My small test fire 120V Cress BT911T kiln is not firing to temperature. I have always noticed it fired slowly, but firing to cone 06 it got there eventually.
I recently tried firing to cone 5 and I could not get above 1960 degrees fahrenheit, and going from 1900 to 1960 took 5 hours. I'm controlling the kiln using an SSR, reading temperature with a K-type thermocouple through a MAX31855 with a PID controller running on an Rpi with a webserver hosted.
My kiln elements are measuring at 8.8 ohms, rather than 8 ohms nominal. I am getting 90% of full power.
Would this be enough to prevent a full firing? This seems strange to me.
I am considering replacing my elements, seeing if that fixes my issues, I am not sure though.
Does anyone have experience with these 120V kilns?