Can one ADD a combustor to a non-cat stove ?

If there is room you would have to make exhaust is sealed so it is forced through the cat, and the top may not be able to handle the intense temps that cats put off. There are new stoves coming out that are hybrids, with both systems, to my understanding.

Check out the Elm, a pre-EPA design shown here with both burn tube and catalytic retrofits:
http://www.youtube.com/watch?v=2JdCQCtJyQo

petyanca said:

Hi Everyone, I have a Lopi Endeavor non-cat stove. I was thinking if I could add a combustor to it, so it would still be effective if secondary combustion doesn't happen for some reason. Has anybody played with such an idea ? There probably is enough room for it in the upper part, and some combustors being sold are oblong and I probably could cut extra to make it fit.

Click to expand...

I think you'd have to want to have a "project", for it to be worthwhile. From what I've read, there are a number of factors involved. I have a vague recollection that cats need some secondary air, though less than a non-cat. Not sure about that. But cats are subject to erosion from flame impingement, which gave early cats a bad reputation for frequent replacement. So you'd want to make sure flame doesn't hit the cat, have a protective plate if necessary, etc.

If it were already laid out for it, that would be one thing, but otherwise you'd be prototyping your own stove. I'm not saying that's a bad thing, just that I don't think it's a simple as dropping one in.

Total WAG here.

branchburner said:

Check out the Elm, a pre-EPA design shown here with both burn tube and catalytic retrofits:
http://www.youtube.com/watch?v=2JdCQCtJyQo

Click to expand...

Excellent, thanks. Best burning video I've seen. I frickin' love the look of those Elm stoves.

I wonder how long they burn...

There used to be a product that was jsut like a key damper in the stove pipe but instead of a cast iron plate it was a catalyst. You would start the fire with the cat turned vertical and then flip the cat horizontal to engage the cat. You can add this to any flue.

Note in the new woodstock stove pics that there are a couple of cats boted into the flue. 6" round.

Highbeam said:

There used to be a product that was jsut like a key damper in the stove pipe but instead of a cast iron plate it was a catalyst.

Click to expand...

They still sell 'em, right here in NH:
http://www.woodmanspartsplus.com/48...ombusters/Catalytic-Add--On-Stove-Damper.html

petyanca said:

As a matter of fact what if I put cat in the round part of the flue? I saw round shape combustors, 6" diameter, should be direct fit .. There would be a couple of inches of steel past the cat before it enters the pipe. Combustor would heat and heat distributed through flue to the still plates of the stove. Anybody knows why it won't work ?

Click to expand...

I never tried one, but from what I've read about the catalytic flue inserts, it is difficult to maintain the required temperature to keep the cat active (lit off), at least on lower burn settings. It's much easier to maintain the required temperature inside the stove itself.

I understand that a properly designed cat stove needs: a source of combustion air near the combustor; a flame guard to shield against direct flame impingement of the combustor surface; flue gas turbulence prior to entering the cat (may also be accomplished by the flame guard screen); a positive shut-off bypass device; and some thermal mass near/around the combustor to maintain temperature. The Woodstock Classic has a piece of cast iron (I believe it's cast) around the combustor that holds it in place and also retains temperature around the combustor. Woodstock and Blaze King have their combustors arranged vertically (standing up) as opposed to horizontally (lying flat), so the flame won't rise and directly hit the combustor, the flue gas experiences a 180 degree turn prior to the flame guard and combustor.

I considered trying a cat retrofit on an old stove I had in the basement, but decided against it due to the amount of modification required to create an airtight bypass damper inside the stove and an operating mechanism on the outside of the stove. Also, I found that it would be difficult to get a correct location that was accessible for removal of the combustor. There was a story once in Mother Earth News about a cat retrofit inside a stove, I think you can find it if you search for it online. I did a secondary air retrofit instead, it was much easier. Search for "Bullard Retrofit" in this forum for a description and pictures.

Hope this helps!