kraythe Posted September 26, 2018 Report Share Posted September 26, 2018 I am currently firing some high fire stuff and my gas kiln is seriously stalled and wont move. I have tried adjusting the propane, opening valves, adjusting airflow and it just stubbornly hangs at the same temp. Any suggestions? I need to get it to about 1290 to get just over cone 10. The kiln is a 2 burner olympic torchbearer. Link to comment Share on other sites More sharing options...
Mark C. Posted September 26, 2018 Report Share Posted September 26, 2018 open the damper-do you have a digital pyrometer so you see it going up down or stalled???? maybe you are pumping in to much gas? A few details would help Link to comment Share on other sites More sharing options...
liambesaw Posted September 26, 2018 Report Share Posted September 26, 2018 My gas kiln usually stalls when I'm feeding too much gas. But it could be anything! Mine is propane so I really have to ride a thin line on pressure otherwise the tank will freeze up. Link to comment Share on other sites More sharing options...
kraythe Posted September 26, 2018 Author Report Share Posted September 26, 2018 Digital pyrometer, top draft, only very slightly covered for light reduction. Stalled or moving extremely slowly, burners all the way open. I can try backing off on the propane, its almost full bore right now. and not doing much. Link to comment Share on other sites More sharing options...
kraythe Posted September 26, 2018 Author Report Share Posted September 26, 2018 1 minute ago, liambesaw said: My gas kiln usually stalls when I'm feeding too much gas. But it could be anything! Mine is propane so I really have to ride a thin line on pressure otherwise the tank will freeze up. I will back off on the propane. I use tanks 4 x the size of your barbequeue tank and they dont freeze. Link to comment Share on other sites More sharing options...
liambesaw Posted September 26, 2018 Report Share Posted September 26, 2018 Just now, kraythe said: I will back off on the propane. I use tanks 4 x the size of your barbequeue tank and they dont freeze. Twice the size of my tank, I use 40lb with a high pressure regulator. My tanks only freeze up when they are opened up too much and the tank is getting empty. Link to comment Share on other sites More sharing options...
kraythe Posted September 26, 2018 Author Report Share Posted September 26, 2018 looks like backing off the gas worked, I am now over my thermocouple temp. Hit target I think, time to cool SLOWLY. *crosses fingers on this temmoku* thanks Link to comment Share on other sites More sharing options...
liambesaw Posted September 26, 2018 Report Share Posted September 26, 2018 Woo! Link to comment Share on other sites More sharing options...
Mark C. Posted September 27, 2018 Report Share Posted September 27, 2018 (maybe you are pumping in to much gas?) THIS A COMMON MISTAKE . Its easy to think more gas should raise temp but often less is more. The sweet spot is a correct air to gas ratio. After you find that spot only use the damper to control reduction. Glad it worked out Link to comment Share on other sites More sharing options...
kraythe Posted September 27, 2018 Author Report Share Posted September 27, 2018 thanks all. We will see how the pots come out. I am just a hobbyist after all Link to comment Share on other sites More sharing options...
kraythe Posted September 27, 2018 Author Report Share Posted September 27, 2018 My best kiln firing ever for this hobbyist. A couple of minor glaze flaws in some pieces but I am SOOO happy. :) Thanks for all the help The reduction came out magnificent. Link to comment Share on other sites More sharing options...
liambesaw Posted September 27, 2018 Report Share Posted September 27, 2018 Beautiful temmoku Link to comment Share on other sites More sharing options...
kraythe Posted September 27, 2018 Author Report Share Posted September 27, 2018 Thank you very much. 34 minutes ago, liambesaw said: Beautiful temmoku Link to comment Share on other sites More sharing options...
neilestrick Posted September 27, 2018 Report Share Posted September 27, 2018 @kraythe The thing to remember with a gas kiln is that you're not just trying pump heat into the kiln. Rather, you're moving heat through the kiln. The heat comes in, is transferred to the ware, and moves out, to be replaced by new heat. It's a flow, and your kiln can only manage a certain volume of flow. Pump too much gas or air into it, and the flow bogs down. Link to comment Share on other sites More sharing options...
