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Linh

Kiln not reaching temperature

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I just bought a used Cress kiln that doesn’t fire to temperature.  Did a glaze fire today. 1 hr low , 2 hr medium, 6 hrs high. From noon to nine. Oven is not reaching cone 6. Stand up cones have not bent, sitter doesn’t shut off.  Turned oven off with breaker again. I guess it’s ok, as long as the pots look ok?

i think it fires to cone 04 fine. Meaning, the sitter shut off with a cone o4.  And it fired to cone 6 once when I was testing the kiln and sitter when it was empty. I’m hoping to buy a standalone controller, but that probably won’t change how hot the kiln goes....but should I just accept that my kiln just won’t fire to temperature. What else can I do? It’s a kiln that’s only supposed to fire to cone 6. I actually had it fire for 16 hrs by accident, not knowing that it wouldn’t reach temperature. The pots seem to look fine after firing. Should I be worried about anything. 

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Hi Linh,

When you don't fire to temperature, the pots may show issues down the line, even if they look okay now. It may be just fine for decorative items, but if you are making dinnerware, this is not a good idea. Besides that, you should be able to get to temperature. 

The first thing I would check is that you have the correct voltage and phase. Look at the electrical specs on the side of the controller box. Is the kiln wired to run on 208 or 240 volts? If it is a 240v kiln running on a 208v service, you will not be able to get to temperature. The second thing I would do, if the voltage is correct, is to run a full power test to make sure all of the elements are working. Turn the kiln on high for 20 minutes and then check to see if all of the elements glow. If you see some are not running, then you may have burned out element(s). They would not glow and would most likely show signs of damage. If you see a section of the kiln is not working with no fault in the elements, it could be a simple matter of replacing a relay.

This would be a good starting point on troubleshooting your issue.

 

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Even if all the elements glow, they could be worn and not running as hot as they should. The only way to know for sure is to test the element resistance with a multi-meter. That said, if they all glow but it won't get to temp, then that's really the only thing that could be wrong, assuming your voltage is correct.

If I'm understanding what you're saying, the kiln is only rated to cone 6? The problem with firing a cone 6 kiln to cone 6 is that it's going to have to work really hard to get to temp every time, and as soon as the elements wear even a little bit, it won't reach temp. If the kiln was rated to cone 10, the elements could wear quite a bit before they became a problem. So with your kiln, you're going to be replacing elements a lot more often. It's not an ideal situation. Technically, your kiln should be used for low fire work.

As FrankieGirl said, you don't want under-fired pots. Clay that hasn't vitrified will weep, and glazes that haven't fully matured may not be food safe or durable.

I would talk to Cress and see if they make a set of elements for that kiln that will go to cone 10. The only problem will be that it will pull more amperage, which means it will need a different breaker and service wiring. How big is the kiln? Can you post a picture of it, and the serial plate with the electrical info on it?

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On 9/23/2018 at 5:00 AM, Frankiegirl said:

Hi Linh,

When you don't fire to temperature, the pots may show issues down the line, even if they look okay now. It may be just fine for decorative items, but if you are making dinnerware, this is not a good idea. Besides that, you should be able to get to temperature. 

The first thing I would check is that you have the correct voltage and phase. Look at the electrical specs on the side of the controller box. Is the kiln wired to run on 208 or 240 volts? If it is a 240v kiln running on a 208v service, you will not be able to get to temperature. The second thing I would do, if the voltage is correct, is to run a full power test to make sure all of the elements are working. Turn the kiln on high for 20 minutes and then check to see if all of the elements glow. If you see some are not running, then you may have burned out element(s). They would not glow and would most likely show signs of damage. If you see a section of the kiln is not working with no fault in the elements, it could be a simple matter of replacing a relay.

This would be a good starting point on troubleshooting your issue.

 

That’s really great advice!! I will turn it on high today...

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8 hours ago, Babs said:

Yeh how big is the kiln?

