Crusty Posted January 13, 2020 Report Share Posted January 13, 2020 we found a used kiln that would be perfect for a gas conversion ''downdraft''.. it is 23.5 in wide and 22 tall 3 sections - im pretty sure thats close to 5 CF which is a little bigger than the J 230 we have now.. i like the design of the Geil gas kilns , seems like that is the best way to go.. i see alot of conversions being heated from the bottom on the side but im not a fan of that as there tends to be so much wasted space or am i missing something and not thinking this through fully? what about heating from the top section on the side since its a downdraft? i plan on using a Ward venturi type burner or 2 .. so if i heat from the bottom i would need a 2.5 to 3 inch hole and if i use 2 burners that would double .. if i do a burner on the side i lose 3 in plus i would have to redirect the heat upward and build a chimney flue inside "Simon Leach" style which im not sure that is best ... i know both ways work but which way is better for reduction ? i have been watching a lot of videos on conversions and the results vary quite a bit.. the folks using bottom burners seem to do better but their kilns seem to be mostly custom built arch tops and a lot bigger .. Chimney- i want it outside the kiln to save as much internal space as possible. a 6ft tall chimney seems to be standard on conversions for some reason.. i could use some help with this as all of the chimney holes are different sizes. i have a full roll of cerawool in the basement, i could use that with some chicken wire or something to help hold a form... it will be outdoors. thanks for any help and advice.. Link to comment Share on other sites More sharing options...
Mark C. Posted January 14, 2020 Report Share Posted January 14, 2020 The reason kilns are heated from the floors in downdrafts are the heat goes up and is pullled down thru the wares to the exit flue . It really the best way as you get the to use the heat twice sort of speak. Since this is your 1st kiln you will learn a lot and make lots of mistakes-like learning to drive (use an old car) just expect it to be wildly uneven in temps. Trying to reinvent the wheel may also not help. I constructed a down draft salt kiln two years ago at a workshop and posted photos here. That was a coffin larger electric . I had 4 burners on the floor and made the downdraft flue inside the rear of chamber-(the stack ran thru the lid which came off to load and unload) worked ok but salt eats everything up fast. The biggest issue is these kilns are super small and as you noted space is needed for the combustion and exit flue Link to comment Share on other sites More sharing options...
neilestrick Posted January 14, 2020 Report Share Posted January 14, 2020 Do a lot of searches here on the forum and you'll find a lot of information about how to make that type of kiln work. The main issue is that there's not enough space inside for the kiln to breathe. I recommend using 15" shelves rather than the 20" shelves that you would use as an electric. Link to comment Share on other sites More sharing options...
Crusty Posted January 15, 2020 Author Report Share Posted January 15, 2020 Thanks Marc and Neil. I have been doing some extra research and contacted Ward with CF size and a 2 burner system.. He said the kiln must be sealed up pretty good and keep shelves at least 2.5 to 3 inches from kiln walls for best air flow. I think 15'' like neil suggested ill be perfect, also do not over pack the kiln...Out side chimney is best but did not give a diameter or stack height.. so i need to figure that out.. so the plan rite now is to kill all the angles in the octagon shape by putting a layer of cerawool in and that should help with air leaks and seal it up better... 2 Floor burners possibly 3 as i would rather be over powered than under.. "i see alot of conversions have trouble raising temp after 1500F when they go into reduction, maybe a extra burner will help? Link to comment Share on other sites More sharing options...
akilspots Posted January 16, 2020 Report Share Posted January 16, 2020 checkout matt raue on instagram (https://instagram.com/mattraue/) he's been firing a few conversion kilns with jeff shapiro and posting lots of videos and info on the firings. Link to comment Share on other sites More sharing options...
Crusty Posted January 24, 2020 Author Report Share Posted January 24, 2020 On 1/16/2020 at 1:58 PM, akilspots said: checkout matt raue on instagram (https://instagram.com/mattraue/) he's been firing a few conversion kilns with jeff shapiro and posting lots of videos and info on the firings. Thanks.. i have been everywhere but instagram .. Link to comment Share on other sites More sharing options...
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