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My weird kiln won't reach temp


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#1 Mesi

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Posted 26 April 2013 - 08:48 AM

Now, I know there are a number of troubleshooting threads on here about kilns not reaching temperature, but my problem is a little more complicated. See, I have an old Nova 18 kiln. Its a ceramic fiber kiln where the elements are embedded in the walls.

I'm trying to fire to cone 6, and have successfully done so many times before, but this time (probably because I have a show the first week in May, and hey, what could stress me out more?) it will. not. reach. temp. And it is SO CLOSE. The kiln color and look of the pieces leads me to believe its hovering around cone 5. Maybe even ^5.5. Its very close but my touchier glazes aren't there yet. I've tried 3 times to get it to temp and every time it's timing out before hitting temp. And I'm being more than generous with the time. I had some suspicions that something might be going last time I fired. I took the cone out of the sitter and it wasn't quite to 90 degrees. Bent certainly, but a little under where it usually is. Had I been smart I would have put witness cone packs on all my shelves and checked it out further, but I didn't. Live and learn.

The specs:

-Nova 18 model KL-21830 Series 218
-6120 Watts, 240 V, 1 phase

-Interior size is about 18" deep by 18" in diameter

-Kiln sitter model LT-3K

Breakers are fine, plug is fine, I know the electrical going to it is good, I had a master electrician install it specifically for this kiln. Fires to lower temps within a normal time range, the last firing had the cone barely under-fired looking. Generally a glaze fire takes me about 7 hours, 1 on low, 1 on medium, then I turn it up to high. I've reliably used this glaze firing schedule on all my previous firings. This time I did the same, one hour on low, 1 on medium, turn to high. I checked it at the end of the time, and it had timed out but the latch on my sitter had not dropped. I immediately reset the timer for 5 more hours (figuring I would just keep checking on it) and restarted it. Again, it timed out and didn't reach temp. I started it AGAIN, and it just hovered there, looking like it was about cone 5. 4.5 more hours and I just turned it off. I let it cool yesterday evening and last night and peered into it this morning, and things just look kinda under fired. It was still too hot to open up and check the cone. I'll do that tonight when I get home from work. I'll also turn it on high with the lid open and see if I can see the elements glowing through the walls. It's really hard to see though, as the ceramic fiber all just glows when heated up.

Something I did notice last night was the lack of noise from the sitter. Generally it hums on and off, punctuated every once in a while by little popping noises. Now, I'm not sure if this is normal sitter behavior, but it's normal for mine. I don't know much about the nuts n bolts of kiln controls, so I'm at a little but of a loss here, but do you think there's any chance that it could be something in there that's going?

#2 neilestrick

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Posted 26 April 2013 - 10:17 AM

The only noise the sitter should be making is from the timer. It hums and makes little rattling noises. This is hard to diagnose over the internet, but you've either got a bad connection somewhere so that one or more elements are not getting power, or you've got a burned out element. You'll need to get into the control box with a meter and start testing things. If you're not comfortable doing it yourself, get a kiln tech in to do it. If you need a new element, I have no idea how to change an element in that type of kiln. Do you have to buy a whole new fiber wall module with the elements already embedded?
Neil Estrick
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www.neilestrickgallery.com

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#3 Mesi

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Posted 26 April 2013 - 10:36 AM

The only noise the sitter should be making is from the timer. It hums and makes little rattling noises. This is hard to diagnose over the internet, but you've either got a bad connection somewhere so that one or more elements are not getting power, or you've got a burned out element. You'll need to get into the control box with a meter and start testing things. If you're not comfortable doing it yourself, get a kiln tech in to do it. If you need a new element, I have no idea how to change an element in that type of kiln. Do you have to buy a whole new fiber wall module with the elements already embedded?


My husband is electrically savvy. I'll pop the front off the control box tonight and have him check the connections with a meter. I'm praying this isn't a burned out element, because the kiln is just dead if one of the elements goes. There's no way to extract them from the fiber, they look molded in. It's probably 40 years old and this style wasn't produced for very long, probably BECAUSE of the inevitable element death. Somewhere on Clayart someone had a picture of one, but I can't find it now to post.

#4 Arnold Howard

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Posted 26 April 2013 - 01:38 PM

Now, I know there are a number of troubleshooting threads on here about kilns not reaching temperature, but my problem is a little more complicated. See, I have an old Nova 18 kiln. Its a ceramic fiber kiln where the elements are embedded in the walls.

