What makes elements melt and sag?

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What makes elements melt and sag?

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  • The Knowledgebase is organized into a series of questions and answers having to do mostly with technical troubleshooting and understanding of kilns.
  • Although we write this for our own kilns many of these articles apply to other makes - although L&L takes no responsibility for that.
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  • Actions are specific actions for you to take during the troubleshooting or repair process.
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What makes elements melt and sag?
  1. Getting glaze on the element can cause that to happen.
  2. It can also happen sometimes from a combination of things, not involving direct contact with glaze. For example, the elements in the photograph look pretty worn out. Over their lifetime they are possibly getting different types of glaze fumes and carbon etc. on them. Anything on the surface of the element drives up it's surface temperature. Combine a lot of that with some pottery set too close to an element, reflecting the heat back on to the element right there, and you can get it hot enough locally to melt the element into the element holder.
  3. Glaze fumes can condense on the elements. Good venting can help prevent this.
  4. Be sure to vacuum out element holders to remove any dirt, clay, glaze, etc. that may have settled in there.

Additional Actions to Take

When ordering a new holder provide model number of kiln and length of the element holder. See the Parts List for this information.

Note that if the holder has melted badly you may need to either replace the brick that holds it or at least patch the brick with our Brick Repair Kit.

Method #1:

  1. This method leaves the kiln in tact.
  2. Break up the holder and remove it in pieces and then modify the new holder to snap into the groove.
  3. Using a chisel or large screw driver and a hammer carefully crack the holder that needs to be removed. Take your time with this, the holder can be gradually broken into little pieces.

The holder shown with small pieces broken off of it.

The groove shown with the entire holder removed.

Using linemen’s pliers, snap off the bottom edge of the holder. Make sure that the bottom of the element channel is closest to the edge that you are removing.

A normal holder compared to one with edge removed.

The new holder can now be snapped into the groove in the firebrick. It will hold in place with no cement.

Positioning the holder back into place in the firebrick.

Method #2:

This method requires you to take the kiln sections apart.

  1. Take the section with the bad holder off the kiln and put it on a flat surface like a flat floor or table.
  2. Carefully pull the elements out of the element holders of the brick section involved and allow them to hang loose. Take great care not to hang loose. Take great care not to "break" the element as they are very brittle after firing.
  3. Loosen the adjustable clamps that hold the stainless steel wrapping. Loosen them just enough to allow the brick to slide out with slight hand pressure (so that the other bricks stay in place). 
  4. Pull up the brick with the bad element holder just enough to allow removal of the defective element holder and replace with new one. Slide the bad brick(s) out and put in new brick(s). Be sure the element holders line up with the other holders on either side. Note there is a top and a bottom in the element holder so be sure to get the orientation correct.
  5. Retighten the clamps on the wrap. Alternately tighten the bottom and top clamp so that you don't cock the stainless casing.



CAUTION WITH STEP 3: If you don't have the section on a flat surface then the bricks will all come out of proper alignment.

  1. Order the firebrick precut and rerouted from L&L Kilns. One can order this with the proper element holders already in place or reuse the holders from the old brick. Be sure to order it for the appropriate model of kiln. Be sure to say whether it is a brick where the element connections come through. (Click here for all repair bricks).
  2. Remove the section of the kiln and put it on a flat surface. Elements will have to be removed and properly placed.
  3. Loosen the clamps on the stainless steel band that hold the section together just enough to remove the damaged brick. Do not completely remove the stainless steel case. Loosen just enough to allow the brick to slide out with slight hand pressure while the other bricks stay in place.
  4. Slide the bad brick(s) out and put in new brick(s). Be sure the element holders line up with the other holders on either side. Note that there is a top and bottom in the element holder so be sure to get the orientation correct.
  5. Retighten the clamps on the wrap. Alternately tighten the bottom and top clamp so that you don't cock the stainless casing.
  6. Replace the elements.
  7. Sand off the top surface of the firebrick to match the surface of the other firebricks. Sandpaper will work fine.
  8. Brush a light coat of facing over the top of the brick.

CAUTION IN STEP 3: If you don't have the section on a flat surface then the bricks will all come out of proper alignment at this point.

