Paora Posted January 12, 2023 Report Share Posted January 12, 2023 Hi all, I'm a wheel potter in New Zealand and i bought this Duncan pro plus kiln recently for bisquing, that gets too hot too quickly no matter where I position the 2 temperature dials. Does anyone by chance know weather, I need new infinity switches or possibly new relays? Any help would be greatly appreciated thanks so much. Paora Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 12, 2023 Report Share Posted January 12, 2023 (edited) 450c per hour is definitely rocket speed. Something easy to try: With the top switch off (12:00) and the bottom switch turned just on or pointing about 11:00 (just a slight turn counter clockwise) how fast does this thing fire to 500 c? Speed is often is a common issue with this style kiln and is often the result of the timing relays. It can be operation though as the temperature controls operate a bit backwards from what folks are used to. Here is a thread that may help https://community.ceramicartsdaily.org/topic/17923-help-with-using-a-duncan-automatic-teacher-plus-kiln/ as well. Post a picture of your equipment tag showing model, etc…. The problem with this, the timing relays are very expensive and at this point really hard to come by so diagnosing is difficult but usually necessary as opposed to just swapping parts. Edited January 12, 2023 by Bill Kielb Quote Link to comment Share on other sites More sharing options...
Jeff Longtin Posted January 12, 2023 Report Share Posted January 12, 2023 A curious question: is the kiln sitting on hard brick? (Can you easily scratch the surface?) I've never seen the use of hard brick in an electric kiln. I wonder if that contributes to the problem? Quote Link to comment Share on other sites More sharing options...
neilestrick Posted January 12, 2023 Report Share Posted January 12, 2023 The timer switches at the bottom of the control box are supposed to hold the temp on low for 2 hours before it ramps up, so there is likely a problem in one or both of those switches. Replacements may or may not be available. I worked on a similar Duncan last week where we tore out all the relays and timer switches, and wired the elements directly to infinite switches. The original setup had two switches, but with 3 element groupings I had to add a third switch to the panel. It's now a fully manual kiln, but the owner has a lot more control over firing speed, and can candle overnight with just the bottom ring on low. Doing this is a good option for keeping these kilns running and making them more user friendly. You just have to make sure you don't overload the switches since infinite switches are only rated for 15 amps, however these kilns usually max out at 15 amps per element grouping. Bill Kielb 1 Quote Link to comment Share on other sites More sharing options...
Paora Posted January 13, 2023 Author Report Share Posted January 13, 2023 On 1/13/2023 at 2:03 AM, Bill Kielb said: 450c per hour is definitely rocket speed. Something easy to try: With the top switch off (12:00) and the bottom switch turned just on or pointing about 11:00 (just a slight turn counter clockwise) how fast does this thing fire to 500 c? Speed is often is a common issue with this style kiln and is often the result of the timing relays. It can be operation though as the temperature controls operate a bit backwards from what folks are used to. Here is a thread that may help https://community.ceramicartsdaily.org/topic/17923-help-with-using-a-duncan-automatic-teacher-plus-kiln/ as well. Post a picture of your equipment tag showing model, etc…. The problem with this, the timing relays are very expensive and at this point really hard to come by so diagnosing is difficult but usually necessary as opposed to just swapping parts. Hey thanks Bill I appreciate the help. I've gone through the link in your reply but haven't found anything particular that pinpoints what the issue might be unfortunately. I tried following your advice which produced a better (gradual) rise in temperature from around 300 degree's Celsius up to 500. However it's still rising too fast in the beginning. Any ideas? Quote Link to comment Share on other sites More sharing options...
Paora Posted January 13, 2023 Author Report Share Posted January 13, 2023 On 1/13/2023 at 7:07 AM, Jeff Longtin said: A curious question: is the kiln sitting on hard brick? (Can you easily scratch the surface?) I've never seen the use of hard brick in an electric kiln. I wonder if that contributes to the problem? Hi Jeff, yes my set-up is unusual lol. The floor of the kiln was damaged and needed replacing and I had some refractory bricks spare. The kiln sits on a red wooden trolley that allows me to roll the kiln away from the house but I was worried about the wood catching alight. In between the bricks and the trolley is aerated concrete blocks which were being thrown out. It's a bit messy, but to find a steel trolley that fitted the job I probably would have to sell a lung to afford it so I put these waste items to use. I've since placed some fibre into the bottom which probably negates the bricks lol, but "in for a penny, in for a pound" as they say. Oh and if you're wondering about the epic length of the probe is because it's usually used on my gas kiln that has 6" walls. Cheers Quote Link to comment Share on other sites More sharing options...
