Combustion Portal


Masonry Heaters. A masonry heater is a site-built or site-assembled solid-fueled heating device, consisting of a firebox, a large masonry mass, and a maze of heat exchange channels. It stores heat from rapidly-burning fires within its masonry structure, and slowly releases the heat into the home throughout the day. Masonry heaters currently do not require EPA certification. The Masonry Heater Association of North America can provide you with more information on masonry heaters and installers near your area.

Hydronic Heaters

Hydronic Heaters (also called outdoor wood heaters or outdoor wood boilers) are typically located outsidethe buildings they heat in small sheds with short smokestacks. Typically, they burn wood to heat liquid (water or water-antifreeze) that is piped to provide heat and hot water to occupied buildings such as homes, barns and greenhouses. However, hydronic heaters may also be located indoors and they may use other biomass as fuel (such as corn or wood pellets)

Hydronic heaters are one of several appliances covered by EPA's Burn Wise Program.

EPA's Hydronic Heaters Program

The voluntary EPA hydronic heaters program was first launched in 2007, providing criteria for units to be 70 percent cleaner than unqualified models. The goal of the program is to achieve emission reductions and protect public health sooner than a federal rule. Today the program has evolved to Phase 2, and EPA-qualified units will be up to 90 percent cleaner than older unqualified units. Under Phase 2, new models must emit no more than 0.32 pounds of particle pollution per million BTUs of heat output. The models must be tested by an EPA-accredited third-party laboratory to verify that they meet these levels. See below for further information:

When purchasing new products, consumers should look for the hydronic heater hang tag to be certain that the product is efficient. Efficient, cleaner burning stoves save you money because they use 1/3 less wood for producing the same amount of heat. Read more about energy efficiency, on EPA's Burn Wise website.

For more information, contact John Dupree, (202) 564-5950 or dupree.john@epa.gov.

State Initiatives and Laws

With the increasing use of hydronic heaters nationwide, there is growing concern about the health and environmental effects of wood smoke. The burning of wood is known to produce a complex mixture of particulate and gaseous emissions. It can be a local problem because wood smoke is typically emitted close to the ground and is highly dependent on wind characteristics to dilute or disperse it. In response to these issues, many northern U.S. states and some southern states have implemented strategies to reduce air pollution from outdoor boilers. These strategies range from publishing good practices to enacting regulations with emissions standards (e.g., WA). Also, some states provide incentives such as rebates on purchases of more efficient units. Click on the state initials below to find more information for your state for outdoor wood boilers.

AL

AK

AZ

AR

CA

CO

CT

DE

FL

GA

HI

ID

IL

IN

IA

KS

KY

LA

ME

MD

MA

MI

MS

MO

MN

MT

NE

NV

NH

NJ

NM

NY

NC

ND

OH

OK

OR

PA

RI

SC

SD

TN

TX

UT

VT

VA

WA

WV

WI

WY

To report errors or updates on the above tables, please email George Cushnie.

Local Ordinances

Numerous jurisdictions have established legal requirements to reduce wood smoke. For example, some communities have restrictions on installing wood-burning appliances in new construction (see examples). The most common and least restrictive action is to limit use at those times when air quality is threatened. The appropriate agency issues an alert, similar to the widespread Ozone Action Day alerts. For more information, contact your local city or county government.

More Resources

EPA's Burn Wise website. A partnership program of the U.S. Environmental Protection Agency that emphasizes the importance of burning the right wood, the right way, in the right wood-burning appliance.

Strategies for Reducing Residential Wood Smoke (2009). This document was written for state, local and tribal air pollution control officials to have a comprehensive list of strategies to help communities reduce wood smoke from residential heating. It provides education and outreach tools, information on regulatory approaches to reduce wood smoke, as well as voluntary programs to change out old, inefficient wood stoves and fireplaces.

EPA's Burn Wise FAQs. This page provides answers to questions EPA has received about wood-burning appliances and wood smoke.