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Why Do Catalytic Combustors Need To Be Replaced?

There are 5 main reasons that a wood stove combustor may need to be replaced

Thermal Shock
Occurs when refueling with wood containing excess moisture either on it or in it. This is most common with green or un-aged wood. Moist smoke is sent to the combustor when the by-pass is closed and the results are thermal shock and cracking of the substrate. A continual practice of this will cause the combustor to deteriorate.

The catalytic combustor has a six-year life expectancy when used according to the stove owner’s manual. Although, some combustors have operated with efficiency for as high as ten years, the combustor’s life is based on the stove operator, maintenance, fuels used, and the stove manufacturer’s design.

Also known as "abuse to the combustor". A few examples would be…dropping it, using abrasive tools for cleaning it, using high pressure air to blow the cell free of any fly-ash build-up, using cleaning solvents to clean it or perhaps beating on it to remove it from it’s holding device.

Direct Flame Impingement
Flames burning for long periods of time directly into the combustor with the by-pass or damper closed will cause this. Allowing this to happen will change the make up of the catalyst and reduce the efficiency as well.
Flame impingement on a continual basis will cause the substrate to break down. Some of the reasons flame impingement occurs are operating the stove with the firebox door ajar or the ash pan not closed tightly. Air leaking around the door can sometimes occur if proper maintenance in not conducted on the outer gaskets. Other reasons might be that the door gasket needs replaced or the air intakes are left wide open after the by-pass has been closed. Uncontrollable draw or fast draft can be controlled with use of a barometric damper.

This happens by burning materials other than seasoned dried wood. Foreign matter such as garbage, painted wood, large amounts of colored paper, cardboard, rubber, plastic, paneling with glue, oily products and so on will eventually reduce the efficiency of the catalyst.

See our Combustor FAQ Page for visual examples of different combustor conditions.