EPA's Air Rules for New Residential Wood Heaters
Summary of Proposed Requirements
for New Wood-fired Hydronic Heaters and Forced-Air Furnaces
On Jan. 3, 2014, the U.S. Environmental Protection Agency (EPA) proposed updates to its air
emissions standards for residential wood heaters that would strengthen the requirements for
new woodstoves, along with establishing the first standards for several other types of wood
new heaters, including new hydronic heaters and forced air furnaces. The proposal would
phase in emission limits over a five-year period, beginning in 2015. The proposed standards
would apply only to new wood heaters and will not affect wood heaters already in use in homes
or currently for sale today.
PROPOSED REQUIREMENTS FOR HYDRONIC HEATERS
•	Hydronic heaters (also called wood heaters or wood boilers) are usually located outside the
buildings they heat, in small sheds with short smokestacks. These units typically burn wood
to heat liquid (water or a combination of water and antifreeze) that is circulated through
pipes to provide heat and hot water to homes. They also can be used to heat workshops,
barns and greenhouses. Hydronic heaters sometimes are located indoors, and sometimes
they use other biomass as fuel (such as corn or wood pellets).
•	Hydronic heaters currently are not subject to EPA rules. Use of these heaters has increased
in some areas of the country in recent years, leading to concerns about the health effects of
the smoke they produce. In 2007, EPA launched a voluntary program to encourage
manufacturers to make hydronic heaters cleaner.
•	Through the voluntary Hydronic Heater Program, some manufacturers have redesigned
their models, making units available to consumers that are 90 percent cleaner than
unqualified models. More than 40 hydronic heater models currently meet EPA's
qualification requirements under the voluntary program.
•	EPA is proposing to build on the voluntary program to ensure that all new wood-fired
hydronic heaters are cleaner in the future. EPA's proposed updates would limit the amount
of particle pollution, also known as particulate matter (PM), from newly manufactured
hydronic heaters and forced air furnaces. The proposed limits also are expected to reduce
emissions of other pollutants found in wood smoke.
•	Today's proposed rule would establish PM emissions limits for these heaters in two steps:

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o In Step 1, the PM emissions limit for all new hydronic heaters would be identical to the
current qualifying level for EPA's voluntary Hydronic Heater Program. More than 40
hydronic heater models already meet this limit,
o In Step 2, hydronic heaters would have to meet stronger emissions limits (see table
below).
Proposed Emissions Limits and Compliance Deadlines for Hydronic Heaters
Step
Proposed PM Limit
Compliance Date
Step 1
0.32 pounds per million Btu
heat output, with a cap of 7.5
grams per hour for individual
test runs
60 days after final rule is
published in the Federal
Register
Step 2
0.06 pounds per million Btu
heat output
5 years after the effective
date of the final rule.
•	EPA also is seeking comment on phasing in the limits in three steps over an eight-year
period. This approach would include an interim emissions limit of 0.15 pounds per million
Btu heat output three years after the rule is published in the Federal Register.
•	Under today's proposal, new wood-fired hydronic heaters sold in the United States would
be required to have a permanent label indicating they are EPA-certified to meet emission
limits in the proposed rule. This label will signal to consumers that the heater meets EPA
standards.
•	The proposed rule would not apply to hydronic heaters that are fueled solely by gas, oil or
coal.
Forced Air Furnaces
•	Forced air furnaces, like hydronic heaters, burn wood to heat homes. However, heat from
these furnaces, which typically are located indoors, is distributed using a blower. Forced air
furnaces are not currently covered by EPA regulations. Today's proposed rule would
establish PM emissions limits for new forced air furnaces in two steps over a five-year
period:
Proposed Emissions Limits and Compliance Deadlines for Forced Air Furnaces
Step
Proposed PM Emissions Limit
Compliance Date
Step 1
0.93 pounds per million Btu
heat output, with a cap of 18
60 days after final rule is
published in the Federal

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grams per hour for individual
test runs
Register.
Step 2
0.06 pounds per million Btu
heat output
5 years after effective date of
the final rule.
•	EPA also is seeking comment on phasing in the limits in three steps over an eight-year
period. This approach would include an interim emissions limit of 0.15 pounds per million
Btu heat output three years after the rule is published in the Federal Register (the same
interim limit as for hydronic heaters).
DETERMINING COMPLIANCE
•	Each hydronic heater model line subject to the proposed rules would be required to
demonstrate compliance through performance testing, similar to requirements of the
current wood stove regulations. Under this certification program, one representative
appliance is tested by an accredited laboratory to demonstrate compliance for an entire
model line, which could consist of hundreds or thousands of units over the life of the model
line. EPA is proposing this approach rather than requiring manufacturers to test every
heater to minimize testing costs to manufacturers, most of which are small businesses.
•	EPA also is proposing changes to the test method that would be used to demonstrate
compliance with the proposed emissions limits. The changes would improve the precision of
the results and more accurately reflect real world conditions. The agency is seeking
comment on which test methods would be most appropriate and what other test method
improvements should be considered.
•	To strengthen compliance assurance and consumer confidence, the proposed standards
would require testing and certification by internationally accredited laboratories and
certification bodies. EPA would also review the tests and make the results available to the
public on a website.
For additional information
•	For additional information about today's proposal, including instructions on submitting
comments, see http://go.usa.gov/Zp6B.

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