Kleipots Posted August 5, 2011 Report Share Posted August 5, 2011 Hello everyone This is my very first post. I have a problem with my kiln and my hopes flared up as I read all the responses and advice given about Ruti's problem. My kiln is electric though, not gas. I have a quite an old Harrison Meyer Limited electrical toploader kiln (2.63 Cu ft.), single phase with a CAHO SR-T901 temperature controller. Being in South Africa our electricity pushes through 220/240 volts I had an electrician from the city council over at my workshop who confirmed that , that is indeed what they are supplying. The specs on the kiln says maximum temperature of 1300 C/cone10 (4.8kw). The dial on the Controller also shows a maximum of 1300 C. When the kiln is switched on we switch everything else off;pool pump, geyser (water cylinder), etc. Just a good habit according to our electrician. It runs off an 10 meter electrical cable that is connected straight into the DB board which is a very thick industrial cable installed by a qualified electrician and also got the approval of the city official mentioned earlier. For 17 years it has fired to cone 04 (1060 C) with no problems at all. A normal glaze firing takes about 6 hours, cools down overnight and ready to unpack the following morning. Perfect. My problem is that I want to fire to 1240 C, but the kiln only reaches 1146 C and then goes no further. We switch on the kiln with the automatic controller set to switch off at 1240 C. It takes 8 hours to reach about 1120 C and then another 2 hours just to reach 1146 C. Then it goes no further. Once when I left it on for another hour. It just stayed on at 1148 C after which it started to drop slightly but just one or two degrees, that is when I switched it off. Our local potter supplier's electrician has checked out the cabling, replaced the elements and thermocouple with absolutely no luck. There are no cracks in the kiln bricks. I have contacted the temperature controller suppliers to find out if there is any way to verify that the temp controller is working properly. They say that if the controller hasn't switched off by itself at 1148, the problem is with the kiln and not the controller. There is a tiny "reset " dial on the face with a +- maximum and minimum setting, does anyone know what is it for? Could it help to turn that up or down? It is at "11 o'clock " at the moment. I am happy with the bisque and earthernware glaze firings and the kiln does pull 4.8 kilowatt and I checked that all the elements are working. I have been battling with this problem for a few months now and as I mentioned I have replaced just about everything except for the kiln itself and the temp controller, Any ideas? Link to comment Share on other sites More sharing options...
Pres Posted August 5, 2011 Report Share Posted August 5, 2011 Hello everyone This is my very first post. I have a problem with my kiln and my hopes flared up as I read all the responses and advice given about Ruti's problem. My kiln is electric though, not gas. I have a quite an old Harrison Meyer Limited electrical toploader kiln (2.63 Cu ft.), single phase with a CAHO SR-T901 temperature controller. Being in South Africa our electricity pushes through 220/240 volts I had an electrician from the city council over at my workshop who confirmed that , that is indeed what they are supplying. The specs on the kiln says maximum temperature of 1300 C/cone10 (4.8kw). The dial on the Controller also shows a maximum of 1300 C. When the kiln is switched on we switch everything else off;pool pump, geyser (water cylinder), etc. Just a good habit according to our electrician. It runs off an 10 meter electrical cable that is connected straight into the DB board which is a very thick industrial cable installed by a qualified electrician and also got the approval of the city official mentioned earlier. For 17 years it has fired to cone 04 (1060 C) with no problems at all. A normal glaze firing takes about 6 hours, cools down overnight and ready to unpack the following morning. Perfect. My problem is that I want to fire to 1240 C, but the kiln only reaches 1146 C and then goes no further. We switch on the kiln with the automatic controller set to switch off at 1240 C. It takes 8 hours to reach about 1120 C and then another 2 hours just to reach 1146 C. Then it goes no further. Once when I left it on for another hour. It just stayed on at 1148 C after which it started to drop slightly but just one or two degrees, that is when I switched it off. Our local potter supplier's electrician has checked out the cabling, replaced the elements and thermocouple with absolutely no luck. There are no cracks in the kiln bricks. I have contacted the temperature controller suppliers to find out if there is any way to verify that the temp controller is working properly. They say that if the controller hasn't switched off by itself at 1148, the problem is with the kiln and not the controller. There is a tiny "reset " dial on the face with a +- maximum and minimum setting, does anyone know what is it for? Could it help to turn that up or down? It is at "11 o'clock " at the moment. I am happy with the bisque and earthernware glaze firings and the kiln does pull 4.8 kilowatt and I checked that all the elements are working. I have been battling with this problem for a few months now and as I mentioned I have replaced just about everything except for the kiln itself and the temp controller, Any ideas? Sounds like to me you are pushing this kiln beyond its limits. Maybe you should look at cone 6 for your max firing with a cone 6 body. Many of the same attributes had a 10 can be met with 6. The only other answer I would have is maybe insulating the top of the kiln with some fiber insulation blanket, this may give you a few more degrees, but at what cost? Thicker lid brick may help, but as I said before-I think it is reachiing its limit. Link to comment Share on other sites More sharing options...
