Where's the Beef?

[HumaneSocietySteve]

Hey Fellow Burners,

This may be a Newbie question but I'm a Newbie so here goes.

I have an old, antique, non-cat, smoke dragon, not to mention many other terms of endearment I've heard used to describe my Classic VC Defiant and similar stoves. If I understand correctly the antique technology used in this stove is referred to as "horizontal combustion mode". This permits the wood pile in the stove to burn from the bottom 3 or 4 inches next to the ember bed and allows the wood pile to cook as it slowly descends into the coals while producing gases to create the magical secondary burn. This seems like a fairly straight forward concept and although I can't seem to get my VC Defiant to fully jump into this mode as of yet, I'm still experimenting and adjusting, it seems to be the same technology used today in non-cat stoves.

My Newbie question is:

How has the contemporary non-cat stoves such as the Joutul, that I read about on line earlier, do a better job than the old smoke dragons? What is the specific technology upgrades in these contemporary non-cat stoves that makes them so much more efficient than the technology used in the 70's?

 

[webbie]

The first answer is - the "famed" Vermont Castings horizontal combustion....pretty much did not work in the field. It might work in very cold weather with strong chimneys and large homes, but in actual use in homes all over the country, it pretty much did not work. So even back in the "classic" stove days, many customer opted for simpler designs like the Jotuls, Uplands and other "updraft" designs.

You are probably about to find this out the semi-hard way. It takes a LOT of chimney pull to make the fire go down and around.

Simply speaking, the newer stoves have smaller - and therefore much hotter, fireboxes. The boxes are also designed to carefully inject air at just the right places to create clean combustion. You'll notice that being called "secondary" burn, but it really means just a good flame on the fire....burning the "gas" content of wood, which represents as much as 50% of the heat which is in the wood.

The result is more heat from less wood, a cleaner chimney and a cleaner environment.

This is not magic - clean combustion of most fuels requires a hot chamber and the injection of air at the right places. Back when the Defiant was made, stove makers could (and did) claim just about anything. Today they have to prove it by passing standards which assure almost no smoke output from the stove (which means cleaner burning).

 

[HumaneSocietySteve]

Hey Craig,

Thanks for the great answer. I'm starting to understand.

So your saying the Defiant has a HUGE firebox that takes a tall and well designed chimney with tons of draft to make this machine work as advertised?

This may be my problem. I have loaded up the firebox with 3 or 4 splits of wood on a HOT bed of coals and let that get to cooking for several minutes. Then I shift into horizontal burn and the stove seems to stall and slowly but surely loses heat output.

I lit a match and snuffed out the flame to produce smoke and held it near the secondary are intake and draft damper as the stove was in horizontal burn and both were really sucking in the air. So it doesn't add up why the system isn't working.

When I open it up to see what is going on the splits are looking like charcoal but I don't see much flame at all. When the air rushes in from the door being open the flame starts going again.

If I were to extend the chimney to create more draft would that create the optimum environment for the Defiant to come into it's own as far as secondary burn is concerned?

What are the ways to optimize the Defiant taking into account the short comings you describe?

 

[Sandor]

Also, examine the path of the secondary burn chamber and make sure there are no obstructions.

 

[webbie]

Yeah, that is what I am saying. Sort of like driving a tractor trailer in the city, you are not going to get good mileage.

So whereas current stoves are designed for short chimneys, that stove was designed for an extremely tall (or strong) chimney. Any normal chimney, especially a masonry one in a ranch house, it unlikely to make it work. A straight up 8" might.

Having suction to draw in a match is a whole different thing than having suction to make the whole thing work as advertised.

 

[swestall]

So if you decide to buy a new stove, make sure you buy one that has secondary burn tubes or baffle and not one that has a modified downdraft design. (that still doesn't work)

 

[Eric Johnson]

If I were to extend the chimney to create more draft would that create the optimum environment for the Defiant to come into it's own as far as secondary burn is concerned?

I'd seriously consider getting a newer stove before spending money on a chimney modification that may or may not work, and is unnecessary with a more contemporary stove, anyway. The best you can hope for is a smoke dragon that works. And there's no guarantee on that. Why not get a clean-burning stove that works instead?