How do you know when your elements need to be changed?
Usually, after you have a problem with the firing is the short answer.
For example, an incomplete firing:
If you return to a kiln that is unfinished and is showing an error code (i.e. Error 04-01 for a Nabertherm, or Error 1 for a Rohde/Kilncare controller), it may indicate a power problem with your supply. In some circumstances, your kiln can be starved of power by low voltage or insufficient amps due to issues with your own electrical supply, in which case the services of a qualified electrician would be required. However, it can also mean that the elements are weak and struggling, or that they have finally stopped working.
We would suggest that if your number of firings is high, then changing the elements should be considered first. A “high” number of firing cycles is difficult to define, as element lifespan varies widely depending on firing temperatures, kiln loads, venting, types of glazes used, and general kiln practices. Some users achieve well over 100 firings from a set of elements, while others find their elements worn after only 20–30 firings. Taking these variables into account, you should make a judgment based on your own use of the kiln.
If the firings are high for your particular circumstances, replacing the elements is the most likely solution to the fault, and following a logical and scientific troubleshooting approach, it is something that should be ruled out before investigating other possible causes. We would also suggest that, unless your kiln is very large, changing the elements is usually the most cost-effective option when compared with having an electrician attend to check either your supply or the kiln.
A piece of important information we like to have is at what point in the firing did the kiln stall or stop working? Usually, it will be in a second segment - this is because at this point, a faster climb rate will demand more amps. For instance a kiln climbing from 0-600 °C at 80°C p/hr will not need its full amps, but on a second ramp, which might have a fast climb, 200°C p/hr or full power will be requiring all its amps, and this is often where the elements will be at maximum stress, if they are due to go, then it will be at this point.
For example, the kiln is slowing:
If you are experiencing longer and longer firing times, then this is a clear indication of element wear. When elements are used, they oxidise on the surface, and the metal wire used for the electrical current becomes thinner, until it becomes so thin that it breaks. A more fulsome explanation is available here.
For example, heat differential:
On some models, you may discover that you have a difference between the heat at the top of the kiln to the bottom. As a result of this, you may notice that the wares have fired differently. This could be because one of the elements has stopped working and others are trying to compensate for it, hence creating an unevenness in the firing. You will also have to consider that the unevenness could be down to other factors, like kiln load, firing program and too many shelves.
What will help you is knowing the number of firings and of what kind i.e. Earthenware or Stoneware. You can find this information by loading the statistics directly from your controller.
Here's how to find the firing statistics on a Nabertherm B500/AC590 Controller:
On Rohde and Kilncare kilns whatever the controller, the only data available on the controller is the Kw of the last firing done. Here's how to find the firing statistics on a Kilncare controller (the same applies for Rohde's controllers):
For a KCR32C, ST411 x1 and ST310 x2. Refer to the controller manual Rohde ST411 6.7, 63/280. See link. Rohde’s ST310 5.1.5, 14.42. See link.
If you see it written, your parameters must be set before your kW can be read; then this is done at the factory, and you should not need to do this. If you don’t have a Wi-Fi signal needed for Rohde controllers, or you have not bought the Wi-Fi-enabled controller of Kilncare’s, then using a USB memory stick is the best way to obtain a full data log of firings. The controller will record firings, which you can then later upload to their respective websites.
As a backup, it would be useful if you kept a kiln journal. And if you do change your elements, then do make a note of when you did that.
Finally, if you do think a fault is not your elements and you want us to help, then please send us a picture of the serial number/electrical plate like the one below, with an email of your suspicion to info@hot-clay.co.uk