I'm trying to fire to cone 6, and have successfully done so many times before, but this time (probably because I have a show the first week in May, and hey, what could stress me out more?) it will. not. reach. temp. And it is SO CLOSE.


I think your elements are starting to age. If I were you, I would fire the kiln only to lower temperatures.

Sincerely,

Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com

#5 neilestrick

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Posted 26 April 2013 - 02:37 PM

It's probably 40 years old


If it's that old you're probably out of luck.
Neil Estrick
Kiln Repair Tech
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Owner, Neil Estrick Gallery, LLC
www.neilestrickgallery.com

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#6 Mesi

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Posted 26 April 2013 - 03:20 PM


It's probably 40 years old


If it's that old you're probably out of luck.


Hey, a girl has to dream?Posted Image I just need this baby to stay with me a little bit longer until I can afford a new one. lol

#7 annekat

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Posted 14 May 2013 - 02:42 PM


Now, I know there are a number of troubleshooting threads on here about kilns not reaching temperature, but my problem is a little more complicated. See, I have an old Nova 18 kiln. Its a ceramic fiber kiln where the elements are embedded in the walls.

I'm trying to fire to cone 6, and have successfully done so many times before, but this time (probably because I have a show the first week in May, and hey, what could stress me out more?) it will. not. reach. temp. And it is SO CLOSE.


I think your elements are starting to age. If I were you, I would fire the kiln only to lower temperatures.

Sincerely,

Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com


I bought an older used Skutt that looked in perfect condition. But the elements all needed replacing, as it would reach bisque temp just fine but not Cone 6. On inspection, they all had a strange wrinkled appearance on their surfaces. Since it is a Skutt, this wasn't a problem, except for the unexpected expense. Now these elements are at least 10 years old and still working, though they have noticeably slowed down. I can still fire to ^6, but I can see that wrinkly texture on the elements. Just my experience; of course I should have checked the resistance of the elements with an OHM meter before buying the kiln, but I'm happy with the use I've gotten out of it and the elements I bought. I'm sorry your kiln is a weird brand and this probably won't be an option. But enjoy its use at lower temperatures, anyway.
Anne

#8 Mesi

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Posted 15 May 2013 - 10:34 AM

[/quote]
I bought an older used Skutt that looked in perfect condition. But the elements all needed replacing, as it would reach bisque temp just fine but not Cone 6. On inspection, they all had a strange wrinkled appearance on their surfaces. Since it is a Skutt, this wasn't a problem, except for the unexpected expense. Now these elements are at least 10 years old and still working, though they have noticeably slowed down. I can still fire to ^6, but I can see that wrinkly texture on the elements. Just my experience; of course I should have checked the resistance of the elements with an OHM meter before buying the kiln, but I'm happy with the use I've gotten out of it and the elements I bought. I'm sorry your kiln is a weird brand and this probably won't be an option. But enjoy its use at lower temperatures, anyway.
[/quote]

Yeah, the elements are totally embedded within ceramic fiber. There's no way to get to them. I've resigned myself to getting a new kiln and just using this one for bisque and other low fire.

#9 annekat

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Posted 15 May 2013 - 09:59 PM

[quote name='vervain' date='15 May 2013 - 08:34 AM' timestamp='1368632096' post='34897']
[/quote]
I bought an older used Skutt that looked in perfect condition. But the elements all needed replacing, as it would reach bisque temp just fine but not Cone 6. On inspection, they all had a strange wrinkled appearance on their surfaces. Since it is a Skutt, this wasn't a problem, except for the unexpected expense. Now these elements are at least 10 years old and still working, though they have noticeably slowed down. I can still fire to ^6, but I can see that wrinkly texture on the elements. Just my experience; of course I should have checked the resistance of the elements with an OHM meter before buying the kiln, but I'm happy with the use I've gotten out of it and the elements I bought. I'm sorry your kiln is a weird brand and this probably won't be an option. But enjoy its use at lower temperatures, anyway.
[/quote]

Yeah, the elements are totally embedded within ceramic fiber. There's no way to get to them. I've resigned myself to getting a new kiln and just using this one for bisque and other low fire.
[/quote]
If the elements ever become totally shot, so you can't fire it at all, it sounds like it would make a nice little raku kiln! Just make a hole in it for a burner and create a flue in the lid with a piece of shelf for a damper.


Anne

#10 Mesi

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Posted 16 May 2013 - 09:28 AM

If the elements ever become totally shot, so you can't fire it at all, it sounds like it would make a nice little raku kiln! Just make a hole in it for a burner and create a flue in the lid with a piece of shelf for a damper.



