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My Kiln turns up at a lower rate that What I programmed it


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Hello everyone!

I have recently purchased a second hand Estrin kiln which I upgraded it by adding a Bartlett controller. 
I have done a few bisque firing with it to cone 05 and I had no problem. However, today as I programmed it to cone 6( set a program with a rate of 260 c (from 105c) to 1080c, the kiln doesnt click as it turns up and it goes up in over hundred degree celsius lower than what is supposed to. I wonder if someone here can kindly help me and let me know what to do? 
I really appreciate your time!

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Oooh! The lore tells us of the Estrin kiln! There was one guy that made them in Vancouver. He retired over 20 years ago, and no one took over for him. From all accounts they were over-engineered, and you still see one turn up every now and again. When you added your controller, did you also replace the elements and relays? If not, do you know how old they are? Have you got an original manual, or access to the specs of your model?

The clicking sound you hear from your kiln is the relays turning on and off, which controls the intensity of the heat coming out of the elements. Usually in the early part of the firing this cycling is more frequent so that the climb is slow. A climb rate of 260 C is pretty speedy, especially through quartz inversion, so the less frequent clicking isn’t surprising.

Why the speedy firing?

I’m gonna tag both @neilestrick and @Min on this one. 

Welcome to the forum!

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5 hours ago, Mitra said:

the kiln doesnt click as it turns up and it goes up in over hundred degree celsius lower than what is supposed to. I wonder if someone here can kindly help me and let me know what to do? 
I really appreciate your time!

The elements are likely worn so much so that the kiln cannot make the programmed rate. The Bartlett controller contains some parameters that account for the typical power of the kiln and the expected rate of energy loss through the shell.

Best idea that strikes me is find out the element resistance, then measure to see if it has gone up by 10% or more. If it has, this pretty much confirms they are worn out and not capable of the higher temperatures and need replacement. With new elements there is a reasonable chance the Bartlett control will match with its default programming and behave as expected. Minor tweaks can be made to the Bartlett from there to better match the kiln if necessary.

Bisque firings generally don’t exceed 100c per hour BTW mostly to ensure complete burnout. Fast glaze firings generally can go as fast as 300c per hour.

Edited by Bill Kielb
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I would measure the resistance of the elements to start with. Then I would take a photo of the faceplate with all the specs clearly visible and send it to Jay Clarke at Pottery Supply House (same company as Euclids ). Ask them what elements are needed to run a kiln of the model you have. Ask what the resistance of the elements would be for new elements and compare it to what your readings are. Is it a 10 cubic foot one? Reason I ask is they made 2 versions of the top loading electric 10 cu ft ones. On one version the elements wrapped around the kiln once, on the other version they did two loops.  Open up the box and take a picture of that to send to Pottery Supply House / Euclids also.

Those double thick walls on the Estrins mean the kiln will take much longer to cool down than the typical electric kiln. (I had an Estrin kiln many years ago, never did come across a manual or wiring diagram for it)

 

Edited by Min
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@Callie Beller Diesel Thank you for your response Callie! 

I actually didnt change the controller myself and I asked the technician in town to replace it for me. He looked at the relay and the wires and he said they dont need to be replaced. I am not so sure how old they are but I know the person who was using it before me was firing this kiln only and only to cone 08 for so many years. The bricks and wires all look they are brand new.

The model of this kiln is Q8c and unfortunately I dont have any manual for it.

The reason that I also chose 260deg C upto 1080c was because of the program that I had from school which we tested so many times and I also checked the firing program by John Britt https://glazy.org/kilnschedules/238 and another program by Tony Hansen https://digitalfire.com/schedule/c6dhsc and they all look really similar. My assumption was this program is reasonable and I should be able to do that. 

Once I realized the kiln can not fire that fast I changed the program to 150 deg C and the problem still existed and the relay was not still clicking. My question at this point is, if the kiln can not be fired as fast as I programmed it and it takes much longer, does it mean I should adjust the program since the wares are in the kiln for longer and reaching a certain cone is not just about the temperature and it's the combination of temperature and time?

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12 hours ago, Bill Kielb said:

The elements are likely worn so much so that the kiln cannot make the programmed rate. The Bartlett controller contains some parameters that account for the typical power of the kiln and the expected rate of energy loss through the shell.

Best idea that strikes me is find out the element resistance, then measure to see if it has gone up by 10% or more. If it has, this pretty much confirms they are worn out and not capable of the higher temperatures and need replacement. With new elements there is a reasonable chance the Bartlett control will match with its default programming and behave as expected. Minor tweaks can be made to the Bartlett from there to better match the kiln if necessary.

Bisque firings generally don’t exceed 100c per hour BTW mostly to ensure complete burnout. Fast glaze firings generally can go as fast as 300c per hour.

Thanks a lot Bill for your response! 

Since I am completely new  and I have never tested the element resistance of my kiln, do you mind telling me what number should I look for or what do you mean by "then measure to see if it has gone up by 10% or more." ? What number should I compare it with?

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12 hours ago, Min said:

I would measure the resistance of the elements to start with. Then I would take a photo of the faceplate with all the specs clearly visible and send it to Jay Clarke at Pottery Supply House (same company as Euclids ). Ask them what elements are needed to run a kiln of the model you have. Ask what the resistance of the elements would be for new elements and compare it to what your readings are. Is it a 10 cubic foot one? Reason I ask is they made 2 versions of the top loading electric 10 cu ft ones. On one version the elements wrapped around the kiln once, on the other version they did two loops.  Open up the box and take a picture of that to send to Pottery Supply House / Euclids also.

