JohnS Posted December 22, 2023 Report Share Posted December 22, 2023 Quick question (hopefully) - Using a old duncan electric kiln with kiln sitter I was doing a glaze firing today, wanted to take it slow so I loaded it up at 6.30 and then once an hour I turned it up 1 "hour" (manual kiln with kiln sitter and dial), I did this for the first 4 hours and then whacked it up to the HiFire setting which is what I normally use. However... I went back after 9 hours total and noticed that it was still firing which is unusual as its normally done by then, I realised that I must've went slightly past the HiFire setting as the infinite switches weren't clicking on and off however the kiln was still on. Using an infared thermometer I estimate that it stuck at around 1050c for let's say 6 hours. I've turned the dial back slightly and now the switches are working. My question is - have I just lost all the pots in the kiln? The kiln sitter didn't drop (cone 6), should I switch it off now or let the sitter do it's job? A lot of potentially runny glaze in there and it's the one time I didn't find my witness cone stands so haven't used them! Cheers John Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted December 22, 2023 Report Share Posted December 22, 2023 So 1050c is a long bisque, (accurate IR to 1000c usually in the 500 usd range though ) my experience if you are comfortable with that approximate temp nothing has melted significantly. Generally clay fluxed reactions take place in the last 100c, last 200c should be pretty safe. I would finish the firing the sitter cone at this point should melt appropriate to the heatwork. Quote Link to comment Share on other sites More sharing options...
JohnS Posted December 22, 2023 Author Report Share Posted December 22, 2023 2 minutes ago, Bill Kielb said: So 1050c is a long bisque, (accurate IR to 1000c usually in the 500 usd range though ) my experience if you are comfortable with that approximate temp nothing has melted significantly. Generally clay fluxed reactions take place in the last 100c, last 200c should be pretty safe. I would finish the firing the sitter cone at this point should melt appropriate to the heatwork. Phew! Cheers Bill, put my over active mind at rest. "Generally clay fluxed reactions take place in the last 100c, last 200c should be pretty safe." Thats great info to have. Thanks. Bill Kielb 1 Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted December 22, 2023 Report Share Posted December 22, 2023 @JohnS thanks! I would love to take credit but it is what Orton observed. It has helped me a bunch over the years though. Hopefully pass it along as you need. Quote Link to comment Share on other sites More sharing options...
Babs Posted December 23, 2023 Report Share Posted December 23, 2023 With eye protection can you see any pots through peep hole? Any sheen on the surface? That's a lot of heatwork. Quote Link to comment Share on other sites More sharing options...
JohnS Posted December 30, 2023 Author Report Share Posted December 30, 2023 @Bill Kielb hey Bill, Pots turned out as fine as could be, it didn't reach temperature, the cone 6 pyrometric cone barely bent so while the colours never came out at least they didn't run all over the shelves! I took a look at the kiln today and basically what I'm finding is that the elements kick in as normal up until the 3pm mark, after that they don't cycle on and off. Any ideas what might be the issue there? I took a look at the wiring and everything seems as normal, however I did forget to mention before that when I turned the kiln on for the first time in a while to do that last firing I heard a wee pop and it tripped the circuit, I put it down to dampness in the pottery shed as the kiln fired up on the next try (no wires are melted, elements are all working, nothing visual certainly). Cheers Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted December 30, 2023 Report Share Posted December 30, 2023 Post your model kiln for some ideas on troubleshooting. Timer setting, is this a teacher plus kiln or kiln with timers ……. Quote Link to comment Share on other sites More sharing options...
JohnS Posted December 30, 2023 Author Report Share Posted December 30, 2023 @Bill Kielb Sorry, aye, it's the duncan teacher plus 820 Forgot I wasn't posting on the other duncan kiln thread! One dial that has overglaze, ceramic and hi fire. Ceramic is at 3pm and hi fire is at 1pm which makes me think that it'll never reach the high fire temps and that this was the problem. Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted December 30, 2023 Report Share Posted December 30, 2023 There are several models of this so a picture of the equipment tag may help. These kilns all contain interval timer relays which make troubleshooting a bit more difficult. Here is a place to find your wiring diagram https://corp.paragonweb.com/support/kiln-wiring-diagrams/. The timers are obsolete or replacement is fairly pricey so for those electrically savvy and with a bad timer the common suggestion is change the kiln to operate with good ole infinite switches. This kiln has relays, but they are high voltage relays that use the normally closed set of contacts as well as the normally open in their sequence. End result, a little tougher to troubleshoot and folks sometimes try a 12v (low voltage) relay of today’s standards only o immediately burn up the relay. The infinite switch fix becomes a fairly easy all line voltage fix with available cheap parts. Quote Link to comment Share on other sites More sharing options...
JohnS Posted December 30, 2023 Author Report Share Posted December 30, 2023 @Bill Kielb Here's some photos and a definitely not professional wiring diagram I just did with colouring pencils to show what mine looks like. I've replaced the switches and stuff before so they've both new/used less than a dozen times. There was a wire popped out from the section where the power comes in, I'm positive that came out when I took the casing off and the only logical place it came from, I think is the L1 position. It's worth noting that my wiring seems different from the duncan wiring diagram slightly (no cable in the P slot on their diagram), however they don't actually have a diagram for the EA820 6, they've got 2 for the 820 8 instead... Quote Link to comment Share on other sites More sharing options...
neilestrick Posted December 30, 2023 Report Share Posted December 30, 2023 1 hour ago, JohnS said: Ceramic is at 3pm and hi fire is at 1pm which makes me think that it'll never reach the high fire temps and that this was the problem. Yep. If you put it on Ceramic it's basically just staying on medium. You need to set it to hi fire. Quote Link to comment Share on other sites More sharing options...
JohnS Posted December 30, 2023 Author Report Share Posted December 30, 2023 @neilestrick Hi Neil, yeah, that's not the problem here. At risk of repeating everything again basically the kilns elements aren't cycling when it's turned higher than the ceramic setting. Quote Link to comment Share on other sites More sharing options...
neilestrick Posted December 30, 2023 Report Share Posted December 30, 2023 9 minutes ago, JohnS said: @neilestrick Hi Neil, yeah, that's not the problem here. At risk of repeating everything again basically the kilns elements aren't cycling when it's turned higher than the ceramic setting. On hi they probably won't cycle, they'll just stay on. If they're staying on but it's not hitting temperature, then the elements are probably worn. Are you sure the switches were installed properly? If I remember correctly they are installed upside down in these kilns. The best solution to making these kilns work well is to simply gut them and replace all the switches with infinite switches wired directly to the elements and sitter, no relays or timers. Quote Link to comment Share on other sites More sharing options...
JohnS Posted December 30, 2023 Author Report Share Posted December 30, 2023 Ah, it's possible that it never cycled on amd off in the past and I just never noticed. I'm sure I installed the switches correctly last time, it certainly fired correctly last time I used it. I'll give it another bisque and glaze firing this week and this time remember the witness cones... Cheers. Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted December 30, 2023 Report Share Posted December 30, 2023 This is a pricey fix to restore depending on parts. I would double check element resistance first. Since this tripped the breaker, something likely arced and depending on what, could be expensive. First step in my mind, make sure the elements are good. What resistance do they measure? Quote Link to comment Share on other sites More sharing options...
JohnS Posted December 30, 2023 Author Report Share Posted December 30, 2023 Cool, will check. Not sure on the resistance part yet, need to measure. I'mcone step away from ordering a new kiln anyway so if there's any drama at all then it's getting used as a bisque or raku kiln in future! neilestrick 1 Quote Link to comment Share on other sites More sharing options...
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