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Pugaboo

Replacing Thermocouple

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I just opened the kiln from my test run and I am definitely running a full cone hotter than I should or that I have been. Everything I have been able to find says this most likely means my thermocouple is drifting. I've gotten no error messages so I guess I could just fire a cone lower but am leaning towards just replacing it.

 

I have a new thermocouple here in a box and think it's not too hard to install. Any pointers anyone?

It's an Freedom Olympic 1823HE with a Bartlett controller.

 

What I have read seems to say:

Unplug from power and open front plate, carefully pull open and locate thermocouple heading into the wall. I will take a picture at this point for reference so I know how everything looked before I touched it. Follow wires to the circuit board from thermocouple and since I only have one the wires should be on the #2 connectors, 1 red and 1 yellow. Carefully unscrew from board and remove, watch how the wires are fed across board and match placeKent and color to color to replace. Strip new wires 3/8 of an inch and screw firmly in place but be careful to not to break the wire. Close back up and run a test fire to cone 04 with only test cones on shelves.

 

Questions:

Do I need to calibrate the thermocouple?

What am I missing?

 

I should note that I have built computers from the circuit boards out, replaced oil pumps, rebuilt carburetors, replaced air conditioning blower fans, ice makers, etc etc etc. I'm the handy dandy girl around here so unless there is a reason to hire someone I would really like to learn to do this myself. I have just had a hard time getting good solid Intel on the procedure.

 

Thanks for your help!

 

T

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Pugaboo - I just replaced the thermocouple in my Olympic 2327 HE with Bartlett contoller. The main point stressed was to be sure to get the kao-wool or the fabric that came with it, completely surrounding the thermocouple so as not to have the heat blow back thru the tube and onto the controller. Mine came with the wire already stripped back. One thing, I fire my kiln to 2192*F. With the old thermocouple that was a self supporting base cone 6 to about 3 o'clock according to Orton pictures. But the new thermocouple fired to 2192 put the cone 7 at tip touching. I am going to reset the top end to 2185 and see what that gets me - unless some of the professionals on this forum have a better idea.

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I just got off the phone with Olympic and they said there should have been some in the repair kit that came with my Freedom so they are sending me out the missing insulation.

 

T

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Dh - mine looks like the 3rd one on the far right. I don't see any separation between the two wires on either the old or the new. They both seem to be inside of a steel tube and have a rounded end.

 

I have attached a picture of the old one. It looks really crispy and the back dusting you can see around it is new as well.

 

T

post-22921-0-28766100-1462461181_thumb.jpeg

post-22921-0-28766100-1462461181_thumb.jpeg

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Wait, why is the case made out of metal? I thought they were all some ceramic stuff.

 

The two wires in the sensor end need to be soldered 'round bit' together to get the voltage difference over temps. My thermocouple has screws terminals on the sensor end to replace so no taking out of the board but it is easy anyway. Swap out two wires and put it back.

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Here is a picture of the new one.

 

T

Just replace the wires on the terminal board just the way they came off.  I wouldn't add any solder to the wires, this will add another dissimilar metal and could introduce unwanted errors in the the readings.  You will just do fine replacing the thermocouple your self.

David

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There are several types of type K thermocouples. Some are thick with exposed ends, some are thin with exposed ends, some are sheathed in metal, some are in a ceramic protection tube. HERE is a test L&L ran with lots of different types. They determined that the 8ga exposed ends put into a ceramic protection tube was the best bang for the buck- 139 cone 10 firings.

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They all do that if there's exposed metal. Most of the ones we use here in the US are open tips, with ceramic sleeves covering the rest of them and keeping the two rods form touching anywhere but the tips, but the exposed tips will shed like crazy. The hotter you go the more likely it is to happen.

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Mine didn't really start shedding until just recently. I know now that it's a sign that it's getting ready to need replacing. I never did get an error message from my controller but I am going to replace it since everything points to it being the reason my kiln is firing differently. I am waiting for the insulation fiber to arrive from Olympic then I will be replacing it and be back up and running.

 

On another note my new L&L test kiln will be arriving Monday and I am excited to get a look at it!

 

T

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I fired my thermocouple without he sheath for years..it was going to cost$70 AUS. to replace the sheath alone..Ex Scot here. Anyway the wire, type R thermo. was a shiny platinum?? alloy, it  never spalled or changed in appearance.

I do like the black colour as it is more visible. My sheath was shattered when a friend helped to unload the kiln. nuff said.

I am amazed how little the new kin thermo. protrudes in to the interior of the kiln.

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I just finished installing my new thermocouple. I had to wait for my kao wool to get here before I could do so.

 

I created a step by step picture album for those of you curious as to what's involved in the process. Not sure if a link to my gallery here will work or not, but hopefully it will:

http://community.ceramicartsdaily.org/gallery/album/1200-replacing-my-thermocouple/

 

It was actually quite easy and even with stopping to take pictures took me less than an hour to do. The kiln is running its first test firing with a fast glaze program to cone 04 as I type. Keep your fingers crossed I did everything correctly!

 

T

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Well documented PugaBoo!!!  I forgot all about that #$%/? set screw - what a pain in the arse!! Took a while to get the screw lined back up, Thankfully my wife's smaller fingers came to the rescue with me only having half a Left thumb. HA!

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To kind of wrap all this up for future searchers...

 

I did a test fire of the new TC and it seemed to be firing about 15 degrees too hot. I did a 15 degree TC offset and fired another test load and everything came out perfect, the self supporting cone 5s came out perfectly bent on every shelf. Yay me!

 

I just finished firing a regular full load of transfers and the cone 05s bent perfectly and all the pieces came out beautifully. Double yay me!

 

I am so glad I figured out the issue and decided to do the repair myself I learned a lot and found out it really isn't all that mysterious and hard to replace a thermocouple. You all were an amazing resource for this and I can't say how much I appreciate each and every one of you.

 

T

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