Resistance and Error 1

  • The most common cause of kiln slowdown, E-1 messages, and failure to reach temperature is element wear. As your elements age they generally increase in electrical resistance.
  • When resistance, measured in Ohms, increases, both Watts and Amperes (amount of power) will decrease, assuming Voltage remains constant. If you don't have enough power, your kiln will fire slowly and might not even reach the desired temperature.

What does this mean?

  • Using resistance, we can tell exactly how much power your kiln has lost over the course of your element's life.
  • For example on an e23T that uses 240V, a brand new kiln section would read about 14.5 ohms. If you measured this same kiln section after many cone 6 firings and the reading was 16.5 Ohms, you would know that this section of elements has lost approximately 14% of it's power (16.5/14.5=1.138, or close to 14%).
  • A very general rule of thumb is that most people will typically begin to notice some slowdown once you've lost more than 10% of your power.
  • It will certainly vary based on the kiln you have, your voltage, as the types of firing you do. People only doing low fire work will continue to get by on lower power than those needing to go to higher temperatures (cone 6).

EASY-FIRE, DURA-FIRE, EQUAD-PRO, LIBERTY-BELLE, DOLL, SCHOOL MASTER

In these series' of kilns a piggy-backed control panel covers up the element terminals.

  1. Turn the power to the kiln completely OFF and unplug it if possible. If it is direct wired, then you should at least turn off all power at the disconnect switch or circuit breaker.
  2. Open the outermost control panel by unscrewing it either from the element cover box in the case of Easy-Fire, eQuad Pro, School Master and Liberty Belle kilns or from the kiln body in the case of Doll kilns.
  3. Once you open up that control panel you will see the element power wire terminal strip. See the picture. It will have numbered wires coming from the element terminal blocks and wires connecting to the power relays. There are two wires per kiln section/ring, so numbers 1 & 2 are for the top section, 3 & 4 for the middle, and 5 & 6 for the bottom section on a three ring kiln.
  4. Set your multimeter to Ohms (Omega symbol Ω) and using your testing leads, place one in between the two tabs/terminals w/ #1 wires connected. There is a small circular divot that the lead fits into (see picture). Put the other lead on terminal #2 and make note of the reading. Repeat the process for 3 & 4 and then for 5 & 6. Remember that each pair of wires represents one section.
  5. Compare your readings to those on the wiring diagram in your instruction manual. Keep in mind that the ohms on the wiring diagram are per ELEMENT while your reading will be per SECTION. See above for more info on understanding the readings.

CHECKING RESISTANCE ON AN EASY-FIRE KILN

JUPITER, DAVINCI

In these series' of kilns, the control panel is separated from the kiln body and the element terminals are connected to the controls via external jumper cords or plugs.

  1. Turn the power to the kiln completely OFF and unplug it if possible. If it is direct wired, then you should at least turn off all power at the disconnect switch or circuit breaker.
  2. Unplug the first jumper cord from the control panel.
  3. Set your multimeter to Ohms (Omega symbol Ω) and using your testing leads, place one lead on each of the "hot" prongs. They will be the flat ones.
  4. Make note of the reading and move on to the next one.
  5. Compare your readings to those on the wiring diagram in your instruction manual. Keep in mind that the ohms on the wiring diagram are per ELEMENT while your reading will be per SECTION. See above for more info on understanding the readings.

CHECKING RESISTANCE ON AJUPITER OR DAVINCI KILN

See this tutorial on how to use a multimeter.

Ohms Per ELEMENT VS Ohms per SECTION (or Circuit).

  • How you figure out the section ohms depends on whether the elements are wired in Parallel or Series.
  • Most kilns are wired in Parallel except for JD230V and most 18" kilns like the e18T.
  • For a parallel kiln you take the per element ohms listed on your wiring diagram and divide by the number of elements per section.

Example #1 (2 Elements in Parallel): e23T 240V 1 Phase: Elements are 28.9 Ohms each. Divide by two because they are in parallel and you will get a reading of 14.5 Ohms per section.