Paora Posted January 13, 2023 Author Report Share Posted January 13, 2023 On 1/13/2023 at 8:45 AM, neilestrick said: The timer switches at the bottom of the control box are supposed to hold the temp on low for 2 hours before it ramps up, so there is likely a problem in one or both of those switches. Replacements may or may not be available. I worked on a similar Duncan last week where we tore out all the relays and timer switches, and wired the elements directly to infinite switches. The original setup had two switches, but with 3 element groupings I had to add a third switch to the panel. It's now a fully manual kiln, but the owner has a lot more control over firing speed, and can candle overnight with just the bottom ring on low. Doing this is a good option for keeping these kilns running and making them more user friendly. You just have to make sure you don't overload the switches since infinite switches are only rated for 15 amps, however these kilns usually max out at 15 amps per element grouping. Thanks Neil, you sound like a handy guy to know, it's a shame you don't live around the corner. So I was hoping (naively) that someone on this forum would identify that initial fast acceleration of temperature means that this particular relay or component needs replacing and then I would buy it online and get a local electrician to install it. Or am I wasting my time trying to revive this relic do you reckon? Cheers Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 14, 2023 Report Share Posted January 14, 2023 (edited) 23 hours ago, Paora said: I tried following your advice which produced a better (gradual) rise in temperature from around 300 degree's Celsius up to 500. However it's still rising too fast in the beginning. Any ideas? Actually better than I thought it would be. So propping the lid is another common way to slow things to dry them out, just an inch or two ( let’s say 2-5cm) to go slow through 100c. Just from the slope of the line, it looks like a fairly normal climb rate. So a loaded kiln start with top switch off and bottom minimally on (11:00 O’clock) prop lid for first hour, then close lid, turn top switch just on, say 11:00 o’clock after three hours. You might be able to make useable. Neil is right though, those relays IMO are not worth it and I just convert these to all infinite switch operation. Often can re- use the top and bottom switch and get by installing just one additional infinite switch though. This does require you to be handy though. BTW - this is a fairly clear diagram I have that MAY apply to your kiln? Do you have a rocker switch somewhere for low, Manual, Auto? If you have this switch, then what position have you used this in? If this diagram fits your kiln, then you can place the center elements on the upper relay and jump out the timers fairly easy, in a pinch. Your kiln would only operate manually with the top and bottom infinite controls at that point. Just reviewing your picture, the center elements are on all the time your kiln sitter is, moving the center elements to operate from the top element relay will solve this and place it under your control. The timers should also be removed (simple one wire removal) else they may cause more confusion in operation. So fairly easy to try by relocating two wires and disconnecting one timer jumper I believe. Edited January 14, 2023 by Bill Kielb Quote Link to comment Share on other sites More sharing options...
Babs Posted January 14, 2023 Report Share Posted January 14, 2023 Wierd kiln with sitter at the bottom which ina top loader can run cooler. And overkill length of pyrometer, looks like that has come from a large gas kiln set up. If all else doesnt slow it down, nothing stopping you leaving the lid propped open and shutting it gradually, I noiced you biswuing to just over 900, or are you going on cones in sitter and at spyhole? Do you plug those bung holes after a time? How full do you stack your kiln? Quote Link to comment Share on other sites More sharing options...
neilestrick Posted January 14, 2023 Report Share Posted January 14, 2023 19 hours ago, Bill Kielb said: Just reviewing your picture, the center elements are on all the time your kiln sitter is, moving the center elements to operate from the bottom element relay will solve this and place it under your control. The timers should also be removed (simple one wire removal) else they may cause more confusion in operation. So fairly easy to try by relocating two wires and disconnecting one timer jumper I believe. Top- 15 amps Middle- 9.5 amps Bottom- 21.8 amps If you put the bottom and middle on the same relay you're going to be at 31.3 amps. I don't see on the diagram where it says, but chances are that's only a 25 or 30 amp relay. What you could do is connect the middle elements directly to the infinite switch along with the control side of the top relay. That switch would then only be handling the 9.5 amps of the middles section and the very little power to switch the relay for the top section. Plus that way the bottom section is on its own for candling/preheat. Ditch the timers and the middle control relay. L1 and L2 of both switches should connect directly to the Sitter, as well as the power inputs to both relays. Someone please confirm as I'm not drawing this out as I write it! Bill Kielb 1 Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 14, 2023 Report Share Posted January 14, 2023 (edited) 20 minutes ago, neilestrick said: Bottom- 21.8 amps Good catch - bad math in my note! Neil’s right, top and middle combined fits the relay better at 25 amp contacts I believe. Or just add an infinite switch for middle elements and still disconnect the timer connections to the sitter. The middle relay is a normally closed so ditch the timers I think is easy or ditch the relay but jump out ALL the L2 connections to it, as necessary as if the relay is closed would be my thought. Fixed the drawing above too. Edited January 14, 2023 by Bill Kielb Quote Link to comment Share on other sites More sharing options...
