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PostPosted: January 11th, 2004, 6:51 pm 
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Does anyone use the "backdraft method" mentioned by Calvin Rutstrom as the only proper way to control an all night fire in a woodstove?


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PostPosted: January 12th, 2004, 11:30 am 
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Not me. I've never understood it.


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PostPosted: January 12th, 2004, 11:44 am 
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any tentative explanation ? :o

will be very interest of not waking up to feed the monster with wood ....


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PostPosted: January 12th, 2004, 12:03 pm 
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Yes, the backdraft method.

The stove-pipe has two dampers (metal saucers which can be adjusted to regulate outgoing smoke) for this setup, one halfway between the stove and the tent ring, and the other covering an opening in the side of the stove pipe "proper" It is located between this damper and the stove, right above the stove, opening to the back.. It requires something similar to a "T" connector, the second damper sealing off the open section in the pipe.

What you now have is two sources of air for the draft to use, the adjustable stove draft, and the adjustable T connector in which air directl enters the pipe without fueling the fire or being warmed.

I do not understand how this works either. I hypothesize that the function of the opening in the pipe is to lessen the draft in the stove, but still allow plenty of O2 to enter. When you shut off the draft completely the fire may starve of oxygen and go out, but if you open the draft it gets too hot for an all-night fire. So by opening the pipe above the stove air enters and lessens the vacuum inside the stove, allowing you to operate the stove "draft open" for complete combustion, but not forced combustion.

What's to stop smoke from pouring out into the tent I wonder?


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PostPosted: January 12th, 2004, 12:33 pm 
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I think you might be refering to downdraft as opposed to the back draft. Which, if you think about it, it sounds like the same thing but its not.
Some of the commercial wood stoves refer to as having downdraft where the exhausted gases are redirected back through the fire where there is secondary combustion of the gases. This is usually done through internal ducts or baffles in the stove. I think its a good idea however, as this usually entails more material in the construction of the stove, weight all of a sudden becomes an issue. I also believe that this feature is only available in air-tight units. Most of the stoves we use in hot tenting are designed and manufactured to be light weight and are not that efficient, hence, they need to be fed every couple of hours. My stove last year did not have a chimney damper and I'm not sure if any of the units had them. Dave, please correct me if I am wrong.
Dan


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PostPosted: January 12th, 2004, 1:43 pm 
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what about these artificial logs?
Anyone tried one?


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PostPosted: January 12th, 2004, 3:20 pm 
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I can't see much of a difference between a damper and backdraft
method either. The damper reduces the draft by increasing the friction
in the stove pipe, while the backdraft method reduces the draft
by reducing the temperature in the stove pipe. Both should have
an identical effect of reducing the airflow through the stove box...

Speculating, perhaps the backdraft method modulates the draft
better as the fire burns down overnight. In other words, there may
be proportionally more draft reduction when the fire is burning
hotter at the beginning of the evening. Towards morning as the fire
has burned down, draft and temperature are lower, the effect
of the backdraft is comparatively lower, thus less draft reduction.
Meanwhile, the damper provides a fixed reduction to draft all night
long. I'd have to think it through a bit more, just a guess for now.


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PostPosted: January 12th, 2004, 3:37 pm 
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I am familiar with the draft arrangement used to improve combustion. I have a Pacific Stove woodstove, airtight with down draft in my house. Just love it BTW.

However what I am talking about is different. It's on page 72-73 of Calvin Rutstrum's "The New Way of the Wilderness".

He says that the basic unit uses a three inch pipe then he says that you should pass the pipe out through the side of the tent and now I quote -

A small T pipe at the end of the stack eliminates snow clogging. A second T on the pipe near the stove forms the back-draft and is the real secret to keeping an all-night wood fire going without having it run wild or go out. A cap made from a can, and placed over the the back-draft opening when starting a fire, allows the draft to draw through the normal channel. At night the cap is removed and the draft comes through the T. There is also a regular damper.
end quote

Perhaps my mentioning "complete combustion" was confusing. When my home stove is operating efficiently there is no smoke to be seen coming out the chimney. I'm pretty sure that the method I mention here will always produce smoke, and thus not be completely combusting.

I think the key is as emphasised in the above quote. Kinda like I explained in an earlier post. By allowing air to enter the pipe the draw is reduced and so you can open the draft full without it burning the place down. I think the "back-draft" allows for more control.

