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Kiln Firing Slowly


RogueArtist

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Hello all,

 

So I have a small manual electric kiln. It's 30-40 years old (free from someone who was going to toss it). It's been running ok, but recently I've been having problems with excessively long firing times.

 

Yesterday I started the firing at 6:30 in the morning and wasn't finished until 2:00 am! 19 hours! I'm firing to cone 5.

 

I just replaced the elements last month, the wiring is all new, and I replaced the switches. All the wiring/electrical has been double and triple checked. I don't know what else could be wrong with it. It is coming to temperature just â€‹very slowly.

 

The kiln is an L&L J18 manual 16"x18".

 

Advice anyone?

Thanks in advance!
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The kiln had been slowing down until one day it wouldn't come up to temperature. That's when I replaced the elements and it worked fine for a few firings. However after 4 firings the top element burned out. It glowed brightly at one spot and then melted itself in two along the double-stranded section that passes through the ceramic holder out of the kiln. I don't know why that happened, there was nothing in the holder, the wiring was triple checked, and it wasn't touching any other wire/shorting out.

 

Anyway, I replaced the top element, then did an empty firing to break it in. That firing went as I expected (faster because the kiln was empty, all the elements were glowing and the switches were behaving normally). This past firing (the 19 hour one) is the first 'real' firing after replacing the top element.

 

I checked the olms for each element and they were within the right range, I also checked the electricity at the plug and we are getting 140 (and it's a 140 kiln) so that should be good. I guess there's not a way to see how much current it's actually drawing without trying to fire it again?

 

Thanks for the replies!

 

 

 

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I assume you mean 240 volts, not 140? If you're reading 140 then you've got a problem.

 

It's possible a switch went bad during the firing. You can check the voltage and amperage at the elements with the power flowing, but it's a little tricky to do it safely on a manual kiln if the control boxes aren't hinged. Be careful. Another way to check the switches is to do an ohm test through the power cord. Unplug the kiln, put the probes on the two leads of the plug, turn on the sitter, and check the ohms at each setting on the switch (lo,med,high).

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Neilstrick - oops! I meant 240 - big difference! I have to go try your suggestions. When I check the ohms through the power cord should there be a difference at different switch settings?

 

DirtRoad, the kiln is rated for cone 10 but I have never fired it that high. My usual schedule is 04 bisque and 5 glaze.

 

Thanks everybody!

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