Fire box material and secondary air tube location

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ddahlgren

Minister of Fire
Apr 18, 2011
555
SE CT
I am thinking about adding the ability to burn wood to an existing coal stove for chilly nights and warm days. Coal works very well when below 40 continually but can be a challenge in the 60's during the day and 40 at night. Without getting into the details of burning coal here are my questions.

Currently the stove designed for coal is a steel welded box with cast iron fire pot a small removable baffle that covers half the flue outlet grates under the fire pot that you shake to remove ashes. Primary air comes in below the grates in ash pan area with a small secondary one just above the firepot I added to help burn off volatile gases when loading the stove.

Stove has a metal firepot with no refractory of any kind and very difficult to add. Does wood need it as my previous woodstove was lined the brick with a brick top baffle as well.

Will a metal upper baffle live for occasional use of small fires for maybe an hour or two to take the chill out and would be removable for coal burning where it gets in the way though testing may say something else too.

Location of secondary burn tube I have in mind would be at the leading edge of upper baffle as it was in my wood stove where the gases have to turn the corner to go around the baffle to get to the flue outlet. Obviously I have to fab the secondary burn tube and baffle along with mounting points.

Last for now optimum angle for holes in burn tube? Straight down angled towards window or what?

I have burned some wood in the stove with no mods and more of a controlled smoke dragon as never intended to burn wood so no real provisions to do a good job of it other than to start a kindling fire let it get hot with some coals from wood then start adding coal. Once that lights off and full just add coal and remove ashes every 12 hours. The catch is there is a limit as to how low you can go temp wise and warm days 55-60F the windows are open burning coal for no reason so have a little heat at night.
 
Well, while many modern stoves are rather simple in construction, they're actually engineered to operate rather precisely. So the volume of gasses, temp. and volume of 2ndary air, and volume of primary air when shut down, and other factors are all calculated to work together to control an efficient burn. It may be just bricks, steel tubes, and maybe a kaowool blanket, but there's actually alot going on in there.

Why not give it a try I guess, but results may be not bear the kind of fruit you wish. Might get lucky though!
 
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