On February 3, 2015, EPA strengthened its clean air standards for residential wood heaters to make new wood boilers significantly cleaner and improve air quality in communities where people burn wood for heat. As of May 15, 2015, small wood boilers are regulated both in Maryland and nationwide. MDE is in the process of aligning Maryland's regulation (COMAR 26.11.09.11 - Control of Particulate Matter from Small Wood Boilers) with the new federal regulation. For more information, please refer to the following:
The following table lists small wood boilers that have been approved for sale and use in Maryland. As of April 1, 2010, the Department will no longer certify Phase 1 models (0.60 pounds of particulate matter per million Btu). Phase 1 units may not be offered for sale or installed in Maryland after this date. Phase 1 units installed before March 31, 2010 may continue to be operated in Maryland. Phase 2 models, which meet a minimum 0.32 pounds of particulate matter per million Btu, are available for sale and installation, and may be operated in Maryland.
Model Name& Number
Annual Average Emission Level (lbs/million BTU)
The U.S. Environmental Protection Agency (EPA) maintains a list of small wood boilers that meet Phase 1 and Phase 2 emission standards. MDE has contacted manufacturers of small wood boilers and requested supporting documentation in order to certify small wood boilers for use in Maryland that meet the applicable emission standards. Please contact manufacturers if a particular model of interest is not listed among Marylands list of approved small wood boilers.
On May 15, 2015, revised federal New Source Performance Standards (NSPS) for new residential hydronic heaters became effective. The following previously verified units are not deemed EPA-certified under the NSPS because they were tested with the provious hydronic heater test method - M28 OWHH. Under a sell-through provision in the NSPS, these units could be sold until December 31, 2015. They may no longer be sold in the United States.
For more information, please refer to the following:http://www.epa.gov/compliance/list-epa-certified-hydronic-heaters.
The following units are no longer certified for sale in Maryland. Anyone who has these units installed may continue to operate them.
Small wood boilers (under 350,000 Btu/hr) made available for sale and use in Maryland after April 1, 2010 must meet an emissions performance standard of 0.32 pounds of particulate matter per million Btu of heat output.
As of April 1, 2009 small wood boilers made available for sale and use in Maryland must include an affixed permanent label that includes:
Owners and operators of new and existing small wood boilers are required to use only clean wood, wood pellets made from clean wood, or heating oil as fuel. The use of garbage, tires, asphalt products, manure and animal carcasses as fuel is prohibited. Click here for a complete list of prohibited fuels.
The Department recommends the following best practices for all small wood boilers:
In addition to the State, local and county governments have the authority to enforce certain provisions of this regulation and address citizen nuisance complaints that arise from the operation of small wood boilers. Local and county governments also have the authority to implement additional rules or restrictions.
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