Replaced Thermocouple In L&l

[jmpeden]

I replaced all 3 thermocouples and put a new relay switch in my L&l easy fire, now instead of slow glaze stopping at 13 hours it is only taking 12 hours and 15 minutes to complete. I did put the ware in before the kiln had completly cooled down from last firing. I think it was showing like 120 defrees when i put in. Would that mess the scheduale up or could it be the thermocouples?

[Dick White]

The L&L EasyFire kilns have the thermocouples in a protective porcelain tube, and therefore the default settings on the controller have a TC offset of 50 degrees. Thus, the normal reading on the controller display at room temperature will be around 120 degrees. At the other end of the firing, it is possible that the new thermocouples generate a different, higher reading than the old worn ones, and so the controller thinks it has reached the target temperature sooner than it did before. The only way to test is to put real cones in your next few firings and see if the kiln is actually performing the expected heatwork.

 

Regarding the new relay switch - if the old relay was stuck in the off position, then it would be reasonable to expect a firing to finish sooner because now you have all sections firing.

[neilestrick]

The offset only 18 degrees.

 

If the kiln wasn't totally cool that would definitely account for the difference. But the thermocouples themselves could also be the culprit. If they were very worn and not reading accurately it could slow down a firing as the controller tries to even out temps in the sections.

[Dick White]

The offset only 18 degrees.

Yes, my bad, the factory default is 18. I have mine set to 50 because I find that I get ^6 at 2195 on a bare thermocouple vs. the Bartlett programmed 2226 (31 degrees needed there) plus the 18 recommended for the protection tubes puts me at an offset of ~50. Then fine tune each zone +/- a couple of degrees.