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Wood Stoves & Fireplaces: What does "EPA Exempt" mean?
Q: I am looking at high-efficiency zero-clearance wood stoves and have run across one (Napoleon NZ6000) that, rather than claiming to be
EPA-phase II approved, states that it is "EPA certification exempt."
What does this mean?
One dealer told me it was because the product was manufactured in Canada, but I suspect this is wrong as another similar product (NZ26) in the
same line is EPA-approved.
Is it because the product is not a true wood stove?
Does the exemption imply that the efficiency does not meet EPA standards?
Thanks for any help you can provide. No one seems to know the straight answer, and I cannot find it online.
Sherwood
A: The Napoleon NZ6000 is not exempt from EPA regulations because it is made in Canada. All wood-burning products sold in the US are
subject to EPA regulations, regardless of where they're built. However, the EPA regulations do allow for exemptions (wood-burners not required to
meet today's strict particulate emissions standards).
Exempted products include wood furnaces and cookstoves, as well as non-airtight fireplaces and wood stoves. To qualify for the non-airtight
exemption, a fireplace or stove must meet the EPA's definition, which requires a constant air-fuel ratio inside the firebox of at least 35-1. To
maintain this ratio, the stove or fireplace must allow a virtual free flow of air into the firebox. This airflow carries up to 90% of the heat from the fire
up the flue, which is why exempted wood-burners tend to fall into the "just for looks" category.
So, if exempted stoves and fireplaces are just for looks, why does Napoleon seem to be presenting the NZ6000 as heater, producing up to 60,000
btu/hr? In a word, marketing. The NZ6000's 4.8 cu.ft. firebox holds nearly 100 lbs. of wood, and a raging hardwood fire of that size can produce a lot
of heat: enough to provide meaningful warmth into the room despite the tremendous heat loss out the flue caused by the non-airtight design. The
capability of providing up to 60,000 btu into the room from a 100 lb. load is actually not bad, for an exempted, non-airtight fireplace, but is a far cry
from efficient wood heating. To put this in perspective, the airtight, EPA Approved Bis Ultima fireplace's 2 cu.ft. firebox holds just 40 lbs. of fuel,
yet produces nearly the same heat as the NZ6000, up to 55,000 btu/hr (to read more, click here).
The NZ6000 does allow some control of the fire, inside the 35-1 air/fuel requirements. Napoleon's literature states that they were able to achieve a
14-hour burn, which might imply that the NZ6000 has an airtight firebox, but that is not the case. Burn time figures can be misleading: a
manufacturer can use a solid block of hardwood that completely fills the firebox for this test, and if any hot coals can be raked out of the ashes 14
hours later, the brochure can advertise a 14 hour burn. And you can bet that the advertised 60,000 btu maximum output was NOT achieved during
the burn time test: note the "regular refueling" Napoleon mentions in the fine print linked to their heat output claim.
The bottom line? If you're looking for a fireplace with a big view of the raging fire, and want to get at least some meaningful heat from your 100-lb
loads of wood, the NZ6000 is worth a look. If your goal is to heat your house with wood, an EPA approved stove or fireplace would save you much
fuelwood, and be much kinder to the environment.
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Q: Hi: thanks for the great information. I noticed in some of your articles about EPA regulations that all wood heaters sold have to have a certain
emission control. Here in Okla. you can still buy a cast iron wood heater that is approximately l8 in. wide 2' tall and 3' long and install it yourself. It
doesn't have a secondary burn system or catalytic converter in it. It seems the EPA regulations are a little ambiguous when these are still sold.
Can you comment on this?
Dale Liston Jr
A: Sure can. In a nutshell, laboratory testing has shown that an open wood fire produces reasonably low emissions, but when the air supply
is reduced to the level at which the air-fuel ratio is lower than 35 parts air to 1 part fuel, particulate emissions begin to multiply. The EPA
regulations were created to induce manufacturers of so-called "airtight" wood heaters (which allow the operator to control the rate of burn by
reducing the air supply below the 35-1 level), to incorporate secondary burn systems that clean up the increased emissions.
Open fireplaces, which provide free access to as much air as the fire needs in order to burn with fairly low emissions, are exempt from EPA
regulations. The EPA regs also allow exemptions for wood stove models that similarly maintain the critical air/fuel ratio of at least 35-1 throughout
the burn. EPA exempt woodstoves are legal to install in all states except Washington, Oregon and California.
One example of an EPA exempt wood stove is a model we'll call the VB, which happens to be about the size you describe. In order to achieve its
EPA exempt status, the VB must consume enough air to maintain the required 35-1 air/fuel ratio at all times. Unfortunately, that amount of airflow
through the firebox causes the VB to perform more like a fireplace than an airtight, consuming over 11 pounds of fuel per hour at its lowest draft
setting. Depending upon which species of wood you're burning, this equates to a fuel consumption rate of 2-3 cords per month! By comparison, we
heat our 1460 sq.ft. house with about 2-1/2 cords per year in our EPA approved airtight.
So, if EPA exempt wood stoves are that uncontrollable and inefficient, why are they still sold? In a word, price: the VB is cast in China, of
inexpensive, recycled metal. No money is spent on low-emissions engineering, secondary burn system components, or testing. Further savings are
created by foregoing reduced clearance shielding and testing (the VB has a standard clearance listing, and must be located a whopping 36" away
from rear and side walls). To the unwary consumer who is shopping for price alone, the VB looks like a bargain.
Finally, here's the comment you asked for: The EPA regulations are far from ambiguous: they specifically allow you to purchase an EPA exempt
wood stove in Oklahoma. But do you really want to?
To read the actual text of the wood stove emissions regulations on the EPA's website, click here.
To view the EPA's list of exempt wood-burners, click here.
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