EFFICIENT BURNING OF WOOD (almost smokeless)

[v12spirit]

Found this article that explains how to burn your wood efficiently so that the majority of the potential thermal energy in wood is exploited, and the emitted smoke is minimum. About 50% wood saving is claimed. I read it is 30-50% in other articles. The author applies it on a fireplace. I think it should hold in a WFO:

How to Build an Upside-Down Fire: The Only Fireplace Method You'll Ever Need | The Blog of Author Tim Ferriss

Just included the offline saved file in case the link dies.

[stonecutter]

Re: EFFICIENT BURNING OF WOOD (almost smokeless)

Interesting article, but I don't see how that method would be useful in a wood oven at all, since the draw and exposure are completely different that fireplaces.

[cobblerdave]

Re: EFFICIENT BURNING OF WOOD (almost smokeless)

G'day
Starting a fire in a wood fired oven - YouTube

On the same theme this is a method for the wood fired oven of the same type of fire. I've tried it and have found you have to be careful its a case of not too much wood cause once it catches you can find the flames licking out the chimney, which of course is a waste of heat.
Regards dave

[david s]

Re: EFFICIENT BURNING OF WOOD (almost smokeless)

Using your oven to dry wood can have a safety issue if you place the wood in the oven and it's too hot. On opening the door the wood can spontaneously combust. Secondly if you get a raging fire going like the youtube video shows, then you are increasing the temperature way too fast (around 500C/hr) for the refractory to cope with. This can lead to damage and the continued practice is likely to shorten the life of the refractory.

[v12spirit]

Re: EFFICIENT BURNING OF WOOD (almost smokeless)

Maybe in the upside-down method, the saved consumed wood will be dissipated through the chimney, and the flames, being high, will not warm the hearth up.
IMO this method is best exploited in a WFO by laying one (up to 2) layer(s) of wood on the hearth and topping it with paper pieces and straws and giving them a match. This will abate start up smoke by the inherent property of the method and by the flames that warm up the chimney allowing it to better draw the smoke. Then the fire is left to burn the wood slowly and completely giving out more heat inside the chamber where convection and radiation can compensate for conduction.
The wood layer(s), being under half the door height, will be guaranteed proper draw, not far different than in a fireplace so long as cold air enters from the lower half of the door and hot air exits from the upper half.

[cobblerdave]

Re: EFFICIENT BURNING OF WOOD (almost smokeless)

Gday V12
The top down method is a great way to light the oven though



A tin containing charcoal soaked in 2 teaspoons of wood alcohol, some newspaper to act as a wick, a raft of large pieces, and some kindling.



Assemble. Place newspaper on the large pieces. Build a "log house" of the kindling and place the charcoal in the middle. Pile the top with twigs in this case palm fronds.



Add a lite match and its away. Building and lighting it under the chimney means it draws quickly and has little if no smoke. Added advantage is that the chimney is preheated and will draw well.



Push the whole show in the oven proper. Its hot enough to not only keep burning with little or no smoke and hot enough for the heat to be radiated from the oven walls. It burns from the top down dropping the coals onto your larger pieces of wood and the gives you a good base to start building up a fire to heat your oven.

Regards Dave

[GianniFocaccia]

Re: EFFICIENT BURNING OF WOOD (almost smokeless)

Secondly if you get a raging fire going like the youtube video shows, then you are increasing the temperature way too fast (around 500C/hr) for the refractory to cope with. This can lead to damage and the continued practice is likely to shorten the life of the refractory.

I agree. I use the top-down method to get my initial coal bed built, but end up splitting the coals into two separate, smaller fires at about 10o'clock and 2o'clock in my round oven. For the first 30 min or so I try to keep the flames on the smaller side, which means I need to feed the fire with smaller splits. I'm not certain, but I feel this may be a safer way to bring the refractory up to temperature than just blasting the biggest fire I can.

What I am still curious about is the optimum size piece of wood to put onto the fire after 30 min of heat-up time. It appears that a larger (forearm-sized piece) log only burns so fast, releasing heat at a given rate. I have been thinking that a slightly smaller piece tends to burn faster, give up its calories faster, and therefore, brings the oven up to temp faster, saving on total wood required.

Is this thinking even practical, given that smaller (thinner) pieces need replacing sooner?

John

[UtahBeehiver]

Re: EFFICIENT BURNING OF WOOD (almost smokeless)

I know you guys will get tired of me posting my fav pic of top down fire starting, but here we go again. This is how the Southern Boys in Lynchburg TN (at the Jack Daniels Distillery) do a top down fire. They use Jack as the starter and the vent you see is about 20 feet by 20 feet. That by the way is oak and they do this several times a day.

[cobblerdave]

Re: EFFICIENT BURNING OF WOOD (almost smokeless)

I agree. I use the top-down method to get my initial coal bed built, but end up splitting the coals into two separate, smaller fires at about 10o'clock and 2o'clock in my round oven. For the first 30 min or so I try to keep the flames on the smaller side, which means I need to feed the fire with smaller splits. I'm not certain, but I feel this may be a safer way to bring the refractory up to temperature than just blasting the biggest fire I can.

What I am still curious about is the optimum size piece of wood to put onto the fire after 30 min of heat-up time. It appears that a larger (forearm-sized piece) log only burns so fast, releasing heat at a given rate. I have been thinking that a slightly smaller piece tends to burn faster, give up its calories faster, and therefore, brings the oven up to temp faster, saving on total wood required.

Is this thinking even practical, given that smaller (thinner) pieces need replacing sooner?

John

Gday John
Yes im a big fan of smaller size wood rather than logs. I agree it needs more tending but I enjoy doing it and a cold beer comes in handy.
Did you notice how little charcoal is left at the end. I've hardly get any left and its more ash. That's got to be more efficient when everything burns completly.
Regards Dave

[Wozza]

Working my way through this section as I'll be curing my Pompeii in a week or so. And smoke is something that concerns me. Wouldn't want the neighbours to start complaining when I start firing her up.

I've had a wood burning stove and that smoked a little as it got started, but only for a few minutes. Once the temp was up, no problem. Likewise my chiminea. If I use a few sheets of newspaper and the smallest twigs I've got to get it started, there's a few seconds of smoke from the paper, then the heat (not the temperature, which is something different) is enough to burn clean. It's then, as Dave says, something to do while you're having a beer - just keep adding slightly larger bits of wood, keeping the heat up until the temperature is what you want. It will always burn clean. Assuming the wood is dry.

If you want smoke, then add a big chunk of wood to a low temp fire. Rather than burn, it will 'cook' and the neighbours are knocking on the front door.