Monday, April 16, 2012

Kiln Troubleshooting

Well - I'm back. Back from some serious time away from the torch and from glass. I think I would like to say that time spent at the torch is not deducted from your allotted days on earth.

Anyway - while I have many new insights on eldercare and aging - having spent a lot of hours staring in the mirror of my future - this blog is about lampworking - so I will save those insights - with the exception of the following: Do the things you love. Do them now. You might live a long, long time - and maybe you'll have another 40 or 50 years to do the things you love - but it would be tragic if you lived another 50 years, but were incapacitated and couldn't do them. Like arthritis robbed you of the fine motor skills in your hands, or you had the physical skills - but not the mental capacity to be trusted with a torch.  

So - as you might imagine - a break of some weeks and I was itching to get back to the torch. As soon as I could, I fired up the kiln, and went off to load the dishwasher while it was heating up. However, apparently my long break without my regular sacrifices of bad beads and exploding rods to the glass gods had angered them, and when I returned to my kiln, it was blinking a message for me - not the happy and warm message of 972 - my temperature of choice, but tcL - alternating with the distinctly chilly 74 of ambient room temperature.


I dug out the manual - which - in defiance of all expectations - I have read and do keep handy for reference. However, there was no mention of a tcL error message - but it did say that tcF was a "themocouple failure." Hmmm. Not a good thing.

I went to the Paragon website for more insight into the error message - and downloaded a newer version of the manual. (Here is a link to it - for the 4.0 controller - just in case you need it. )

The manual was very helpful, and said that tcL is "thermocouple lag" - which is 

The heating rate is slower than 9°F / 5°C per hour, and the actual kiln temperature is more than 100°F / 56°C away from the programmed temperature. The tCL alarm becomes inactive above 500°F. To return to the display, press any key.
  1. Worn or burned out elements, defective relays, low voltage, and defective thermocouple.
  2. On kilns that use a portable controller, the thermocouple has fallen out of the firing chamber.
  3. A bare spot on the thermocouple lead wires has touched a grounded object inside the kiln switch box causing the thermocouple to short out.
  4. You have programmed a cooling segment temperature that is below room temperature.

I could eliminate 4 easily by checking the program. 2 was also easily eliminated - not a portable controller. As it had been working, and it hadn't been moved - 3 seemed unlikely - so something in the #1 cause seemed the most probable.

I held a lit lighter up near the thermocouple - and the temperature readout started to climb - ok - the thermocouple still works.

Checking out the elements was tricky - because it means sticking your head in the kiln - until my s.o. came along and pointed out that I could just use my cell phone camera - just take a picture and then look at the picture.

Good idea! The cell phone can also just provide illumination if that's what you need.

At that point - he got involved and unscrewed the controller and went at it with a multi-meter and determined that the relay had failed. I can do a lot of things - but poking around with a multi-meter and getting meaningful results is not one of them.

A quick phone call to Jean at Nortel had Paragon calling me back, and confirming the part I needed. A replacement relay was overnighted and hubby installed it - and I was back in business 36 hours from the initial failure.

Kudos to Paragon and Nortel for their outstanding customer service. I wish more companies understood that customer service is a value, not a cost! And thanks too to Dan for diagnosing and installing it! ;-)


  1. Anonymous8:49 a.m.

    Thanks for the tips on insight to aging and Paragon. I have Three Paragon kilns.

    I believe that Life is an Adventure (best shared)

  2. I've had a relay failure twice on my Paragon SC2. The first time I had a lot of help from Kilncare, even though it wasn't one of their kilns. Then helped me to source a replacement relay.

    The second time, I had more luck searching for a new relay myself. By far the cheapest source I could find was .

    I now keep a spare relay, ready for when it happens again :) It appears this is a common fault with the SC2 - since posting about my experience on a lampworking forum, I've had a few people contact me to ask where to get the relays and how to fit them.

  3. Thank you for the link. It is a heart stopping moment when the kiln doesn't work!

  4. Thank you once again for sharing your info! I just set up shop after I moved and went to use the kiln for the first time and got the tcL message. Using your quick instructions and link (the manual is in a box somewhere...) I could diagnose the problem - in this case a bad thermocouple. Major drag and a huge delay but no panic.

  5. Does the relay still click if it is stuck? Mine is clicking, and the thermocoupler seems to be intact since I touched it and the displayed temp went up. I live in Austria and the "local" kiln guy is 4 hours away.

  6. I don't know - I don't know if relays "stick." I'll ask someone.