Cycles of firing

Don't expect perfectly steady heat output from the fire. Wood fires burn best in cycles. A cycle is the time between the ignition of a load from charcoal and the consumption of the load back to a coal bed.

Each cycle should provide between four and eight hours of heating, depending on how much wood was used and how much heat is needed.

Plan the firing cycles around your household routine. If someone is home to tend the fire, use a short firing cycle. If you must be away from the house during the day, use the extended firing cycle.

What makes a woodstove clean burning?

Wood smoke is unburned fuel, some of which accumulates in your chimney as creosote while the remainder exits the stack as smoke. The key to reducing air pollution from woodstoves is to burn fuel more completely.
Three things make a stove clean burning:
a. How it is designed.
b. How it is installed.
c. How it is operated.

Some stove manufacturers use catalytic combustors to burn fuel more completely while others use a variety of design features such as baffles, secondary combustion chambers, and introduction of secondary air.



EPA-certified stoves offer 70 to 90 percent reduction of particulate matter over the older conventional model stoves. This is based on laboratory testing.

How to achieve catalytic combustor light-off and maintain catalytic burning conditions.

How to achieve catalytic combustor light-off and maintain catalytic burning conditions
When initially starting a cold stove, a medium to high firing rate must be maintained for 20 to 30 minutes. This will allow the stove, the catalytic combustor and the fuel to stabilize at a proper operating temperature.

Even though temperature can reach 600 F. within a few minutes after the fire has started, if the fire is turned down too soon to a low burning condition, it will result in the fire and/or the catalytic combustor going out.

At the end of a burn cycle, it’s possible that the amount of burning charcoal remaining might not provide sufficient temperature or fuel for the catalyst to stay lit.

During the refueling of a hot stove that has an internal temperature below 500 F., it is best to fire the stove up for 10 to 15 minutes to ensure sufficient temperature and proper amounts of volatile gases for the catalyst to operate well and efficiently.

However, when refueling a hot stove that has an internal temperature above 500 F., no re-firing is necessary.

What are the best operating temperatures for the combustor?

Combustor temperatures can become extremely hot during operation.


And temperatures above 1800 degrees F. will damage the catalyst.


Temperatures between 1400 to 1600 degrees F. are normal, but temperatures between 1200 degrees F to 1400 degrees F. are recommended.

What causes thermal shock to the combustor?

A sudden temperature change or uneven temperatures to the combustor's substrate can cause cracking. One of the main reasons for this happening is refueling with wood containing some form of moisture. This can be wood that has been exposed to snow or rain, or perhaps green wood that has not been stacked and seasoned for at least one year.
Thermal shock happens when the moist smoke comes in contact with the combustor running at temperatures in excess of 1000 dregrees F (540 degrees C). The cell walls will develope hairline cracks and eventually pieces will start to fall off the combustor. This loss of surface area means there will be less catalytic surface space and less efficiency of the combustor.

Getting the best life out of the catalytic combustor.

The catalyst was designed to burn seasoned dried wood only. Burning garbage, painted wood, products with glue, plastic, rubber, large amounts of colored paper, petroleum products and other foreign materials will poison your unit if done on a regular basis.

Eliminate all doubt on this subject by burning ONLY SEASON DRIED WOOD.

Understanding the catalytic combustor

This is the first of a series of articles on understanding the catalytic combustor a little better.

Why is flame impingement bad for the catalyst?

Direct flame contact is death to the catalyst. A catalyst burns the byproducts in the smoke. The gases such as CO, HC and O2 ignite with each other in a chemical reaction in the presence of the catalyst (while passing through the honeycomb configuration). Direct flame inhabits this reaction by changing the chemical make-up of the catalyst breaking down the substrate or ceramic. Today's modern wood burning stoves are designed so that flame impingement is unlikely. However, it is not impossible. A strong fast draft can pull the flames into the catalyst. A hot fire with all the primary air controls wide open or perhaps the firebox door or ash pan door ajar are other ways the catalyst might receive flame impingement.

Operating a Catalytic Woodburning Stove

All this month will be focused on understanding a catalytic stove and the catalytic combustor inside. Let's start with some basic information and tips that will help you to have a trouble-free burning season. More detailed information will follow with each posting I make throughout the month.

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