Arnold Howard Posted August 5, 2011 Report Share Posted August 5, 2011 I am happy with the bisque and earthernware glaze firings and the kiln does pull 4.8 kilowatt and I checked that all the elements are working. Have you tested the kiln with an ammeter to determine whether the kiln is pulling the amperage listed on its electrical data plate? Especially common in the summertime, low voltage can lower the firing capacity of electric kilns. Firing the kiln for long periods at the stalling temperature is very hard on the elements, by the way. That struggle causes more wear than firing at lower temperatures. Sincerely, Arnold Howard Paragon Industries, L.P., Mesquite, Texas USA ahoward@paragonweb.com / www.paragonweb.com Link to comment Share on other sites More sharing options...
Kleipots Posted August 6, 2011 Author Report Share Posted August 6, 2011 I am happy with the bisque and earthernware glaze firings and the kiln does pull 4.8 kilowatt and I checked that all the elements are working. Have you tested the kiln with an ammeter to determine whether the kiln is pulling the amperage listed on its electrical data plate? Especially common in the summertime, low voltage can lower the firing capacity of electric kilns. Firing the kiln for long periods at the stalling temperature is very hard on the elements, by the way. That struggle causes more wear than firing at lower temperatures. Sincerely, Arnold Howard Paragon Industries, L.P., Mesquite, Texas USA ahoward@paragonweb.com / www.paragonweb.com I have not checked with a meter but we have prepaid electricity and we can check how many Kilowatts is being used at any given time, with all other appliances off it does show 4.8 Kw when the kiln is on which is what the data plate on the kiln says. But I will do as you say as soon as I get hold of an ammeter. Thanks! Link to comment Share on other sites More sharing options...
lyn Posted August 6, 2011 Report Share Posted August 6, 2011 I am happy with the bisque and earthernware glaze firings and the kiln does pull 4.8 kilowatt and I checked that all the elements are working. Have you tested the kiln with an ammeter to determine whether the kiln is pulling the amperage listed on its electrical data plate? Especially common in the summertime, low voltage can lower the firing capacity of electric kilns. Firing the kiln for long periods at the stalling temperature is very hard on the elements, by the way. That struggle causes more wear than firing at lower temperatures. Sincerely, Arnold Howard Paragon Industries, L.P., Mesquite, Texas USA ahoward@paragonweb.com / www.paragonweb.com I have not checked with a meter but we have prepaid electricity and we can check how many Kilowatts is being used at any given time, with all other appliances off it does show 4.8 Kw when the kiln is on which is what the data plate on the kiln says. But I will do as you say as soon as I get hold of an ammeter. Thanks! This is more of a problem than it first appears! I have an old L&L J14 with the same problem. At this point I suggest you make sure the kiln shelves are at least 1" from the sides when you load and at least try to contact the manufacturer (if they still exist!) they might have other suggestions. In the U.S. for example, voltage can vary quite a bit and kilns that work fine at 220V won't get to temperature at 208V. Good Luck Link to comment Share on other sites More sharing options...
Arnold Howard Posted August 6, 2011 Report Share Posted August 6, 2011 At this point I suggest you make sure the kiln shelves are at least 1" from the sides when you load and at least try to contact the manufacturer (if they still exist!) they might have other suggestions. That is a good suggestion. Having the correct shelves improves heat distribution. Sincerely, Arnold Howard Paragon Industries, L.P., Mesquite, Texas USA ahoward@paragonweb.com / www.paragonweb.com Link to comment Share on other sites More sharing options...