OooOOohhh. Valid. I like that idea. It's a decent shell, the metal and the fiber are in great shape, its just old and the elements are slowly going. I think I'll definitely look into a raku kiln conversion once it's gone for good. I've never done raku, but I want to (my mother did it a lot back in the 70's).

#11 Woody Sheep

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Posted 16 May 2013 - 01:29 PM

Hmmm....I just replaced the elements in my old Cress. It had the same symptoms as yours. Mine has three banks of elements. When I checked them...easy to do, Disconnect each element, then just check em with an Ohm meter ... I found the bottom one burned out. So the kiln was getting hot from the other two but it needed all three to reach final temp.

From experience, check the manufacturers web site, somewhere buried in there should be specs on what each bank of elements should read on the Ohm scale. Mine was 41 Ohms for the Top and Middle, and only 36 for the lower...unless one is broken, in which case your reading will be 1. You need to know these reading to make a comparison.

When you do get the new elements, there will come with a full instruction sheet on how to replace them. It really isn't that difficult.... unless in your case where you can't access them....If you try, be careful these old kiln used Asbestos as insulation.
Sorry i couldn't be more help.

PS The relays make a very loud popping noise when they turn the electricity on and off to the elements. Its really scary at night when you can see the relays flash as the electricity arcs between them.

#12 Mesi

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Posted 16 May 2013 - 03:17 PM

Hmmm....I just replaced the elements in my old Cress. It had the same symptoms as yours. Mine has three banks of elements. When I checked them...easy to do, Disconnect each element, then just check em with an Ohm meter ... I found the bottom one burned out. So the kiln was getting hot from the other two but it needed all three to reach final temp.

From experience, check the manufacturers web site, somewhere buried in there should be specs on what each bank of elements should read on the Ohm scale. Mine was 41 Ohms for the Top and Middle, and only 36 for the lower...unless one is broken, in which case your reading will be 1. You need to know these reading to make a comparison.

When you do get the new elements, there will come with a full instruction sheet on how to replace them. It really isn't that difficult.... unless in your case where you can't access them....If you try, be careful these old kiln used Asbestos as insulation.
Sorry i couldn't be more help.

PS The relays make a very loud popping noise when they turn the electricity on and off to the elements. Its really scary at night when you can see the relays flash as the electricity arcs between them.



As I said above, you can't get to the elements in my kiln. They're encased totally. Kiln is a Nova18, a brand that has been discontinued since the early 80s as far as I can tell. No manufacturer to contact.

#13 OffCenter

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Posted 16 May 2013 - 04:08 PM

As I said above, you can't get to the elements in my kiln. They're encased totally. Kiln is a Nova18, a brand that has been discontinued since the early 80s as far as I can tell. No manufacturer to contact.


Nova Kilns was bought by Thermolyne Corp. They make lab kilns/ovens and other scientific heating products now and in some products the elements are covered by ceramic fiber like your kiln. You replace the elements to those products not from the inside but from the outside by removing the plates that cover the kiln. Not having seen a pic of your kiln I have no idea if it is worth the effort but surely there is a way to replace the elements. If any supply house has elements for it, it would be Euclids.com. They may also know how to replace the elements in your kiln. May come to nothing, but may be worth a shot.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#14 ShAwNa15

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Posted 18 August 2013 - 11:12 AM

Hello, im sorry to say that I can't help you. I've recently bought the same kiln off a ceramist and the owners manual was ruined due to flooding she had had a few years back. I was wondering if you would please send me a scan of yours as i have been unable to find one to download online. Thank you very much :)

#15 Arnold Howard

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Posted 19 August 2013 - 10:26 AM

Hello, im sorry to say that I can't help you. I've recently bought the same kiln off a ceramist and the owners manual was ruined due to flooding she had had a few years back. I was wondering if you would please send me a scan of yours as i have been unable to find one to download online. Thank you very much :)

Duncan bought rights to the Nova kiln during the 1970s. All the Duncan kiln manuals can be downloaded from the Paragon website. (We list the Duncan manuals because we contracted with Duncan to sell their kiln parts after they discontinued kiln production in 1997.) Here is the link to the manual for the Duncan EA-092 The Crafter-Plus and the EA-122 The Artist-Plus ceramic fiber kilns. I believe these models were originally Nova kilns.

 

http://www.paragonwe...nfo.cfm?CID=171

 

Sincerely,Arnold Howard

Paragon Industries, L.P.,

Mesquite, Texas USA

ahoward@paragonweb.com / www.paragonweb.com






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