Michael Roest Posted August 24, 2011 Report Share Posted August 24, 2011 Hello! We have recently built a gas kiln which uses natural gas with Ward forced air burners. We are in the process of discovering how to best operate our kiln and would love additional input from potters that use forced air burners as we are most familiar with venturi propane burners. Information about your experiences would really help us. At lower temps that you would go into a clay body reduction we aren't getting flames out of the spy holes - after pushing the damper in and increasing the gas. What kind of adjustments do you make in order to create an effective reducing environment? We are unsure of how the blower and the air vents play a role in this as we are used to venturi burners with propane. Any thoughts? I am hoping to develop a good clay body reduction and some reduction that shinos need (staring around cone 012-010). Downdraft kiln with chimney 2 Ward forced air burners If you fire using similar equipment, it would be great to hear your ideas. I hope all is well! Link to comment Share on other sites More sharing options...
Marcia Selsor Posted September 6, 2011 Report Share Posted September 6, 2011 I used to body reduce at ^09-04. If you put a dry piece of wood in front of the spy hole and it doesn't ignite, then you are in reduction..lack of oxygen. You should keep the damper open a little bit, like 1/8-1/16 of the total opening depending on the draft and altitude, etc. You'll just have to fire it a few times to see how it goes. Marcia Link to comment Share on other sites More sharing options...
phill Posted September 12, 2011 Report Share Posted September 12, 2011 I might be able to help. Take it with a grain of salt. I went to a school which uses forced air (dont know brand). Two burners at the back of the kiln and its a Donovan car kiln. Pretty big too. We candle starting from supper time and on into the night with a medium strength flame. what does that look like? umm...try having the flame go really fast (by turning the blower on about 1/4 full speed, and playing with the gas), then tone it down quite a bit. Anyway, candle over night, and come back after breakfast about 8am. check kiln (obviously after firing your own kiln you will learn more every time, like geez i should have turned up that flame last night during candling because now im going to be here FOREVER!!!). we have a heat probe so we have some idea of temperature. but once we get to the kiln in the morning we blast the burners and try to get that heat up to redux zone. then slow down the kiln and redux by simply turning the gas valve to give more gas. the flame will go from super forced and powerful flame to ...hmm how to describe this... not as powerful? haha, just play with it. i find you can check your flame within 30 seconds of adjusting the gas valve. you should notice a color change in the flame from the burner port too. anyway, check the peep holes. we keep our bottom peep (we have two, top and bottom) open because our kiln fires better. if you have a nice flame coming out like a dragon is breathing fire you are good! if you dont have flame coming out or it is kinda weak i would turn up the gas some for reduction. good luck i hope this helped some! Link to comment Share on other sites More sharing options...
Marcia Selsor Posted October 1, 2011 Report Share Posted October 1, 2011 I would recommend adjusting the damper also. This will help get the licking flame to come out the bottom peephole. Marcia Link to comment Share on other sites More sharing options...
neilestrick Posted October 5, 2011 Report Share Posted October 5, 2011 Proper reduction is achieved through a combination of adjustments to the blower speed, blower intake, gas pressure and damper. It will take several to many firings to figure out what settings will work best, and they will change slightly for every firing, depending on how the kin is loaded, weather conditions, etc. This is all very simplified, but first set the gas pressure high enough that the kiln is climbing at the rate you want. Then set the blower speed. It's been my experience that you will rarely need to have the blower speed at 100%. You'll be able to tell if it's too high because the flame will seem too 'violent'. 50%-75% will probably work fine. Then cover the blower intake to get the desired reduction flame coming out of the burner. Last, adjust the damper until there is the slightest amount of back pressure coming out the bottom spy hole. I like to set all this so that the kiln stalls out and stops climbing in temperature during body reduction (cone 08 or so). After 45 minutes, open the blower intake so that the flame is in a light reduction or neutral state, and adjust the damper again to keep just a touch of flame out the bottom spy hole. It may take adjusting everything several times until you get it right. There's a lot of trial and error when learning to fire a new kiln. Link to comment Share on other sites More sharing options...
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