Craig Kitzman Posted October 27, 2018 Report Share Posted October 27, 2018 40 cu ft Minnesota flat top fires with propane consistently hot on bottom from cone 1 to cone 11 by a cone and a half. Moving target brick has been ineffective. Ideas? Link to comment Share on other sites More sharing options...
Mark C. Posted October 27, 2018 Report Share Posted October 27, 2018 Since the forced air burners (usually two) are on bottom that is where the heat is generated . I suggest making the target bricks angle some flow upwards.-also stack the bottom tighter and looser on top to encourage heat to flow into top and slow it before it can exit Bottom with that part tighter. I feel any kiln that size with only two burners is asking for hot spots. Link to comment Share on other sites More sharing options...
neilestrick Posted October 27, 2018 Report Share Posted October 27, 2018 Two forced air burners will work just fine. That's one of the benefits of forced air- larger kilns don't need more burners. If the bottom is running hot, raise the bag wall. Half a brick may do it, it doesn't take much. Link to comment Share on other sites More sharing options...
Mark C. Posted October 27, 2018 Report Share Posted October 27, 2018 Not 100% about this but I'm not sure a true Minnesota flattop has bag walls. If so raising them will work fine.If the kiln has none try the directing target brick to shoot that flame upwards at a angle . Link to comment Share on other sites More sharing options...
Rex Johnson Posted October 29, 2018 Report Share Posted October 29, 2018 I have the same issue with my flat top downdraft. Hot down by the burners, cooler on the top shelves by at least a cone. I'm finding that besides fiddling with the flue and blower flaps/gas, when it gets close to desired temp, I'll cut the gas down 1/3rd and adjust flaps for optimal flame and let it stabilize (essentially soak). Turning down the gas (hot burners) tends to even out the temp top to bottom and still reach the target temp. Hope that helps. Link to comment Share on other sites More sharing options...
PatIsGone Posted October 30, 2018 Report Share Posted October 30, 2018 J.T. Abernathy in MI had burners half way up the kiln also. His theory was put the heat where you need it. Supposedly a 30% decrease in fuel usage as opposed to similar kiln - actually as compared to Marc Ward's numbers. Would be interesting to see one with and one without and see the difference. Hmmm. I feel an empirical data collection moment coming on... If you added a burner up half way up, theoretically it would only have to increase the cost of firing by the additional electricity to run the blower. Making an additional burner would be in initial outlay, but if it cut costs, just a matter of time for break-even and then savings. ... Just brainstorming for ya. Link to comment Share on other sites More sharing options...
Magnolia Mud Research Posted October 30, 2018 Report Share Posted October 30, 2018 Part of the problem in many of the gas kilns is that the exit hole is too big. Another is that the stacking does not allow the gases to circulate within the kiln. The burners should be causing the gas inside the kiln to circulate. Of all the kiln books I have examined (10+ I think) only Mel Jacobson's "21st Century Kilns" has addressed the circulation issue. Nils Lou's book hinted at the problem and did identify the oversized exit hole as being a cause of both wasted fuel and poor temperature uniformity. LT Link to comment Share on other sites More sharing options...
neilestrick Posted October 30, 2018 Report Share Posted October 30, 2018 @Craig Kitzman can you tell us more about the kiln? Does it have a bag wall? Power burners? Link to comment Share on other sites More sharing options...
Mark C. Posted October 31, 2018 Report Share Posted October 31, 2018 I assumed that his kiln has the original liquefied (propane )power burners. Those really had great output and turbulence . Lets see if he is still here for an answer Link to comment Share on other sites More sharing options...
Craig Kitzman Posted October 31, 2018 Author Report Share Posted October 31, 2018 More information on cold top in Minnesota flat top: 2 sk 1ss liquified propane burners at 3lbs at regulator. Hot on top by a cone or two until cone 1 then abruptly switches to hot on the bottom as indicated. I've moved target brick toward burner incrementally but this also exacerbates the hot top during early stages . Link to comment Share on other sites More sharing options...
Mark C. Posted November 1, 2018 Report Share Posted November 1, 2018 For me I could care less about cone 1 temps going to cone 10.I need more eveness at cone 8 or 9 before 10. Early hot tops make sense as thats where the heart goes before kiln starts to breath. There has been a lot written on flat tops-lois book and Mel Jacobson if I recall as well. I'm suggesting an angle to the target brick not closer to direct heat up near the top end of temp when the glaze is melting. This kiln has no bags walls right? Mark Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.