Outdoor Boiler Pollution
You may see outdoor wood boilers referred to as outdoor wood furnaces or outdoor wood stoves. They function mainly to heat water which in turn provides your home with heat and hot water. While some states regulate the air quality of outdoor boilers, the federal government does not. Because these stoves emit wood smoke, environmentalists and those who live near these furnaces are concerned about the effects of that smoke.
Lack of Regulation
In the US, the Environmental Protection Agency (EPA) and Department of Energy (DOE) constitute the two main federal agencies concerned with pollution issues. Although regulations were established for indoor wood burners some time ago, outdoor boiler efficiencies still remain unregulated. The EPA has concluded that outdoor boilers release much more smoke than indoor woodstoves, and that these emissions don't typically disperse as well as the smoke emitted from indoor woodstoves.
Although no outdoor boiler efficiency ratings exist so far, the EPA encourages buyers to look for the cleanest burning units available. They also advise them to install them correctly, keep them clean, and not place them too near any neighbors.
In the meantime the agencies continue to work on several issues concerning outdoor boiler efficiencies. Their agenda includes deciding whether to establish regulations or to remain in an advisory capacity. They are also working on setting a standard test to measure emissions. For now, owners may compare a unit's output to voluntary emission standards set by the EPA.