While building my own wood burning stove, I did some research on this topic. The EPA has rules for many aspects of the commercial and industrial industries. This is a set of rules, that like our vehicles affects the manufacturer of the product. Like our cars, it also affects the way we use the product.
Do the regulations the EPA (Environmental Protection Agency) sets, affect my wood burning stove? It does, as the standards set for wood burning stoves become stricter, manufacturers must meet those standards as they build new products.
As in any government agency, layers of standards, public opinion, and votes must be plodded through as regulations are debated and changed. The standards have been set and changed several times over the years, and a brief recap of that history and how wood stoves work is below.
History of Wood Burning Stoves
Before wood burning stoves became popular in the mid-1980’s, the typical location of
The first attempt to slow the flow of air up the chimney were glass doors that could be installed on the face of the fireplace. They helped slow the air up the chimney, but then little of the heat from the fire was radiated into the room.
The next step was a cast iron stove called a Franklin stove named after the inventor Ben Franklin. These were a step in the right direction but needed wood added about every 3-4 hours which was inconvenient at night and burned through a wood supply quickly (pun intended).
In the early 1980’s we realized that the flow of air into a stove could be controlled by making the firebox “air-tight”. This revolutionized the wood burning stove.
The first “air-tight” stoves had a welded steel firebox and doors that sealed almost air-tight. Air was introduced to the fire through an adjustable inlet, and we could now control the fire as desired. A real and efficient substitute for whole home heating was available.
The Government Gets Involved
When an industry starts to grow, of course, the US government has to stick
By 1998 those were re-visited, and the regulations were amplified. They were also further defined as to the method of testing. In 2015 the EPA stated that wood burning stoves would only allow an output of 4.5 Grams per hour of PM. This standard will be reduced again in 2020 to 2.0 Grams per hour of PM.
This standard output of PM may change as the Trump administration attempts to
Of course the battle between republican (small government, less regulation) and democrat (big government, more regulation) will not end any time soon. The ebb and flow of government will continue to affect the wood burning industry and those of us that burn wood.
What is PM?
With government meddling or helping (depending on your point of view), we should understand what they use as the standard of measure. All wood burning stoves manufactured for use in the United States must be independently tested and certified. The current standards stoves must meet is based on how much PM is exhausted (out the chimney) from a wood burner.
PM stands for Particulate Matter. PM is the chemical reaction of large and small particles in smoke caused by the burning wood. These are then carried out of the chimney in smoke. These particles are now required to be reduced by re-burning them inside of the stove. Currently, there are two systems designed to re-burn the PM inside of wood burning stoves.
In stoves that do not re-burn the PM, the particles either escape into the air or collect in the chimney.
The Two Types of Stoves
Since these regulations have been in force, two types of wood burning stoves have been developed to meet the EPA regulations. Catalytic and Non-Catalytic. A catalytic stove uses a catalytic device, similar to a catalytic converter in our vehicles, to re-burn the PM before it is sent to the chimney and then released into the atmosphere.
A non-catalytic stove does not use a catalytic device but instead, introduces pre-heated air for combustion over a baffle. The smoke then re-burns over the baffle, and the PM
How Stoves Work
Efficiency in wood burning stoves was dramatically increased by decreasing and controlling the air flow into a stove. By doing this, the PM output of a stove was increased.
This is obvious in the fall and spring when the outdoor temperatures are warmer, and we shut our vents down on our stoves. We do this to keep the temperature of our fire lower as we don’t require as much heat. The result is a buildup of creosote in the inside of our wood stove and chimney.
Do Catalytic Converters Affect Efficiency?
Typically a catalytic stove is as efficient as a non-catalytic depending on design. Both have to re-burn the PM in the smoke, and both have to meet the same standards set by the EPA. The advantage is there is less heat exiting the home and going up the chimney.
To achieve the burn off of the PM, the stove does have to reach a minimum temperature (typically 400 degrees F). On the other hand, more heat is gained from the stove by burning off the PM in the re-burn process.
There is an extra step involved in the startup process of the catalytic stove. A by-pass damper must be opened when lighting or bringing the stove up to temperature. That damper must then be closed to send the smoke through the catalytic device once the stove reaches the correct temperature.
The advantage is a hotter temperature burn for a longer period of time. The disadvantage is you have to keep watch of the stove and know when to close the bypass damper. A new temperature sensor made just for wood burning stoves can make this process easier and more convenient.
What about My Existing Stove?
So if you are wondering if the EPA is driving around looking for old wood burning stoves and taking them out of homes, that is not happening. First, there is no test available to check for PM in the air. The output of a stove is only able to be reliably checked in a lab situation.
Second, the regulations only apply to manufacturers, not the end users.
Third, the regulations state clearly that existing stoves are exempt from the new standards. Only new stoves manufactured by registered stove manufacturers are affected by the regulations.
Additional Questions
So after looking at regulations on stoves, the question may come up, “Are wood burning stoves more efficient than a natural gas furnace?” That is an excellent question that will take more than a few lines to answer. The answer depends on multiple variables such as; the cost of gas in your area, the availability of wood, and the cost of that wood. Typically, on average, wood stove heat will cost slightly more than natural gas heat.
It is certainly less work to turn the thermostat up a degree or two on a cold day. The alternative is to cut, split, stack, haul, and fire the wood, and then clean out the wood stove when done. I love the exercise but, some days (if I had gas in my area and a 98% efficient gas furnace) the gas furnace would get even my vote!
Are wood burning stoves more efficient than liquid propane heat? With all the variables calculated, this almost always comes up on the side of wood stove heat being less expensive. Unless you have someone on the inside supplying your LP gas or (Liquid Propane), even purchasing cut, split, and delivered wood is less expensive than propane heat.
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