Guest HerbNorris Posted August 6, 2011 Report Share Posted August 6, 2011 Has this kiln EVER been fired as high as cone 10? I ask, because as Pres suggested, you might be asking too much of the kiln. You might need more than 4.8kW to make it. Link to comment Share on other sites More sharing options...
Kleipots Posted August 7, 2011 Author Report Share Posted August 7, 2011 Thanks for all the input! I guess I am being a little too optimistic. The kiln has never been fired to cone 10. So if more than 4.8 Kw is required I suppose it can't. I have, however left out a small but probably very important detail. It is a top loader and the lid does lift about a 1/4 inch and even more at the higher temperatures. The gap is much less on the side where the hinge is, so the lid does not "float" evenly. I have tried to lessen the gap on one side by putting strips of kaolin wool on the rim to try keep some of the heat in. It is not really effective -I am not even sure if the gap is reduced . Is it normal for the lid to lift like that? would it help to put some kind of latch on the kiln too keep the lid from rising? When I do a glaze firing I insert bungs in front and on top when the temperature reading is about 800 C. Link to comment Share on other sites More sharing options...
Guest HerbNorris Posted August 7, 2011 Report Share Posted August 7, 2011 Yes, it is "normal" for lids to lift like that, because of the force of the rising hot air; at firing temperatures the force can really be something, as you have seen. I've always been amazed at how much power the heat seems to have at those high temps, it makes me appreciate firefighters even more. Many kilns have metal latches that are used to hold the lid closed, to prevent heat loss. Link to comment Share on other sites More sharing options...
Arnold Howard Posted August 8, 2011 Report Share Posted August 8, 2011 Thanks for all the input! I guess I am being a little too optimistic. The kiln has never been fired to cone 10. So if more than 4.8 Kw is required I suppose it can't. I have, however left out a small but probably very important detail. It is a top loader and the lid does lift about a 1/4 inch and even more at the higher temperatures. I agree about the wattage for that size kiln. The lid is rising at the front because the firebricks in the walls are expanding as they get hot. That places pressure against the lid, causing it to rise. You can solve this problem by enlarging the holes in the hinge that hold the rod. Lift up the back of the lid. If it already has about 1/8" of play, then the hinge may be bent, causing the lid to bind instead of rise at the hinge rod. Sincerely, Arnold Howard Paragon Industries, L.P., Mesquite, Texas USA ahoward@paragonweb.com / www.paragonweb.com Link to comment Share on other sites More sharing options...
Marcia Selsor Posted August 8, 2011 Report Share Posted August 8, 2011 if you have fired this kiln to ^04 for seventeen years, when did you last change elements? may be time, no? marcia Link to comment Share on other sites More sharing options...
lakesidepottery Posted November 6, 2011 Report Share Posted November 6, 2011 Hi, We have created a couple of tutorials on how to troubleshoot kiln problems. See links below and hope it is useful. http://lakesidepottery.com/Pages/Pottery-tips/computerized-electric-kiln-troubleshooting-reference-guide.htm http://lakesidepottery.com/HTML%20Text/Tips/Firing.htm Kindly, Patty and Morty Link to comment Share on other sites More sharing options...
Benhim Posted November 6, 2011 Report Share Posted November 6, 2011 if you have fired this kiln to ^04 for seventeen years, when did you last change elements? may be time, no? marcia That's what came to my mind, a kiln will fire to low temperatures for years with the same elements, but the higher temperatures are out of reach for an old spent element on it's last leg. I've also read many peoples blogs about firing to cone 10 in an electric kiln. The people who are really serious about it change out their elements to a thicker gauge wire element that can handle the temperature. I'd like to hear feedback from a manufacturer about upgrading elements. I've moved my studio twice now in the last couple of years. There has been no change in my kiln itself, but the power supplied to my house has changed drastically. The first place it was had old wiring and I got part way into set up and changed my mind and moved. The second place I had the kiln it was with in 3 feet of the main leads that come into the house. The leads were the new larger size wire, and I had no problems plenty of power. I had to move to a new place again which had smaller leads from the early '50s. I've realized that even cone 6 is difficult for my kiln at this location. It's getting there but it's taking many hours longer than it should. My wiring is all spec, exactly what's supposed to be there and my kiln is again 3 feet from the power leads. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.