Paora Posted January 15, 2023 Author Report Share Posted January 15, 2023 On 1/14/2023 at 1:28 PM, Bill Kielb said: Actually better than I thought it would be. So propping the lid is another common way to slow things to dry them out, just an inch or two ( let’s say 2-5cm) to go slow through 100c. Just from the slope of the line, it looks like a fairly normal climb rate. So a loaded kiln start with top switch off and bottom minimally on (11:00 O’clock) prop lid for first hour, then close lid, turn top switch just on, say 11:00 o’clock after three hours. You might be able to make useable. Neil is right though, those relays IMO are not worth it and I just convert these to all infinite switch operation. Often can re- use the top and bottom switch and get by installing just one additional infinite switch though. This does require you to be handy though. BTW - this is a fairly clear diagram I have that MAY apply to your kiln? Do you have a rocker switch somewhere for low, Manual, Auto? If you have this switch, then what position have you used this in? If this diagram fits your kiln, then you can place the center elements on the upper relay and jump out the timers fairly easy, in a pinch. Your kiln would only operate manually with the top and bottom infinite controls at that point. Just reviewing your picture, the center elements are on all the time your kiln sitter is, moving the center elements to operate from the top element relay will solve this and place it under your control. The timers should also be removed (simple one wire removal) else they may cause more confusion in operation. So fairly easy to try by relocating two wires and disconnecting one timer jumper I believe. Hey this greatly appreciated Bill however I don't think your picture is the same as my kiln, mine doesn't have a rocker switch. You and Neil are very knowledgeable however I have no experience with electrical issues so I'm going to show your helpful comments to a sparky over here and see if he can follow your awesome instructions. Thanks again. Paora Quote Link to comment Share on other sites More sharing options...
Paora Posted January 15, 2023 Author Report Share Posted January 15, 2023 11 hours ago, neilestrick said: Top- 15 amps Middle- 9.5 amps Bottom- 21.8 amps If you put the bottom and middle on the same relay you're going to be at 31.3 amps. I don't see on the diagram where it says, but chances are that's only a 25 or 30 amp relay. What you could do is connect the middle elements directly to the infinite switch along with the control side of the top relay. That switch would then only be handling the 9.5 amps of the middles section and the very little power to switch the relay for the top section. Plus that way the bottom section is on its own for candling/preheat. Ditch the timers and the middle control relay. L1 and L2 of both switches should connect directly to the Sitter, as well as the power inputs to both relays. Someone please confirm as I'm not drawing this out as I write it! Hey Neil thanks so much for your helpful comments but I'm going to have to tap out, I have no experience with electrical issues. But I'm going to show yours and Bills info to a local sparky and see if he can work it out. Thanks so much for your help, I owe you both a beer. Paora Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 15, 2023 Report Share Posted January 15, 2023 4 hours ago, Paora said: Hey this greatly appreciated Bill however I don't think your picture is the same as my kiln, mine doesn't have a rocker switch. You and Neil are very knowledgeable however I have no experience with electrical issues so I'm going to show your helpful comments to a sparky over here and see if he can follow your awesome instructions. Thanks again. No worries, your pictures match up really well as this kiln without the switch. Definitely need to be handy with wiring so wise to wait for your friend. If he looks at it and agrees I am pretty sure from your pictures and the drawing it will be easy to show him the issue and he can match the drawing and function. At least you will have a future option available. Quote Link to comment Share on other sites More sharing options...
Paora Posted January 15, 2023 Author Report Share Posted January 15, 2023 Sounds like a plan. Hey are these infinity switches commonly available at an electrical wholesalers for purposes other than using in a kiln or would I need to buy 2 from paragon specifically? Thanks again Bill Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 15, 2023 Report Share Posted January 15, 2023 They are very available. Match the loading voltage and amperage though. Currently yours drive relays so not much load but they are used commonly for heaters, stoves etc…. Universal models available 3600 W I believe or 15 Amos at 240 v. Universal come with shaft adapters, can be directional and include push to turn so for an exact match, get the replacement Paragon suggests. Otherwise it takes a bit of thinking but very doable for many. Quote Link to comment Share on other sites More sharing options...
neilestrick Posted January 15, 2023 Report Share Posted January 15, 2023 They'll be a lot cheaper if you don't get them from Paragon. Check Amazon, or just Google search. Quote Link to comment Share on other sites More sharing options...
Paora Posted January 15, 2023 Author Report Share Posted January 15, 2023 Awesome thanks again Neil Quote Link to comment Share on other sites More sharing options...
Paora Posted January 15, 2023 Author Report Share Posted January 15, 2023 6 hours ago, Bill Kielb said: They are very available. Match the loading voltage and amperage though. Currently yours drive relays so not much load but they are used commonly for heaters, stoves etc…. Universal models available 3600 W I believe or 15 Amos at 240 v. Universal come with shaft adapters, can be directional and include push to turn so for an exact match, get the replacement Paragon suggests. Otherwise it takes a bit of thinking but very doable for many. Excellent advice Bill, thanks so much Quote Link to comment Share on other sites More sharing options...
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