Rex Johnson Posted October 2, 2018 Report Share Posted October 2, 2018 Yeah, counter to common sense, turning the gas down will indeed help the heat rise. But it's all about the air/fuel mixture and the flue draw. I have to watch my Olympic bottom burner kiln real close. Bisque will over fire in a few minutes if I'm not on the ball... Link to comment Share on other sites More sharing options...
Bill Kielb Posted December 4, 2018 Report Share Posted December 4, 2018 A way to think of this is at some point you will have the exact air / fuel ratio through your burners to provide the most heat possible at a given pressure setting. So too much air through the burner primary air port for a given amount of gas results in a lean mixture with less output. Too much gas and not enough air through the primary air port results in an overly rich mixture with unburned fuel and again peak burner output is reduced. you have atmospheric burners so they rely on an air shutter position (on the burner) as well as gas pressure and injection through the nozzle to influence the amount of air sucked in by Venturi effect through the primary air port. So without complicating things it is 1) too much air, 2) too much gas or 3) just right with respect to speed, efficiency and gas pressure. so if I had to simplify I would try and set the primary air shutter on my burner at its best setting (heat output) for top pressure operation. Then I would close my top damper slowly until I begin reduction or my temperature rise starts to decrease. Just prior to this point is where I can get the maximum heat from my burners while wasting the least amount of heat from my kiln. Establishing a known good top end helps simplify getting the most from your burners and kiln when you need it. This is an over simplification but usually a decent compromise for many potters and is something they can do easily while simply moving their top damper a bit in and out at the end of the firing. As they desire. just one way we approach this until folks can become more familiar and comfortable with how burners work etc.... Link to comment Share on other sites More sharing options...
Rex Johnson Posted December 13, 2018 Report Share Posted December 13, 2018 Yes, gas kilns are all about the fire triangle, oxygen/fuel/heat. If you keep that in mind when firing you're going to get a better idea of what's going on during a firing. But we also have one more thing to consider, and that's draw, how the fuel and heat is being pulled through the kiln from burners to flue. Until one gets it all dialed in (kiln schedule), it's a process that takes attention. I assume commercial gas kilns with automated devices help mitigate the guess work. But I rememeber over-firing our college kiln first time I tried Link to comment Share on other sites More sharing options...
cbtechnicalsources@yahoo.c Posted July 3, 2020 Report Share Posted July 3, 2020 Converted kiln to propane. Can't get temp past 2150f to reach cone 10. Draft hole with damper located at bottom of kiln. Should i have made cutout at top of chimney with damper instead for better draw? Link to comment Share on other sites More sharing options...
Bill Kielb Posted July 3, 2020 Report Share Posted July 3, 2020 6 hours ago, cbtechnicalsources@yahoo.c said: Converted kiln to propane. Can't get temp past 2150f to reach cone 10. Draft hole with damper located at bottom of kiln. Should i have made cutout at top of chimney with damper instead for better draw? We really need a picture if you have a draft hole at the bottom and no chimney. Many converted downdrafts have an internal chimney so the opening is still at the top of the kiln. Anyway, it’s not clear to me how your flue gases exit the kiln at the bottom without melting the outside so a picture would probably spark some thought. Link to comment Share on other sites More sharing options...
Mark C. Posted July 4, 2020 Report Share Posted July 4, 2020 Cut out at bottom is fine as long as you have a chimney -You do not give us enough info to help much If the chimney is tall enough it will draw fine. I think what maters more is the flow needs to go up then down no matter where the flue is. That means the flue is in bottom -wether the chimmney is inside kiln or outside.Often turning gas down is best as many think blasting more gas makes for more heat. Link to comment Share on other sites More sharing options...
Hulk Posted July 4, 2020 Report Share Posted July 4, 2020 Converted from natural gas? Repurposed electric? Link to comment Share on other sites More sharing options...
Mark C. Posted July 4, 2020 Report Share Posted July 4, 2020 2 hours ago, Hulk said: Converted from natural gas? Repurposed electric? Usually that means an electric (I call them trash can kilns as they are round like trash cans) Link to comment Share on other sites More sharing options...
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