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[terpjr]

Happy Groundhog and Super Bowl Sunday everyone,
I have seen, over the course of quite a few message strings, several people mention that they do not pack their furnace full of wood.  They have said that packing the furnace full wastes wood.
I have always packed mine full but now am re-thinking this.  The people on this forum all seem very knowledgeable and scientific about their furnaces...so...
is it more efficient not to pack your firebox full?
Is this still true for long burns?
What is the reasoning behind this?

Thanks in advance.

[slimjim]

By not packing the boiler full of wood you are allowing a better mix of fresh air into the burn chamber for a cleaner burn, smoke is nothing but unburned fuel, when you fill it full and it smokes like a banchi, you are wasting fuel, much better off fueling to the outside temps and demand, long burn times with full loads are great but try putting less wood in each time you load and load more often and you will see the difference in how much you burn.

[ITO]

 Enough people claimed this worked and so I tried it also, for my system it does make a noticeable difference. In very cold temps I have to fill it full and also work gets in the way and I have to fill it full because we won't be back for 12 hours somedays. I can tell it burns better with a smaller load of wood though and I load it this way whenever I can now.

[netwerx-r-us]

I mirror Ito's comments 100%, I also tried this , when i pack it full i may get 8-12 inches of coals piled up and doesnt burn as well , I go 1/2 to 3/4 full and let that burn down before adding more, there are days when I'm not here I go full , course I walk out and poke the fire every 2-3 hours out of habit anyway so  its not a big deal while I'm here

[hondaracer2oo4]

Unlike other forms of heating devices such as gas, oil, pellet, coal stoker etc all of the fuel needed for the 12 hour burn(or until your next loading) is all loaded in the firebox at once. As the wood is heated it begins to off gas(smoke) which is what you are actually burning when you have a fire, not the wood itself. As the boiler sits at idle(inefficient) the wood still is being heated by the coals to the point of off gassing. When the boiler comes out of idle you will see a large dense plume of smoke which is a lot of fuel that is wasted. When the wood up high in the burn chamber  makes it down to the bottom of the burn chamber and everything below it has burned it doesn't have nearly the amount of BTU's left in it that the wood at the bottom had when started. Thus that wood disappears very quickly. At least thats my take on it!

[automan77]

I make sure I leave plenty of spaces for air flow. Less smoke and cleaner burn.

[capitalpyro]

much better off fueling to the outside temps and demand, long burn times with full loads are great but try putting less wood in each time you load and load more often and you will see the difference in how much you burn.

I couldn't agree more with this.