KILN ELEMENTS #2
A bit more about kiln elements and their replacement.
Lets say the inevitable finally happens. You've got a broken kiln element. What do you do? Can you replace it yourself?
Yes, you can. If you are someone who is generally handy with hand tools, like a screwdriver and pliers, it is certainly a job you can take-on by yourself. It also gives you the chance to get familiar with the inner workings of your kiln, which may payoff another day.
Before you start, you might wonder if you should replace all of your kiln's elements (assuming pending failure on the others), or just replace the one element that is broken. Generally speaking, it's perfectly Ok to replace just the broken element, if that is what you want to do. Arguably, having one new element among old ones does change the heat balance slightly in the kiln. As elements age, their resistance increases slightly, thus they create less heat. However for most potters, this is not something that would be noticed when firing.
Probably the best reason for changing all of the elements is that you give yourself a fresh start. You can reasonably expect to avoid another element failure for 50-100 firings or more. Also, you are less likely to have another failure an at in-opportune time. (And since you have the tools out any how, maybe you should just do them all.) I'd suggest that you base your decision on the mode of failure; If the element wore out after 100 firings, then consider replacing them all. They may all be on the verge of failing anyhow. If the element broke because a blob of glaze got on it, or you accidently smacked it with a shelf, and it was nearly new, then it's reasonable to just replace the one failed element.
HOW EXPENSIVE ARE ELEMENTS?
Kanthal elements are about $45 each, possibly more (or less) depending on the length of the wire used. A comparable APM element might be $150 or more.
HOW DO YOU REPLACE IT?
When you purchase replacement elements (we have them on our site here), they come with instructions, and you should follow those specifically written for your kiln. That said, the process is something like this:
You will probably need a medium flathead screwdriver, a #2 Philips screwdriver, needle-nose pliers, adjustable wrench or pliers, and (depending on your kiln make), a crimping tool. Allow for an hour on the first element, and maybe 30 minutes per element after that (although the more you do, the faster you'll get).
UNPLUG THE KILN
Access the inside of your controller or KilnSitter enclosure on your kiln.
Remove the existing element. Depending on the manufacturer, that may include cutting a wire crimp off, or disconnecting a wire clamp. You may also have to remove element pins, which may be holding the element into place inside the kiln. Needle nose pliers work great for that.
Carefully inspect the element groove, and remove all debris. Vacuuming is good here.
From the inside of the kiln, feed the straight wire ends of the new element back through into the control box area.
Most elements are already pre-stretched to the correct length, so you just need to evenly distribute the element into it's groove. Then pin it into place.
Connect the elements to the lead wires inside the control box, either by clamping or crimping the wires.
Make a final vacuum of the element groove.
That's pretty much it. Not too hard at all. You'll want to test it before you load up your kiln. The "glowing elements" test I mentioned previously works well for that.
If you have more than one element to replace, I suggest that you do them one at a time. That reduces the possibility of getting confused on which wire goes where when you're putting things back together. I recommend taking a digital photo of the wiring in the control box before you get started. That can be very helpful for this type of job. (This has personally save me a lot of grief when I've needed to re-assemble something.)
IS IT SMART TO REPLACE THE ELEMENTS BEFORE ANY OF THEM BREAK? SHOULD I CONSIDER IT A "PREVENTATIVE MAINTENANCE"?
It is a valid strategy to replace them preventatively. If you can not afford down-time on the kiln (say you have production to run, or it's a school kiln and the semester is starting) then "yes". Old elements also fire cooler than new elements. If you notice your firing times has been slowing increasing, or your kiln is struggling to reach higher cones, then new elements may improve that.
In truth, most people don't think much about their kiln elements until the day they fail. If you're a hobby artist, and you're not under a deadline to fire, that's Ok. It's no big deal, and you can worry getting the replacement elements when they break. However if you're a production artist, or you have schedules or customer commitments to meet, you may want to preventatively change the elements, or at least have some spare elements on hand for your kiln.
Most kilns have approximately one element for every one cubic foot of interior space. Sometimes the elements are all the same, and sometimes there will be 2 or 3 unique element designs (depending on the element's location in the kiln). If you plan to have spare elements on hand, make sure you have at least one of each design. This is another reason to purchase a full set of elements, even if you've only broken one. That way you'll have the remaining set of spares on hand for when the next element fails.
DO ALL ELECTRIC KILNS HAVE ELEMENTS? I DON'T SEE ANY IN MY KILN.
Yes, I think all electric kilns have heating elements, but a few kilns (normally smaller, craft-type kilns, like the Paragon SC2/SC3) will have a "muffle" instead of brick and element construction. A muffle is one-piece assembly comprised of ceramic fiber with the heating element embedded in the fiber. The advantage is that the element is protected in the fiber and can not easily sustain physical damage. The disadvantage is that should the element fail, the entire muffle must be replaced, which is much more expensive than the cost of an element.