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  #91  
Old 11-26-2007, 01:20 AM
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Join Date: Nov 2007
Location: Washington Maine
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Default Re: Starting your fire

It does not matter weather or not the wood is green or air dried, I am simply saying, in my somewhat experienced opinion, that trying to get a jump on the next fireing by "drying" the wood in a hot, recently fired and baked in bread
oven is not only a false economy, but can be dangerous, and that saturating the interior of an oven, and chimney with creosote from charring firewood, that is also absorbed by the firebrick, does no good.

I have no idea of the circumstances of that poster that dries wood in their oven, they did not say.
I am not saying that a top down burn reduces outgassing. We want outgassing since that IS how wood burns.
Much of the gasses from wood combustion do not burn properly in a oven/firebox that is not hot enough yet
I am theorizing that the wood outgasses will ignite much more fully when the wood is well heated somewhat gradually, as opposed to wood just loaded (at a core temp somewhere between room temp and whatever the temp is of the wood that is just brought in from outside) and subjected to a rush of flame from paper and kindling.
Anyway, the proof is in the pudding. It works for me, I feel good about it, and most of the other members of our Masonry Heater Assn agree and teach it to their clients.
But don't just take my word for it, try it and see for yourself. You can always go back to your own favorite method.
The customer I spoke of in my post is a commercial breadbaker, and has a burn in his oven every day, and very often would dry wood more fully regardless of if the wood is green or air dried.
They do not bake their firewood in the bread oven any longer, just their bread.
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  #92  
Old 11-26-2007, 05:56 AM
oventhusiast's Avatar
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Join Date: Mar 2005
Location: Boston (area), Ma. USA
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Default Re: Starting your fire

Hey JP!,
I'm going to try the stacking method you explained. It makes much sense to me. I've been using newspaper because that's the only thing that's available to me. Not much around here in the way of dried twigs. (I'll need to hunt them down.) And you are absolutely right about the newspaper, etc., blackening the dome interior with soot and creosote. That's the one thing I'm not too comfortable with as it coats the entire dome with a thick black, almosy greasy, soot and tends to smoke out the neighbors a bit upon start-up.
Thanks,
Rick
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  #93  
Old 11-26-2007, 08:41 AM
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Default Re: Starting your fire

I read an article about top down fires recently and thouight, what a lot of garbage, how on earth should that work? ...And now I read it again here. So maybe there's something in it after all

OK, I'll try it, the next time I light a fire...
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  #94  
Old 11-26-2007, 09:49 AM
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Default Re: Starting your fire

I've been using my homemade propane-powered venturi burner.

It works quit nicely for a little preheating too!

I'm gonna start a thread on it soon.

Just have to make it through the busy holidays.
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  #95  
Old 11-28-2007, 02:56 AM
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Default Re: Starting your fire

This snip of this post below from the stovers list recently touched on a more scientific explanation of what we call a top down burn. It is being used here in a different application below that focuses attention on developing small efficient cooking and heating stoves for families in developing countries, but the process is the same.

The criteria for air coming "up under the bottom" is provided in an oven or masonry heater by the first course of wood on the bottom being laid front to back, providing a channel for air coming into the oven thru the door to reach the core and rear of the wood stack pretty much equally.




Dear All:

If you have a vessel full of biomass and air coming in the bottom (under
a grate, maybe) and light it on top you have a Toplit Updraft (inverted
downdraft) gasifier and the temperature rises from room to ~600C as the
flame front (flaming pyrolysis) passes down, leaving 15-25% charcoal in
its wake and making a very combustible gas.

If you then allow the flame to finish in the TLUD mode, you can fill the
vessel a second time with more biomass and continue in the conventional
BLUD (Bottom Lit Updraft) mode, the same that is used in Lurgi gasifiers
with coal. The hot gases from the charcoal begin drying the fuel and
the gas won't support combustion until _all_ the water has been removed
(white smoke, non combustible). Then there is a long period when the
pyrolysis gas is combustible and eventually becomes all charcoal. But
the pyrolysis takes much longer and gives a different type of gas then
the TLUD operation. Both have their unique advantages.

TOM REED BEF

Da

<stoves@listserv.repp.org>
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  #96  
Old 11-28-2007, 12:49 PM
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Location: Pebble Beach, CA
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Default Re: Starting your fire

Hey JP,

Welcome aboard. It's great having such an experienced builder in the community -- thanks for sharing your knowledge. I keep meaning for FB to join the masonry heater association -- and we need to do that. If my memory is right (which if highly questionable), you answered questions for me by email quite a few years ago when I built my first Scott oven. A renewed thanks for that.

I look forward to trying the top down burn.

James
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  #97  
Old 11-29-2007, 03:47 AM
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Location: Washington Maine
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Default Re: Starting your fire

Hi James
You, or anyone that is really interested in learning and sharing knowledge regarding bakeoven construction, design, operation etc should be a member the Masonry Heater Assn.
Besides all the emissions testing procedures we have developed and are currently developing, and have performed on dozens of masonry heaters establishing a substancial base line of emissions data, developing a masonry heater education and certification program, the writing of the ASTM standard that is referanced in our national code, and many other projects and programs, its our annual meeting in the mountains of North carolina that get top rating.
Its a week of a variety of masonry heater and bakeoven discussion and construction, then firing and testing whatever varities of heaters and bakeovens that we do in any given year.
We have members from the US, Canada, Sweden, Germany, Japan, Finland and probably a few more that I dont recall off hand. And many join us at Wildacres. It makes qiute a mix!
Various presentations from our members every evening in our hall, excellent food, spectacular views, hands on bricks and mud sessions.
A MHA member, or guest oven builder, leads a bakeoven build over the week, then it is used to make lots of pizza for our annual pizza party.
The morning after we all break down the builds and stash the bricks away in the barn for next year and head home.
Check out the photo reports on various years at the MHS e-zine at.. Masonry Heater Association News - The Heater Mason's E-Zine
Scroll down the page for a link and try to stay focused or you will get sidetracked on another interesting link along the way down.

I suppose at this point I should add that I am a founding member of the MHA, and I served on its executive for 6 years in the late 90's, and I take most any opportunity to promote our efforts.

Anyway James, I hope to see you there this spring.

JP







Quote:
Originally Posted by james View Post
Hey JP,

Welcome aboard. It's great having such an experienced builder in the community -- thanks for sharing your knowledge. I keep meaning for FB to join the masonry heater association -- and we need to do that. If my memory is right (which if highly questionable), you answered questions for me by email quite a few years ago when I built my first Scott oven. A renewed thanks for that.

I look forward to trying the top down burn.

James
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  #98  
Old 11-29-2007, 06:53 AM
PizzaPolice's Avatar
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Default Re: Starting your fire

You can say that again!
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  #99  
Old 11-29-2007, 09:05 AM
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Join Date: Jul 2007
Location: Ohio
Posts: 101
Default Re: Starting your fire

Flint rocks and tender on calm days, gasoline and a torch on the windy days... just kidding.
If I can't get a fire going with a match, newspaper, and kindling then I should have never left my electric range.
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  #100  
Old 11-29-2007, 09:08 AM
Il Pizzaiolo
 
Join Date: Jan 2007
Location: Tampa, FL
Posts: 1,446
Default Re: Starting your fire

If I can't get a fire going with a match, newspaper, and kindling then I should have never left my electric range.[/QUOTE]

I will second that

RT
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