be properly dispersed, therefore exposing residents to the pollution. Buildings within a 150-foot radius of an OWB can experience high levels of pollution during typical operation. Children, the elderly, and those with asthma or other respiratory illnesses can potentially be severely affected by such exposure.
While the amount of particulates is known to be high as indicated above, information related to emissions of toxic chemicals resulting from incomplete combustion is not known.

Manufacturers’ efficiency claims of up to 95% were not confirmed in NESCAUM’s study, which showed efficiencies ranging from 28-55%. An EPA study quoted in the report indicated typical efficiencies of 30-40%. This is most likely due to the use pattern, advertised as an advantage by manufacturers, of filling the fire-box with wood which, combined with minimal tending, results in a smoldering, inefficient fire over long periods of time. Use of green or scrap wood only makes the situation worse.

While several New England and Mid-Atlantic states have petitioned the federal government to provide regulations on OWBs, none have been issued to date. As a result, states and municipalities are considering local ordinances to deal with the air pollution issue created by OWBs. East Amwell Township does not have specific regulations about the use of OWBs currently. But, installation of such a unit requires a building permit that can be obtained from the township construction official.