At any rate, the "T" piece required costs $5 so I'm going to experiment.


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PostPosted: March 22nd, 2021, 2:02 pm 
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Hello, has anyone ever figured out a solution to this problem??
I too am reading Calvin Rutstrums “paradise below zero”
And am amazed and frustrated at all the basic things that make winter camping better but are completely absent from modern equipment.

The back draft is a big one, the other being two layers of tent fabric to create a dead air space in between. Has anyone actually tried these methods out on the trail? Or found a retailer who supplies this kind of set-up?
I’d be happy to make the backdraft on my stove myself just not sure exactly out it would look.


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PostPosted: March 22nd, 2021, 7:22 pm 
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Sounds dangerous in a small heating system that is located in a area that is susceptible to rapid cooling.
Meaning that the stove and pipe will perform one way while the area is warm and will perform slightly different when the majority of the heat is gone.

So the benefit of this extra setup is how much longer? Still not through the night. So again, it doesn't seem worth it.

Where the pipe is located in your dwelling would have a great effect as well. Just like on your house.

Our tipi, for example, has better draft because the chimney exits at the highest point of the tipi.
Not as convenient for space as having the pipe on the side but better performance.

As far as the double walls... our Seekoutside tipi has a liner which creates a double wall to keep it warmer and help control condensation.


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PostPosted: March 22nd, 2021, 7:52 pm 
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Well I hadn't seen the actual quote there. The backdraft thing would serve an analagous function as the damper, but without requiring a constriction. The draw through the back tee will cool the flue gas and reduce draft, in direct proportion to the draft. So, like the damper, it will be a variable modulation over the course of a night's burn. Unlike the damper though it does not introduce a constriction. You can think of a constriction as being equivalent to a slightly reduced diameter with no constriction. So the backdraft method continues to operate with a 3" pipe, while the damper effectively reduces the pipe diameter to say 2.7", and otherwise they both do the same thing to modulate a long burn.


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PostPosted: March 23rd, 2021, 2:25 am 
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Well colour me purple, I love telling this story. Back in my college days (oh, about 15 years ago), I lived in Peterborough ON with an oil furnace, with a bunch of other students. Being students, we didn't always have money to refill the oil tank. But I was lucky enough to always have wood to burn, one of us was a competitive timbersport man, and we had a woodstove in the basement, hooked up to the HVAC.

Oh, you had to draft that thing properly, or campfire smoke would come out of every floor vent in the house and you'd be doing laundry for a week. It took us a while to figure out how to really use a woodstove effectively, but we did. The thing was, we essentially had to load it with hardwood and then suffocate it just enough that it would sort of flash over if the door was opened. I remember quite vividly one time, still figuring it all out, I opened the door just after it went out. I cracked the door open and it just... blew open. The flames jumped six feet from the stove. I was lucky.

It was really a matter of making sure that we put hard, heavy wood in there, and then choking it off just enough to keep it burning all night so we could just chuck more wood in, in the morning; enough to let it burn down to coals in the morning but still hot enough to heat the house, and yet still cold enough to not flash over when we opened it in the morning. Our goal was to shovel it every five days. But it was dangerous. Don't forget, this was in my college days, and friends would come over, we'd have parties, and inevitably, somebody would want to play with the damned woodstove. Quite a few people got quite scared by flashovers, and we had quite a few cold nights because somebody f|_|cked up the fire.

If there's one thing I've learned about all night fires in woodstoves, it's that it takes some experience, and no small modicum of mistakes and frustrations, cold nights, and near misses.

_________________
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PostPosted: March 23rd, 2021, 5:57 am 
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I'm not sure I'm understanding that "T" thing, but if I am, is it saying that you have section of pipe in the tent that is open? Not sure I would be down with that particular type of experimentation.

If you want to run a stove all night in a tent, and you are using a typical small type tent stove, you will just have to accept the fact that you are going to have to get up every hour or two to feed it.

Tents with liners, or insulated tents, do stay warmer, but we are talking about a very low "R" value difference. For instance, my insulated Eskimo 650 ice fishing pop up is much easier to heat than my snowtrekker. However, when the stove goes out, at cold temperatures, the 650 might stay marginally warmer for 15 minutes or so. The main difference is that I need less wood to keep it warm when I am burning.

Let us know how your experiment goes, some pictures would be great to see what you are doing. I have Rutstrom's book, buried in a box somewhere. Does he show any diagrams?


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