Those double thick walls on the Estrins mean the kiln will take much longer to cool down than the typical electric kiln. (I had an Estrin kiln many years ago, never did come across a manual or wiring diagram for it)

 

Thank you Min for your answer and all your advice! I will check the resistance of the elements and will be in contact with pottery supply house then. ( I just need to figure out how as I have never done it before:rolleyes:)

The kiln is 8Qc which I believe it means that it is 8 cubic foot. I have attached a picture of my kiln here which shows there that elements wrapped around only once.

 

 

20211108_153828.jpg

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3 hours ago, Mitra said:

I have attached a picture of my kiln here which shows there that elements wrapped around only once.

 

Can’t actually see if your kiln has the double length elements from the photo.  I believe it was only on the 10 cu ft kilns that some were made with double length elements, since yours is smaller it probably isn’t. 
 

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11 hours ago, Mitra said:

Since I am completely new  and I have never tested the element resistance of my kiln, do you mind telling me what number should I look for

I think @Min idea of photo, faceplate, and calling the pottery supply house is a great way for someone to tell you what the element resistance is new. For measuring element resistance it is something you will need to learn how to do. There are several videos on the net that you could watch to learn this, although not your specific kiln, this video teaches the concept of measuring each ring: https://youtu.be/oq6A9LRf5Es. Maybe a good opportunity to learn as well but if not it’s not for everyone and kiln technicians have real skills.

11 hours ago, Mitra said:

The reason that I also chose 260deg C upto 1080c was because of the program that I had from school which we tested so many times and I also checked the firing program by John Britt https://glazy.org/kilnschedules/238 and another program by Tony Hansen https://digitalfire.com/schedule/c6dhsc and they all look really similar. My assumption was this program is reasonable and I should be able to do that. 

A rate of 260c per hour gets an 04 bisque done in four hours, so maybe a misunderstanding or misprint but definitely not good practice to effectively bisque fire most wares. The Britt program reference is for a fast glaze. The digital fire program references a glaze fire. The speeds I mentioned above are consistent with these schedules for fast glaze. The range of speed I mentioned for bisque is very common as well.

11 hours ago, Mitra said:

since the wares are in the kiln for longer and reaching a certain cone is not just about the temperature and it's the combination of temperature and time?

I think a super good question and the answer is: yes, in the last 100c of the firing. If you look at a cone chart you will see columns labeled rate per hour. The cone will bend at that temperature fired at that rate in about the last 100c of the firing. A super good question, of which it seems cone theory is not often taught effectively anymore. 

If all else fails and you post the picture of the name plate on the kiln we can derive what the total resistance of the kiln should be. The call to Euclids is probably easiest and most accurate though.

 

Edited by Bill Kielb
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20 hours ago, Bill Kielb said:

I think @Min idea of photo, faceplate, and calling the pottery supply house is a great way for someone to tell you what the element resistance is new. For measuring element resistance it is something you will need to learn how to do. There are several videos on the net that you could watch to learn this, although not your specific kiln, this video teaches the concept of measuring each ring: https://youtu.be/oq6A9LRf5Es. Maybe a good opportunity to learn as well but if not it’s not for everyone and kiln technicians have real skills.

A rate of 260c per hour gets an 04 bisque done in four hours, so maybe a misunderstanding or misprint but definitely not good practice to effectively bisque fire most wares. The Britt program reference is for a fast glaze. The digital fire program references a glaze fire. The speeds I mentioned above are consistent with these schedules for fast glaze. The range of speed I mentioned for bisque is very common as well.

I think a super good question and the answer is: yes, in the last 100c of the firing. If you look at a cone chart you will see columns labeled rate per hour. The cone will bend at that temperature fired at that rate in about the last 100c of the firing. A super good question, of which it seems cone theory is not often taught effectively anymore. 

If all else fails and you post the picture of the name plate on the kiln we can derive what the total resistance of the kiln should be. The call to Euclids is probably easiest and most accurate though.

 

Thanks a lot Bill for your answer and sending me the link!

The rate that I shared was actually for cone 6 glaze firing with slow cool. After realizing the kiln can not fire as fast as I programmed it, I set that segment to 150deg C to 1080C instead of 260C. Today I unloaded the kiln and the kiln overfired.  I guess I just need to adjust the top temperature from 1210C to something around 1200C next time.

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82CAF482-1B56-4154-94D0-DCC3DBF61156.jpeg

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Bisque firing rate
Again 100c per hour for bisque would be common, I don’t think I would go faster than 120 c per hour which gets you an eight hour bisque.

Cones
if you are following the instructions on the Orton cone chart, the very last 100c of the firing would be done at a rate of 60c per hour (center column of the Orton cone chart) to get you close to making your cone drop at the temperature published in the chart. Link to chart and instruction https://www.ortonceramic.com/files/2676/File/orton-cone-chart-2016.pdf

Element resistance best guess
Based on your picture and nameplate, your kiln draws 45 amps at an assumed voltage of 240 v ( this is a guess because it is hand written and the voltage is a range) All your elements totaled would measure 5.33 ohms in parallel. Which means depending on how many elements there are they would be a multiple of 5.33. So for 4 elements, 4x5.33 =21.32 ohms for each element.

There is a bit of guessing going on here from that equipment tag since the voltage is written as a range, a call to Euclids is definitely the easiest most accurate way to find the element resistance 

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