olpupi Posted July 1, 2017 Report Share Posted July 1, 2017 I thought my Cress ET28 had been working fine as cones confirmed it was reaching Cone 6 in the usual amount of time and using the usual amount of energy. But after starting a bisque load with the first step being 180/hour to 180, no hold, I noticed that 20 minutes after starting it had reach 193 and the relays were still cycling off and on. I restarted and this continued to happen; not stopping at the set point. I unplugged the kiln and re-entered the firing program with same results. I re-entered the program under a different user profile with same results. Cress Mfg is closed for another week so no access to their support. Any ideas or suggestions? What other trials can I do to narrow down the problem? Link to comment Share on other sites More sharing options...
Min Posted July 3, 2017 Report Share Posted July 3, 2017 So, just to make sure I'm following you....first segment is 180/180/0 hold. And it went to 193 from room temp in 20 minutes. And you didn't have any error code. Previous glaze firing went correctly. I'm stumped, maybe try 100/180/0 and see if it still heats up too fast? Really sounds like something wasn't entered right. Was your last ^6 firing with a preprogrammed schedule or did you enter a custom program? Welcome to the forums Link to comment Share on other sites More sharing options...
neilestrick Posted July 3, 2017 Report Share Posted July 3, 2017 1. You may have a stuck relay. Does it stop climbing when you stop the firing? If not, stuck relay, in which case you need to unplug the kiln or kiln the breaker. 2. Depending on the start temp, it may have only needed 20 minutes to get to 180 degrees at a rate of 180/hr. For instance, if the kiln was at 120F, like you had just unloaded it and reloaded it and it was still warm, it would get to 180 in 20 minutes at a rate of 180/hr. 3. 180/hr is a fast climb when shooting for such a low temperature. It can easily overshoot such a low temp, at which point it will just go on to the next step in the program. Try a slower climb, like under 125/hr. Link to comment Share on other sites More sharing options...
Dick White Posted July 3, 2017 Report Share Posted July 3, 2017 I'm not 100% familiar with the exact wiring of this Cress kiln, but an observation about your initial statement. You say the relays (plural) were believed to be working. You unplugged it, plugged it back in, and restarted it. Many kilns have several relays, usually one for each section. You may hear clicking, but that doesn't necessarily mean all are working properly. My guess from the symptoms you describe is that one of the relays is failed in the on position and that section of the kiln just goes to full on. At ambient temperatures, one section full on is enough to cause an uncontrolled temperature increase of the whole kiln. One test of a failed relay in the on position - does the kiln heat up when it is plugged in despite the controller being switched off or in Idle? Link to comment Share on other sites More sharing options...
olpupi Posted July 3, 2017 Author Report Share Posted July 3, 2017 Thanks so much for your suggestions and questions. I ran a program for 120/140/0 hold. It went to 120 and kept on going straight up to 140, with relays cycling on and off, in about 35 minutes and then turned itself off as it should and proceeded to cool down as usual meaning no relays were stuck on. The kiln has always had an obvious buzzing when the relays are on and I don't hear anything when they are cycling off during these trials. So, again, I don't think it's a stuck relay, but I haven't looked inside at the elements during a test. Should have done that. I can go online and see my hourly electric usage for the last bisque and glaze fires. The glaze fire (which was about 3 weeks ago) shows a steady consistent usage over the length of the firing. I just got the smart meter so unfortunately I don't have another glaze firing profile to compare it to. Since I use the factory Cone 5 program I'm not exactly sure if there are set points in the program, but I would think so. The bisque fire, which was about 4 weeks ago, shows varying usage over the hours. That would be expected if it was firing as it should with the various set points. I program the bisque profile in so I know the steps. So I don't see anything wrong with the bisque electrical profile. It seems it just doesn't want to stop at set points. Link to comment Share on other sites More sharing options...
neilestrick Posted July 4, 2017 Report Share Posted July 4, 2017 I ran a program for 120/140/0 hold. It went to 120 and kept on going straight up to 140, with relays cycling on and off, in about 35 minutes and then turned itself off as it should and proceeded to cool down as usual meaning no relays were stuck on. It seems it just doesn't want to stop at set points. Looks like this firing did exactly as it should. Link to comment Share on other sites More sharing options...
olpupi Posted July 5, 2017 Author Report Share Posted July 5, 2017 What am I missing? Shouldn't it have taken an hour to reach 120, and at the end of that hour it would continue up to 140 and shut down. But it did the whole thing in 36 minutes. Link to comment Share on other sites More sharing options...
Dick White Posted July 5, 2017 Report Share Posted July 5, 2017 I am interpreting your "120/140/0" statement to be the numbers you put into the controller for a single segment test firing. That means you programmed it to manage the temperature rise at 120F per hour (i.e., 2 degrees per minute) to 140F and zero hold time (after which it will shut off as there is no further segment). So, if the ambient starting temperature is, let's just say, 75F, that means it has to heat up a total of 65 degrees at a rate of 2 degrees per minute. That should take 32 1/2 minutes. It takes a few minutes for the coils to heat up and begin heating the kiln, so add 3 and your 36 minutes is about right. Link to comment Share on other sites More sharing options...
neilestrick Posted July 5, 2017 Report Share Posted July 5, 2017 I am interpreting your "120/140/0" statement to be the numbers you put into the controller for a single segment test firing. That means you programmed it to manage the temperature rise at 120F per hour (i.e., 2 degrees per minute) to 140F and zero hold time (after which it will shut off as there is no further segment). So, if the ambient starting temperature is, let's just say, 75F, that means it has to heat up a total of 65 degrees at a rate of 2 degrees per minute. That should take 32 1/2 minutes. It takes a few minutes for the coils to heat up and begin heating the kiln, so add 3 and your 36 minutes is about right. Exactly how I interpreted it, too. 120 degrees per hour to 140 degrees, 0 hold time. So it fires up to 140 and shuts off. Perfect. Link to comment Share on other sites More sharing options...
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