Maryland's current rule that regulates small wood boilers (COMAR 26-11.09.11) is in the process of being repealed, as since 2015 there are new federal rules (40 CFR Part 60, Subpart QQQQ) regulating residential hydronic heaters. The repeal of COMAR 26.11.09.11 removes any redundancy or potential conflict with the federal regulation - this includes the certification requirement for manufacturers who wish to make their units available for sale and use in the State. Residential hydronic heaters made available for sale and use in Maryland are subject all requirements and standards under 40 CFR Part 60, Subpart QQQQ. For more information, please refer to the following:
This web page will be revised to reflect the new regulatory requirements after they are adopted.
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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