9 hours not a lot for some kilns.

Put some lines of cones around kiln

That way you may find out what cone it's getting to.

 

Perfect! Thanks!

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Thank you so much for the feed back.  It's been really helpful!

Though I might still have the problems you mentioned. 

I just learned that I'm only getting 208v and my kiln is 240v.   I have it hooked up at my brother's warehouse, but learned that commercial buildings are only wired for 208v.  That is something I cannot change.  So the kiln is working at 85.6% capacity.   The question I have now is weather or not I can just have the kiln heat longer for it to reach temperature?  What is the math on that?  Mind 

The other question I have, is that has anyone been able to convert a 240 v plug into 2 x120 plugs?  I saw it done online.  But is this a safe thing to do?

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27 minutes ago, Linh said:

Thank you so much for the feed back.  It's been really helpful!

Though I might still have the problems you mentioned. 

I just learned that I'm only getting 208v and my kiln is 240v.   I have it hooked up at my brother's warehouse, but learned that commercial buildings are only wired for 208v.  That is something I cannot change.  So the kiln is working at 85.6% capacity.   The question I have now is weather or not I can just have the kiln heat longer for it to reach temperature?  What is the math on that?  Mind 

The other question I have, is that has anyone been able to convert a 240 v plug into 2 x120 plugs?  I saw it done online.  But is this a safe thing to do?

Usually 120v outlets are chained and on a light amperage breaker.  So you'd probably end up just throwing the breaker every time it fired up (good result), or having the wires catch on fire (worst result).  

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So I just learned that I need to change the elements in the kiln, so that it can fire properly with 208v.  which will cost $400.

 

The question I have now, is that whether or not I should keep the kiln as is, and fire really low fire stuff: Cone 4.  

What is your experience with low fire clays and glazes?

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3 minutes ago, Linh said:

So I just learned that I need to change the elements in the kiln, so that it can fire properly with 208v.  which will cost $400.

 

The question I have now, is that whether or not I should keep the kiln as is, and fire really low fire stuff: Cone 4.  

What is your experience with low fire clays and glazes?

Why not both?  Use your kiln at a lower cone until it needs new elements?

 

Btw here is a good article on kiln power:

http://www.bigceramicstore.com/info/ceramics/kiln_power.html

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2 hours ago, Linh said:

So I just learned that I need to change the elements in the kiln, so that it can fire properly with 208v.  which will cost $400.

 

The question I have now, is that whether or not I should keep the kiln as is, and fire really low fire stuff: Cone 4.  

What is your experience with low fire clays and glazes?

Did you mean cone 04? A 240 volt kiln on 208 volts probably won't get to cone 4.

Cone 04 is just low fire, not really low fire. Really low fire would be like lusters, cone 019.

Do a search on the forum. There are lots of discussions about low fire work vs cone 6.

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On ‎9‎/‎24‎/‎2018 at 4:03 PM, Linh said:

So I just learned that I need to change the elements in the kiln, so that it can fire properly with 208v.  which will cost $400.

 

The question I have now, is that whether or not I should keep the kiln as is, and fire really low fire stuff: Cone 4.  

What is your experience with low fire clays and glazes?

I would not change out my clay/glazes on a kiln issue. As Neil said, you probably will not get that to cone 4 and  it will really make the elements struggle and run longer than they should. 
If the cost is too much on the re-wire (I'm not sure how much you have invested in this endeavor or the condition/size/value of kiln), consider other options. You could sell the kiln and use the proceeds to get a 208v kiln. Another option is to keep this kiln for bisque and purchase a second kiln for glazing until you have the funds to convert the first kiln to 208V.

Just a side note, I see this a lot with people new to kilns, you should have an idea of the electrical specs before making the investment. You should check the voltage and phase of the kiln and also the max firing temperature/cone. Switching a 240V or 208V (or vice versa) is easy, even if costly, but if your phase is incorrect, the problem is  much bigger.

Edited by Frankiegirl

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