Woodstove Problem: Catalytic Combustor

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Author – Todd Woofenden

Although there are countless different models of wood stoves, there are relatively few basic types of stoves, and the mechanical problems they experience are similar.  Your first step in caring for your stove is to read your owner’s manual for specific information on your model of stove. If you don’t have a manual, look for a label on the back of your stove that identifies the manufacturer and model, (or snap a photo of it if you can’t find any label) and go to your local stove shop. You may be able to purchase a manual. 

Here we will discuss some of the basic categories of problems you might experience, and what to do about them. We will cover:

  • Damper malfunction
  • Broken/stuck/loose handles
  • Warped or broken parts
  • Cracked or broken glass
  • Worn or missing gaskets 
  • Malfunctioning catalytic combustors
  • Poor performance 

Malfunctioning Catalytic Combustors


If your stove has a catalytic combustor, it is critical that it be in good working condition, as the efficiency of the stove depends almost entirely on the cat. 


How can you tell if the cat’s working?


In general, If you have followed the instructions for lighting the stove, waited until it is up to the correct temperature, and engaged the cat, within a few minutes the stove should be burning steadily, with little or no visible smoke exiting the chimney. So go outside and check once in a while, to see how it is doing. 

Some stoves have a probe thermometer mounted adjacent to the catalytic combustor that indicates its temperature. Once you have engaged the catalytic combustor, the temperature should quickly rise, often to 1200 degrees or more, although depending on the fuel you are using and how soon you engage the catalytic element, it could be lower, perhaps around 700 degrees. Check your owner’s manual for the correct readings for your stove. 

If the thermometer stays close to where it was before you engaged the cat, you have a problem. Either you didn’t wait for the stove to reach the correct temperature for light-off to occur, or the cat isn’t working. 

If you don’t have a catalytic thermometer on your model and you want one, you can purchase one to retrofit to your stove. These are essentially a metal probe on a wire that connects to a temperature meter. Ask about it at your local stove shop. 

What do you do if the cat’s not working?


Catalytic combustors are designed to last for a long time, generally five or six years, and sometimes more. How long yours will last depends on how much you use the stove and what you burn. 

First, you need to take the cat out of the stove. How to remove the cat varies. In some stove models, you simply remove a metal panel in the inside rear of the stove. In other cases you have to work a little harder. Check your owner’s manual or ask at your local stove shop for specific instructions for your model. 

Once you have removed it, inspect it. If the cat’s peeling badly, falling apart, or otherwise obviously in bad physical shape, replace it. But if it seems to be in tact, try cleaning it, first. 


How do you clean the cat?


The procedure involves washing the combustor in a hot water bath, with minimal abrasion (you don’t want to scrub it, as you will remove the catalytic element from the surface of the combustor, ruining it). Check your owner’s manual for specific instructions. You will find that annual cleaning is generally recommended. 

If you have lost your manual, ask at your local stove shop for a guide to cleaning catalytic combustors. It is pretty much the same procedure for all stoves. 

~ Todd Woofenden

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