Friday, November 14, 2008

A look at how the combustor works

Normally, smoke will burn, at a temperature of 1000 F. or higher. Burning a stove this hot would require continuous intense fire and would require a higher wood consumption.

The answer to eliminate this is the catalytic combustor.

Wood smoke gases coming in contact with the catalyst, causes chemical changes to take place. This will then allow the smoke to ignite at temperatures around 500 F. or (260 C.)

This temperature is easily achieved in the firebox of a wood burning stove.

As the wood gases ignite and burn within the catalytic combustor, clean by-products of water vapor (H2O) and carbon dioxide (CO2) are emitted.


dan said...

I just installed a Franks Piping indoor wood boiler in my basement it is an older unit perhaps from the 70’s (not wood gasification) but in good shape and best of all it was free. The unit very heavy about 1200 lbs empty and appears to be a combination of cast iron and boiler plate steel. It is tied into my oil fired boiler I am keeping the system at 180 degrees boiler temp (5 zones). My stack temp runs from 400 to 550 when calling for heat initially than drops to 200 to 350 range. When no zone is calling for heat and the boiler is maintaining stack temp drops around 100. I am using primarily Maple hardwood that was cut, split and stacked in the spring. I have a 7” diameter metal pipe upon exiting the stove it rises about 1’ than turns into one 90 degree elbow. It runs about 4’ before connecting into a 8” clay chimney (square) that runs through the center of my house and is about 20’ before it exits thought the roof. There is about 1’ of the flue that is above my roof line. I live in Northern Vermont in an old farm house (low grade insulation)
Do you need additional information?
My question to you is will I gain efficiency, less pollutants, less creosote buildup if I install a catalyst combustor in the 1’ of stove pipe before the elbow? Because the stove was not designed for a catalyst will I damage it?
Thank you

Tim Cork said...

Hi Dan,
Thanks for the questions.
I'm going to try and help you, but I cannot give advise on installing a catalytic combustor to a unit that was not designed for one.
Although, there are retrofit units available as add-on's to non-catalytic wood burning stoves, I would be affraid to try one with your set-up.
I would call Woodmans Parts Plus in East Wakefield, NH for advise on using these units.
1-800522-8216 or visit their website:

1. Catalytic combustors must be positioned corectlly in the units ehaust system for them to work and light-off.
2. They need a by-passed means while they are not up to temperature or for initial light-off.
3. Catalytic combustors need to be fed warm secondary air mixed with the firebox gases to make a proper ratio fuel for the combustor to work.
4. Catalytic combustors must be sized by volume and cell density to match the appliance flow rate.

So you see Dan, there's more to it than placing a catalytic combustor in the path of the smoke and gases.

I hope I've helped answer your questions.
Please visit my blogsite for more information on retrofits.