Decided I wanted a smaller stove for the next month or two, so I went out and bought one for $13.50 and installed it in five minutes today. It was in the form of 9 firebricks @$1.50 (full 2-1/2" thick size). I owe a thank uuu to the artist~formerly~known~as~pook for the inspiration he provided as the odd man out (shocking!) in a recent thread: https://www.hearth.com/econtent/index.php/forums/viewthread/58789/
I stacked up three bricks (on edge) making a new 9" by 13.5" wall on each side of my firebox. This shortened its width from 21" to 16" to make it more efficient for smaller fires. (Too bad I had already brought in some 18" wood, but I have plenty of chunks and junks to burn.) Because I have a downdraft-type stove, I need a good bed of coals in the back center of the firebox to achieve secondary combustion. With the walls now closed in, as the shorter splits begin to coal they can no longer fall away to the sides and spread out on the floor of the firebox.
The other three bricks were used to make the floor of the firebox. Because I have a grate and ashpan, the hot coals tend to break up and fall through the grate, rather than build up into the thick coal bed I need. So with a nice cushion of ash below them, I centered the three bricks just below the grate and pushed right to the back of the stove, so there is no longer any air space there. I discovered the advantage of this by accident last winter after neglecting to empty the ashes - my coal bed formed more quickly, and lasted longer, with a deep pile of ash left below. I think this stove should have been designed with no ashpan.
So I reduced the volume of my firebox by about 15%, and added to the thermal mass of the stove by about 15%. But the area reduction of the rear half of my firebox floor, where it really counts for this type of downdraft stove, was by about 25%. And it really showed in my burn tonight: the coals, confined to a smaller area and unable to trickle down into the ashpan, built up very fast. I was able to close the bypass and burn smoke in record time, with no stalling!
I stacked up three bricks (on edge) making a new 9" by 13.5" wall on each side of my firebox. This shortened its width from 21" to 16" to make it more efficient for smaller fires. (Too bad I had already brought in some 18" wood, but I have plenty of chunks and junks to burn.) Because I have a downdraft-type stove, I need a good bed of coals in the back center of the firebox to achieve secondary combustion. With the walls now closed in, as the shorter splits begin to coal they can no longer fall away to the sides and spread out on the floor of the firebox.
The other three bricks were used to make the floor of the firebox. Because I have a grate and ashpan, the hot coals tend to break up and fall through the grate, rather than build up into the thick coal bed I need. So with a nice cushion of ash below them, I centered the three bricks just below the grate and pushed right to the back of the stove, so there is no longer any air space there. I discovered the advantage of this by accident last winter after neglecting to empty the ashes - my coal bed formed more quickly, and lasted longer, with a deep pile of ash left below. I think this stove should have been designed with no ashpan.
So I reduced the volume of my firebox by about 15%, and added to the thermal mass of the stove by about 15%. But the area reduction of the rear half of my firebox floor, where it really counts for this type of downdraft stove, was by about 25%. And it really showed in my burn tonight: the coals, confined to a smaller area and unable to trickle down into the ashpan, built up very fast. I was able to close the bypass and burn smoke in record time, with no stalling!
