THE CATALYTIC COMBUSTOR
Here is how your catalytic combustor works.
The catalytic combustor is a stainless steel honeycomb with hundreds of cells. If you looked at the inside of each cell
with a microscope, you would see that the walls are uneven and filled with minute nooks and crannies. Precious metals,
such as platinum, are sprayed on the inside of these cells to coat all of the nooks and crannies. This creates the largest
possible surface area to interact with the wood smoke. The catalytic combustor in your stove is very similar to the one in
the exhaust system of your automobile and works to achieve the same results - high efficiency and clean air!
When you first start a fire, you should bypass your catalytic combustor and let the
smoke go directly up the chimney. Once wood smoke reaches 500º F (about 10-15 minutes
after restablishing a strong fire), it is hot enough to ignite the catalytic combustor. As the
wood smoke passes through the cells in the combustor, the smoke reacts with the precious
metals which line the inside of the honeycomb and both combustible gases and particles in
the smoke ignite and burn. This “catalytic burn” reduces emissions and also increases heat
output from the stove.
Without a catalytic combustor, between 5% - 40% of the chemical energy contained in
wood simply escapes up the chimney when wood is burned. Energy laden gases are
exhausted up the chimney where they pollute the air or may condense on the inside of the
chimney flue as creosote. The slower the burn, without a catalytic combustor, the greater
the amount of energy that is lost. A long smoldering fire is the least efficient use of energy
in wood, yet it produces lots of smoke, which is the fuel supply for the catalytic combustor.
Most of the chemical compounds in wood smoke are combustible. The catalyst produces high temperatures, which
loosen the bonds of these chemical compounds and “burns” wood smoke. A stove that “burns” these compounds and
uses smoke as additional fuel will burn more efficiently and produce more heat, while reducing creosote and air
pollution at the same time. However, most stoves cannot consistently produce temperatures high enough to burn
cleanly, particularly during long burning times - hence the need for a catalytic combustor.
Your catalytic combustor can get the most efficiency out of every piece of wood if it has three things: temperature,
turbulence, and time.
1. Temperature.
The catalytic combustor can only start burning the gases in the wood smoke after the smoke has reached
at least 500 degrees F. Before the smoke reaches that temperature, it simply is not hot enough to start the reaction at
the combustor. This will result in an inefficient smoldering fire.
2. Turbulence.
The wood smoke can interact best with the precious metals inside the honeycomb cells if there is some
variation in the air flow. Increased turbulence enables more of the wood smoke to come into contact with more of the
nooks and crannies in the honeycomb cells. The exhaust path as well as the irregular surface of the combuster cells
adds needed turbulence.
3. Time.
Once the temperature and turbulence are achieved, the catalytic combustor just needs to have enough time to
burn all the gases in the wood smoke. For this reason, it is best to minimize the amount of air you allow into the
firebox once the combustor is ignited. Allowing too much air into the firebox speeds up the rate at which the fire
burns and allows more wood smoke to be consumed by the secondary combustion system . The ideal air setting for a
long catalytic burn allows enough air to keep the wood burning and producing smoke.
With proper care, a new catalytic combustor will give years of fuel savings and lowered emissions. By following
some simple guidelines you can ensure maximum combustor performance and longevity. Your catalytic combustor is
designed to last for 12,000 -14,000 hours of use. You can ensure yourself of getting the maximum life from your
combustor by following these simple guidelines:
1)
Burn only natural, dry wood.
2)
Wait until the exhaust gases reach about 500 degrees F before engaging the catalytic combustor (about 5-15
minutes, or 250° on single wall stove pipe, after establishing a strong fire).
3)
Bypass the combustor before reloading, and leave the bypass open for a few minutes after reloading, to raise
the temperature in the stove.
4)
Don’t overfire the stove.
5)
Clean the combustor regularly. See instructions below.
You can also obtain a lot of useful information by visiting our website (
www.woodstove.com
). Other very useful web
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Simple radiator installed
above catalyst