    Parallel element connection for a kiln with two elements

    Example #2 (2 Elements in Series): e18S 240V 1 Phase: Elements are 9.6 Ohms each. Multiply by two because they are in series and you will get a reading of 19.2 Ohms per section.

    Series element connection for a kiln with two elements

    Example #3 (3 Elements in Parallel): JD2927 240V 1 Phase: Elements are 36.5 Ohms each. Divide by three because they are in parallel and you will get a reading of 12.3 Ohms per section.

    Parallel element connection for a kiln with three elements

    Example #4(3 Elements in Series): Doll DLH11-DBX 240V 1 Phase: Elements are 6.6 Ohms each. Multiply by three because they are in series and you will get a reading of 19.8 Ohms per section.

    Series element connection for a kiln with three elements

  1. Unplug kiln.
  2. Remove the Control Box.
  3. Using a 3/8" nut driver or ratchet wrench or adjustable wrench, remove the nuts that hold the element end onto the Element Terminal Bolt. Note that the terminal bolt head is held in place by an inset shape on the underside of the ceramic terminal block and it will not turn much.
  4. Untwist the element end from around the Element Terminal Bolt. Straighten it out as much as possible.
  5. In most cases the element can be lifted out of the holder at this point. Sometimes, if the element has really disintegrated, you need to remove it in pieces with needle nose pliers.
  6. If element is hard to get out of the holders (because of growth of the element) you can try heating up the kiln slightly so as to heat up the element slightly to just the point where element is slightly pliable–don't let it get red. This will soften the wire. Then turn off the kiln and disconnect all power to the kiln. Using heat protecting gloves and a pair of needle nose pliers pull out the softened element.
  7. From the inside of the kiln, using needle nose pliers, grab the element as close to where it goes through the brick wall to Terminal Block. Pull the element end through the hole. Be careful not to enlarge the hole in firebrick. The brick is soft and will not take much abrasion.
  8. Be sure to check for failure points for evidence of contamination on the element and the element holder. If the element holder is contaminated it will cause rapid failure of the new element. Replace contaminated holders with the new ones.
  9. Using your multimeter check the resistance of the new element.
  10. Install the twisted ends of the elements through the holes in the wall of the kiln. Element ends should be straight at this point.
  11. Pull them up tight up to the wall of the kiln by pulling from outside the kiln.
  12. Lay the element into the groove. Note that the unfired element is going to have some springiness to it before it is fired for the first time. You may need to use a screwdriver to press the element into the holder. YOU DO NOT NEED PINS.
  13. FOR KILNS WITH NON-CERAMIC TERMINAL BLOCK OR ON RETROFITTED KILNS WHERE YOU HAVE ADDED A CERAMIC TERMINAL BLOCK BUT STILL NEED BUSHINGS: Be sure to replace the insulators and spacers over the element tails.
  14. Consulting your picture or labeling, wrap the appropriate element tails around the appropriate element connection bolt, clockwise, one around and cut off the excess tail.
  15. Install the elements and hardware: Place the wires from the jumper cord or connecting wires onto the appropriate bolts and tighten with stainless steel nuts.
  16. A washer goes under the first element.
  17. Twist the first element end CLOCKWISE around the Terminal Bolt.
  18. The next element gets twisted around the Terminal Bolt on top of the first element.
  19. Another washer goes over the Terminal Bolt.
  20. Place a nut on top and tighten it.
  21. Put another washer on.
  22. Put on the Ring Terminal of the Power Lead Wire.
  23. Put another washer on.
  24. Put another nut on and tighten it. How much the nut can be tightened is dependent on how tight the element connection bolt is on the element connection board. A tight connection is very important, but if you tighten too much and twist the element on the bolt too far you could break the element, the bolt, or the insulator.
  25. Reattach the ground wires and the element box if the kiln has them. DO NOT FORGET TO ATTACH GROUND WIRES. IF EACH KILN SECTION IS NOT GROUNDED THIS CAN BE VERY DANGEROUS.
  26. Test the resistance at the jumper cord's plug head or at the other end of the connecting wires.
  27. Reattach the control box, turn on the kiln and make sure all the elements come on.

See this tutorial on how to use a multimeter.

See this video: