What to do if the kiln fires slowly?

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  • See the Sales FAQs for Frequently Asked Sales and Preorder Questions
  • 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.
  • Many Knowledgebase articles have Actions, PDFs and Videos associated with them.
  • Actions are specific actions for you to take during the troubleshooting or repair process.
  • Each Action may also have Videos and PDFs associated with it and, in addition, specific Cautions.
What to do if the kiln fires slowly?

Incorrect Loading

  1. If your kiln is loaded unevenly it can cause the 3-zone control to slow the kiln down to compensate.
  2. Try evening out the load. A common mistake is to put too much heavy work in the bottom of the kiln.
  3. Also try to space the bottom shelves so that there are two elements inbetween the shelves. This allows as much of the heat to be transmitted to the work.

Bad or Wrong Voltage

  1. Check your voltage. Do this at the kiln at the Power Terminal Block with the control panel open or check it at your fused disconnect box. CAUTION: This test should only be done by an experienced person familiar with electricity and its dangers. You need to see what the voltage is when the kiln is firing. Low voltage will make the kiln fire considerably slower. For instance a kiln designed for 240 volts will have 25% less power when operated on 208 volts. Check voltage at your panel and where the kiln is connected. Check the voltage when the kiln is firing and when it is not firing. Sometimes the high amperage draw of the kiln will cause a voltage drop at the kiln. A voltage drop of 5 to 10 volts is not uncommon and is to be expected. If your voltage drop is more than that then you may have a problem with your electrical supply.
  2. Make sure no other large electrical appliances such as a clothes dryer or electric oven are on when you are operating your kiln. This may cause a voltage drop which would slow the kiln down.
  3. Voltage may vary in your area depending on season and time of day. Frequently there are "brown outs" during the summer months in some areas. This is when the electric utility reduces the voltage. Try firing at night after peak electrical use hours. You can use your Delay feature to do this easily. Find out from your local utility company when the end of the peak period of electrical use is. Some utilities offer preferential rates for using electricity at night because it is cheaper for them.

Element Aging

  1. See troubleshoot-elements.pdf.
  2. See some of the factors that affect element life.
  3. See What makes elements melt and sag?

Power Relays

  1. Power Relays may cause poor transfer of power to elements when they have been used for a long period of time. It is not always a total failure - which is of course harder to troubleshoot. If these are suspected replace them. See this page for how to check your power relays.

Bad Wiring

  1. Have an electrician check your wiring. We have seen aluminum wire cause intermittent problems with allowing enough voltage through. We do not recommend aluminum wiring although some electricians will swear by it. The problem with it is that aluminum oxide, which is formed from heat, is a resistor while copper oxide is not a resistor. With kilns you will often develop some heat in the electrical lines. If all connections are perfect and the wire is oversized you probably will not have a problem - but why take that chance? Make sure your wires are of the proper size and that all connections are good.
  2. Check your circuit breaker for proper operation. These sometimes go bad over time.
  3. If all the elements are firing and the kiln is still firing too slow check the amperage draw of the kiln under a full load. CAUTION: This test should only be done by an experienced person familiar with electricity and its dangers. You need to see what the voltage is when the kiln is firing.
  4. On a kiln with a DynaTrol you can tell if all zones are firing by pressing the number 8 on the control numeric pad. You will see one little light per zone under the numbers on the control display. If you see two dots on an e23S or e28S, then you are firing at full load. If you see three dots on an e23T or e28T, then you are firing at full load. See if the amperage drawn is the same as what the kiln is rated for. See the product literature and/or data nameplate on the kiln for the rated amperage draw. There is also a complete table of this information in the Installation Instructions part of this manual. For instance, a model e23T rated for 240 volts, Single Phase should draw 48.0 amps. If it is substantially less than the rated amperage draw and your voltage is within 5% of the rated voltage (for instance 230 volts for a 240 volt unit), then chances are the elements have changed in resistance. This will require element replacement. Pressing the number ”8” will turn on 2 or 3 small LEDs that indicate whether the various zones are firing.
  5. The gauge of the hookup wire is not large enough which creates a voltage drop and reduces power to the kiln. See this link for more information.

Wiring in the Kiln

  1. Unplug kiln.
  2. Trace wiring for missing or bad connections.
  3. Check wiring against wiring diagram. Especially check parallel vs. series wiring of the elements.
  4. Check for corroded connectors or connectors that have frayed wires. Replace the damaged parts if you see this.
  5. Make sure all kiln sections are plugged in (if applicable to your model). Make sure ALL plug connections are good and not oxidized.

Element Connections

  1. The holes where the elements go through the firebrick walls are too large. This could cause too much heat to escape from the kiln thereby overheating the element terminals. This can be remedied by lightly stuffing non-RCF ceramic fiber in the element holes. (See the Parts List for non-RCF fiber). You can stuff this in from the inside of the kiln using a sharp tool like a very small screw driver.
  2. Check to see if the element ends are twisted properly. They should be twisted clockwise around the terminal screw. If the twist is too loose this could generate extra heat at the element ends. Check for corrosion on the terminal. If there is corrosion sometimes you can remove it with a wire brush. Photo of element terminal with element end twisted around it properly:
  3. The element connection hardware may not be tight enough. A loose connection can generate heat and cause oxidation of the hardware which in turn will cause a worse electrical connection (because of resistance) and more heat. Replace with new hardware.

Heat Leakage & Vents

  1. Make sure peephole plugs are in.
  2. Make sure hole for vent is proper. Check Vent-Sure instructions for proper hole sizes.
  3. If you are using a different brand of vent make sure it is the appropriate size for your kiln. Check with the vent manufacturer and tell them how many cubic feet are in your kiln.
  4. If your lid or bottom is cracked check to see if it seems to be leaking much heat at high temperatures. Patch or replace if extreme. Some cracking is OK.

Single vs Three Zone Control (DynaTrol Only)

  1. Three zone control will slow a kiln down. It helps even out the temperatures in a kiln by shutting off one or more zones while firing. In addition zone control introduces other issues like LAG (on older controls) that sometimes complicate a firing. The first thing to try if you are getting a slow firing is to switch the kiln to single zone operation. That may get you back into operation quickly. Then, if that makes the problem go away you can fine tune the specific issue within the zone system that is causing the problem.
  2. Normally Easy-Fire, Jupiter, DaVinci and most other L&L kilns with a DynaTrol are programmed to be either two or three zones. You can easily change this to be single zone operation.
    Press OTHER, 4, 4, 3
  3. The display says notC This stands for “number of thermocouples”.
  4. To run the kiln using only one thermocouple press ENTER at the notC prompt. You will then see 0003 or 0002 (depending on whether it is currently programmed for three zones or two zones). Then press 1, then ENTER. The display will then say StOP. All the zones of the kiln will turn on and off simultaneously when you program the DynaTrol to use only one thermocouple.
  5. To run the kiln using only two thermocouples press ENTER at the notC prompt. You will then see 0003 or 0001 (depending on whether it is currently programmed for one zone or three zones). Then press 2, then ENTER. The display will then say StOP. When you program the DynaTrol to run using only two thermocouples the bottom zone and the middle zone go on and off simultaneously. If you have a three section kiln the bottom section and the middle section will work off the middle (#2) thermocouple and they will fire together. This configuration can be an interesting option to help speed up the kiln but still get some advantage from the zone system.
  6. To run the kiln using three thermocouples press ENTER at the notC prompt. You will then see 0002 or 0001 (depending on whether it is currently programmed for one zone or two zones). Then press 3, then ENTER. The display will then say StOP. If you choose to do this thermocouple #1 must be in the top zone, thermocouple #2 in the middle, and #3 in the bottom. All three zones will operate independently, tied to their respective thermocouples.
  7. To exit the OTHER-4-4-3 series of menus without doing anything press OTHER until you come to PCt. Then press ENTER twice. You will then see CPL, and then IdLE, tC2, and the current temperature cycling in the display again.

ShtO (Shut-Off) Setting (DynaTrol Only)

  1. This option is used to shut off the automatic feature in the DynaTrol that holds the hottest part of the kiln at each segment's set point until the average of the three (or two) thermocouples reaches that set point. This can have a dramatic effect on speed of firing and is worth trying to see if it helps you if you are having a problem.
  2. When you press OTHER, 4, 4, 3.
  3. Press OTHER until ShtO is displayed.
  4. Pressing ENTER here allows you to toggle, using any number key, between On and OFF.
  5. On means that as soon as the hottest zone gets to the segment's set point the entire kiln switches to either the "hold time" or the next segment. This will result in a quicker firing.
  6. OFF means that the DynaTrol will not let the hottest zone's temperature rise until the average temperature of the three zones reaches that segment's set point. Then the kiln can begin the "hold time" or the next segment. This will result in more even firing.
  7. When you have the setting you want shown in the display (On or OFF) press ENTER. CPL will display for a few seconds and then IdLE , tC2 and current temperature.

PId Setting (DynaTrol Only)

  1. This setting generally should be left at its factory default because it is hard to predict the changes that it will create in your firing. However, a full explanation is given for more advanced users who want to experiment with this.
  2. This setting comes pre-programmed at the factory for 65%. Basically this setting determines how much help the middle zone of the kiln gives the bottom zone of the kiln when the bottom zone is lagging behind during heating. This comes into play when the bottom zone is on 100% of the time. With this feature, the middle zone of the kiln will come on the programmed percent (Pld) of the time that the TOP zone comes on, if the bottom zone is on all the time. Tests showed that if the bottom was on 100% of the time, the top zone was generally on 90% of the time, but the middle zone was on only about 40% of the time. By programming a higher percent you can greatly speed up your firings. (you will have to experiment, try the factory setting 65% then try maybe 100% and compare your results). Basically the higher the PId setting the faster the firing at the potential price of unevenness.
  3. As your elements age firing by firing, this setting will activate earlier and earlier in the firing because the bottom will be working at 100% earlier and earlier. This will allow the artificial inflation of the center's temperature sooner and sooner. Because this center is heating based on mathematics now and not it's own thermocouple's reading, it will have a longer and longer period of time to get hotter than the top and the bottom. In some cases this can lead to gross unevenness. You may find yourself dialing down the PId to something like 50% or 60%. Remember that if it is set around 40% (it's normal operating percentage) or below, the thermocouple's reading then will be the control for that section, not the mathematics of the PId feature.
  4. When display flashes IDLe, tC2 press OTHER see rSEt. Press 4, 4, 3. See notC
  5. Keep pressing OTHER to cycle through the menu options until you get to PId.
  6. Press ENTER. See PCt, 0085 cycling.
  7. Press any number from 0 to 150, see the number you have entered preceded by a zero like 0120 if you entered 120. Press ENTER, see CPL or StOP for a few seconds, then IDLE, etc.
  8. Pressing ENTER here allows you set another percent setting that can help a slow, heavily loaded kiln fire faster.

Adding More Insulation

  1. In L&L's top loading kilns an additional bottom may be placed under the original bottom. This will improve the insulation in the kiln, thereby slowing heat loss and speeding the firing time. You can also put a 2” layer of calcium silicate on top of the stand beneath the bottom of the kiln.
  2. Also try raising the height of the kiln from the floor or putting a reflective stainless steel or aluminum sheet under the kiln. All these things keep the floor from absorbing the radiant energy from the kiln and will improve heat up times (as well as bottom of the kiln uniformity).
  3. Put a 1” layer of non-RCF ceramic fiber on the lid. This is completely non-hazardous which is important in this application because you will be releasing fibers into the air when you move it while loading. While this is a somewhat extreme measure we have found that a disproportionate amount of the heat loss from a kiln is through the top. Non-RCF ceramic fiber is soluble in the body and is considered totally safe. (See the Parts List).
  4. Whatever you do be sure NOT to put the kiln directly on the floor. If the floor is cement or other hard non-flammable material it will absorb the heat from the kiln. If the floor is wood or other flammable material you will create a very DANGEROUS situation which could cause a serious fire.

LAG Setting (On Older DynaTrols Only)

  1. Note: This option does not show up on controls made after about 2005.
  2. LAG is the zone control setting that determines the temperature differential allowed between zones.
  3. The lower the LAG number the more even the firing. However, this can slow the kiln down considerably. It is somewhat like a convoy - the kiln can only move as fast as its slowest zone (although of course it is more complicated than this because the faster zones help heat the slower zones).
  4. The default LAG setting is 25. If you increase this to 50 or even 75 is allows the kiln to fire its zones with a greater differential which will speed the kiln up.
  5. Press OTHER until you see LAG.
  6. Hit ENTER.
  7. You will see LAG and a number such as 0025 flash.
  8. Input a new number (from 5 to 99) with the keypad and hit ENTER. We do not recommend less than 25 unless you have a very critical process and where speed is not an issue like on low fire. A very low number like 0005 could really slow the kiln down. If you want lower than 0025 try 0015 or 0010.
  9. AUL6 (Autolag) will now display, flashing with either On or OFF. See next section.

Autolag Setting  (On Older DynaTrols Only)

  1. Autolag automatically disables the LAG control until the end of the firing.
  2. Having Autolag turned On speeds up the firing considerably. Most ceramics applications do not require exceptional uniformity until the end of the firing. With Autolag On the LAG feature is disabled until the last 45°F of the firing when it comes back on to it's programmed setting. Basically this allows the faster sections to help pull the slower sections along.
  3. However, for glass and other industrial applications turning OFF Autolag is probably recommended.
  4. Press OTHER until LAG appears.
  5. Press ENTER.
  6. As soon as you press ENTER after entering the LAG setting (you can leave it as is - just press ENTER) you will see AUL6 for approximately two seconds, and then see either ON or OFF.
  7. Press 1 to toggle between ON and OFF.
  8. Then press ENTER

For Manual Kilns Only

  1. Check many of the same things as you would for an automatic kiln like element resistance, wiring, etc.
  2. Switches are sometimes defective.
  3. Relays or contactors may cause poor transfer of power to elements when they have been used for a long period of time. Examine contacts for wear. Replace contactors if contacts are worn or pitted.
  4. Make sure all elements are firing. You can do this by simply looking inside the kiln while the elements are on. They should all be glowing a similar color red. CAUTION: In most kilns the power does not turn off when you open the lid. Be careful not to put your hand inside the kiln while it is on. Dangerous electric shock could result.
  5. If all the elements are firing and the kiln is still firing too slowly, check the amperage draw of the kiln under a full load, i.e. with all Infinitely Variable Zone Input Switches on 100%. See if the amperage drawn is the same as what the kiln is rated for. See the product literature and/or data nameplate on the kiln for the rated amperage draw. For instance, a model J230 rated for 240 volts, Single Phase should draw 43.93 amps. If it is substantially less than the rated amperage draw and your voltage is within 5% of the rated voltage (for instance 230 volts for a 240 volt unit), then chances are the elements have changed in resistance. This will require element replacement. You can check element resistance by disconnecting the elements and checking the elements with an ohmmeter. See your instructions or check with factory for proper resistance.
  6. See more about how to diagnose a slow manual kiln.

Additional Actions to Take

  1. Look for the nameplate data. Plug the amperage and voltage labeled here into Ohm's Law to see what the resistance for the whole kiln should be. If the nameplate is missing you can email the factory to try and figure out what model it is. Measure the inside dimensions of the kiln, take whatever resistance readings you can, let us know whether it has Hi-Med-Low switches on infinite type switches and describe anything else you can about the kiln. An emailed digital picture can be very helpful.
  2. Measure the total resistance of the kiln. Unplug the kiln or turn off the power if you cannot unplug it when measuring resistance in these circuits. Now turn all switches to high, and turn the kiln-sitter on. Measure the ohms from the prongs on the main power cord–-from the two "hot" blades, not from the ground or neutral. If there is a reading, it should be within 9% of what was calculated with Ohm's Law. The resistance can only be lower than what the nameplate calculations would indicate if the wrong elements were installed in the kiln or the elements are so old that they are squashed into each corner all the way around the kiln. Look for overheated connection if low resistance continues for any length of time and replace elements immediately
  3. Measure the resistance of each branch circuit. Turn the switches OFF. The switches must be off or the meter will read all the branch circuits at once. Measure branch circuit resistance with the kiln power OFF from the two flat prongs (not the ground) of the plug-heads of each kiln section. On other kilns you want to determine how many elements are in each circuit and how the elements in each circuit connect together and to each circuit's power wires. Take the branch circuit resistance reading at the point where the power wires connect to the element(s).
  4. Determine series or parallel. Look to see if the elements are wired in series or in parallel with each other. Even in L&L's latest kilns you would still have to either take the element box off or look at the kiln's wiring diagram to determine this.
  5. Check individual element resistance. Try to get a single element's resistance reading by either calculating it if they are in parallel or by measuring it with the meter if they are in series. You may need to disconnect wires to isolate as much as possible of each element.
  6. Take a voltage reading in each branch circuit at either the element connection to the power wires or at the control box receptacles on later L&Ls. Measure the voltage at the main power supply. If there is a considerable voltage drop from the main power supply to the element connection to the power wires then there is a corrosion or connection problem. Badly corroded connections need to be replaced immediately. Both parts of the connection should be replaced at the same time. Check your plug and receptacle connections, especially the main power cord and receptacle.
  7. If the measured resistance is slightly more than 9% over the calculated resistance and this correlates with the problem (slow kiln), you should ideally replace all the elements, or at least those with readings that are too high. If you do not replace them all at once the kiln may heat unevenly (this is much less of problem with kilns having the zoned design with ungraded elements rather than with kilns that have graded elements.
  8. If all of the element resistances are fine but the resistance of the whole kiln is not, the problem must be in a branch circuit. 
  9. With the kiln on, run a voltage test on the receptacles or at the connections to each element in each branch circuit to see which is the bad one.
  10. With the power off, open the control panel and visually inspect the branch circuits. Check branch fuses if the kiln has them.
  11. Locate the two wires that begin the bad branch circuit from the bunch that come from L1 and L2 on the main power block.
  12. Follow those wires to where they connect to the first component in line, probably either a fuse block, a relay or a switch.
  13. With the power ON, and any kiln-sitters or switches on High (so that the elements would come on if they could), take a voltage reading at the point where these two wires connect to the first component in line. The reading normally should be the same as what it is at the main power block. If it is not, one of the wires between the main power block and the first component is bad and needs to be replaced.
  14. If there is voltage there then take another reading after the first component at the point where the two wires continue onto the next component or to the element connection. If there is voltage after the component then the component is working.
  15. To determine whether the contactor or the switch is bad, first follow the wires from the load side of the switch to the contactor. 
  16. With the power all on and the switch on high, take a voltage reading where the two wires from the switch to the contactor connect to the contactor. If these readings are the same, then the contactor is bad.
  17. If there is no voltage present, then follow those two wires back up to the load side of the switch and measure the voltage there. If the voltage readings are the same, then the contactor is bad.
  18. If there is no voltage present, then follow those two wires back up to the load side of the switch and measure the voltage there. If the voltage reading is the same, then one of the wires is bad.
  19. If there is no voltage present at the load side of the switch (power all on, switch on high, then be sure voltage is coming to the switch; if it is, then the switch is bad. Replace the switch and if the problem still persists then repeat the test; you will most likely have to replace the contactor as well.
  20. If there is no voltage after the first component in line and it is not a relay/contactor, then just replace it. If it is a fuse holder, just replace the fuse (usually a bad fuse means there is a short somewhere in the circuit). Use a "continuity" tester to test for bad fuses. Always check tightness of connections in a questionable circuit.
  21. If there is voltage after the first component then move along the circuit from the main power block towards the element connections, testing for voltage before and after every component until you isolate the problem. Voltage readings taken from between the elements (and from between resistors in general) give a reading that reflects voltage which is half the supply voltage with two elements in series, and either one-third or two-thirds the supply voltage with three elements in series (depending on which side of the middle element in the series the test lead is placed).
  1. Make sure you have programmed the kiln properly and it is supposed to be firing.
  2. Read the Operation instructions.
  3. Do a Program Review as soon as you start firing. (For DynaTrols - see this video)

Use cone packs in all sections (top, center, bottom) of the kiln and keep records of what happens.

  1. Unplug the kiln.
  2. Follow the instructions in the Assembly Instructions for removing the Control Box. (Click here for a list of all assembly instructions).
  3. Pack the control panel with cushioning material such as bubble wrap, balled-up newspaper or foam in a cardboard box and follow instructions from the factory or you local distributor about where to send it.

CAUTION: Do not send a control panel without calling first.

CAUTION: The controller contains electronic components which are sensitive to static electricity. Before handling the controller dissipate any static charge you may have by touching metal or a screw on the controller panel, the electrical box, the kiln lid, or some other grounded object.

 

This video shows how to remove a control panel on an Easy-Fire, School-Master or eQuadPro kiln for service.

  1. Dig out any loose particles with a small knife.
  2. Brush and vacuum the surface of the brick clean to remove any loose material or crumbling firebrick.
  3. Wet the brick surface lightly with clean fresh water. Use a paint brush or spray bottle (make sure there is no soap residue in the bottle).
  4. Apply a thin coat of brick cement all over the hole. This is defined as about 1/32" to 1/16" thick. Do this with your finger, a small brush, or a spatula.
  5. Fill hole with the special grout material. Apply grout with a spatula (like plaster). You can also use your finger. Push it into the hole. It is OK to let it be a rough surface or slightly larger than the hole it is filling.
  6. Let dry for 24 hours.
  7. Take some rough sandpaper and sand surface to even it out with the rest of the firebrick.
  8. Run the First Firing Cycle ( See first-firing.pdf in the Operation Section or see this search link).
  9. You can brush on brick facing afterward if you desire.
  1. Cut out an area around the brick chip with a small knife, saw or router. The hole that you make should have 90 degree angles so that a square or rectangular block will fit in the hole.
  2. Cut a piece of firebrick to fit into this cut out hole. The piece should be slightly smaller than the hole (by about 1/16" to 1/8").
  3. Both the hole and the brick piece should be brushed and vacuumed clean.
  4. Wet the surface lightly. (Both the hole and surface of the block that you are going to insert in the hole). Use a paint brush or spray bottle (make sure there is no soap residue in the bottle).
  5. Apply the Kiln Cement to the surface of the piece that you are going to put in the hole. Use only about 1/32" or 1/16" of cement.
  6. Insert cut piece of firebrick immediately and push into place so that it makes contact on all sides with the underlying firebrick.
  7. Let dry for 24 hours at minimum.
  8. Cut off and/or sand off excess brick and cement.
  9. Cover with Brick Facing and allow to dry for another 24 hours.
  10. Turn kiln onto low for 3 hours to dry totally.
  11. Run the First Firing Cycle (See first-firing.pdf in the Operation Section).

See this video:

The control board needs to be replaced if:

  1. The transformer is OK.
  2. You know you have voltage going to the control board but the control still shows no display.
  3. You know you have voltage going to the control board but there is no output form the control to the power relays (even if you have display). In this case the little transistors inside the control that regulate output are not functioning).
  1. Unplug kiln.
  2. Remove the control box and remove the insulation panel.
  3. Using needle nose pliers pull of the wires from the transformer. It can take significant force to remove the spade connectors.
  4. Unscrew the two nuts that hold the control transformer onto the panel and remove the transformer.
  5. Before installing the new transformer put the small jumper wire onto terminals #2 and #3 on the bottom row of terminals. Note the little numbers by the contacts.

  1. Remove the kiln sections.
  2. Take the old bottom of the stand.
  3. Put the new bottom on the stand.
  4. Relevel the kiln.
  5. Replace the kiln sections.

NOTE: You may want to experiment with using the old bottom as a secondary back-up bottom if it is not too badly damaged. Some find that having this extra insulation thickness helps firing times and bottom uniformity.

  1. Unplug kiln.
  2. Remove the four #6 screws that hold the control in place from the front face of the control panel.
  3. Remove the control box and remove the insulation panel.
  4. Pull of the spade connectors from all the connection points on the back of the control. Loosen the screws that hold down the thermocouple wires and pull out the wires from under the screw heads. It is OK to remove the screws if this is easier for you. First not where all the wires go. These are all clearly marked with color coding on the Wiring Diagram.
  5. Pull old control out. Put new control in and screw in place with the #6 mounting screws. Replace wires on proper connectors.
  6. Be careful to get the Red or Yellow of the thermocouple wires to match the colors painted on the control board.
  7. Double check that the proper color coded wire goes to the proper terminal (Orange = OUT, Purple = AC1, Green = CT, Gray = AC2).

This video shows how to replace a DynaTrol on an Easy-Fire kiln. The same principles apply to any kiln with a DynaTrol or Genesis control.

Parts

  1. See this page for the part.

WARNING IF YOU HAVE A TYPE S THERMOCOUPLE: WHEN REPLACING A DYNATROL: CHECK THE CONFIGURATION OF THIS REPLACEMENT CONTROL TO MAKE SURE YOU DON’T MELT YOUR KILN! See this for more information.

This video shows how to remove a control panel on an Easy-Fire, School-Master or eQuadPro kiln for service.

  1. Unplug kiln.
  2. Remove or hinge open the control box.
  3. Remove the Thermocouple Lead Wire from the Thermocouple.
  4. Unscrew the Thermocouple from the kiln.
  5. Remove Thermocouple.
  6. Install a new Thermocouple and screw in place.
  7. Replace Thermocouple Lead Wire and tighten. Be sure to get red matched to the MINUS (Negative) sign and the Yellow matched to the PLUS (Positive) sign.

See this video:

Running a paper test is a great way to troubleshoot your kiln. With just some scraps of paper and 5 minutes you can determine if you have any elements or relays that need replacing.

Despite it's usefulness, the paper test cannot compare to the information that you can get from a multimeter. It will only point you in the direction of a problem, not pinpoint it.

The Paper Test

  1. Start by folding up small strips of paper. You will need one paper per element in the kiln that you want to test.
  2. Turn off the kiln and unplug it (or at least shut it off at the circuit breaker/fused disconnect).
  3. Insert the paper scraps in between the coils of each element. It does not matter where along the element.
  4. Plug-in and turn on the kiln.
  5. Program for Fast Glaze to any cone (or turn manual switches on high).
  6. With the lid open, watch the paper scraps for smoking. (Do NOT reach into the kiln while it is on. Contact with the elements could cause electrocution and/or burns).
  7. After approximately 2 minutes, the paper should start to smoke. Wait another minute or so to give them all a chance to burn.
  8. Turn off the kiln and unplug it (or at least shut it off at the circuit breaker/fused disconnect).
  9. Use pliers, tweezers, etc. to remove the paper from the elements as they will still be very hot. Make sure to note which pieces burned and which, if any, did not.
  10. Vacuum or simply blow out any remaining ashes in the element holders.

Conclusions

Once you have your results, you can start to draw some conclusions. We will look at one section at a time. These are some potential results and causes. Keep in mind you might have any combination of these issues.

If the paper is not burnt in one element in a ring:

  1. The element is burnt out/broken and needs to be replaced.
  2. Your elements are wired incorrectly at the element terminal block.

If the paper is not burnt in all (2 or 3) elements in a ring:

  1. All elements in the ring are burnt out/broken and need replacing.
  2. Your relay for that section is burnt out and not working.
  3. One (or more) of the power wires to that ring is burnt or disconnected.
  4. Your controller is not sending the proper output to the relay. Test the controller.

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. Empty the kiln.
  2. Turn kiln on using a fast program such as FAST GLAZE (USr3) until elements are red.
  3. Open the door carefully and check if each of the elements are glowing with approximately the same brightness.
  4. This is an approximate method. The best thing to do is check the ohms on each element or circuit.

CAUTION: The power does not turn off when the lid is opened. Do NOT put your hand inside the kiln while it is on.

  1. Check your voltage at the receptacle or at your fused disconnect box. Check voltage at your panel and where the kiln is connected. Check the voltage when the kiln is firing and when it is not firing.
  2. Make sure no other large electrical appliances such as a clothes dryer or electric oven are on when you are operating your kiln.
  3. Find out from your local utility company when the end of the peak period of electrical use is.
  4. Check to see what the wire size of your circuit is. If it is very far (more than 50 feet) from your main circuit box then the wire size might need to be higher.

  • Power relays are one of the most important components in your kiln. They execute the will of the computer controller, giving power to the elements only when requested. These power relays are also mechanical switches which will wear out over time. Worn out relays can be the cause of slow or incomplete firings, error codes (E-1, E-d), etc. Other more obvious signs of relay failure are if a zone is lagging behind in temperature considerably or if you notice an entire ring of elements not heating/glowing. 
  • The surest way to test your relays is by using a multimeter to check input, output, and signal voltage. If you do not have access to a multimeter you can run a paper test, which will give you some indication of whether or not you have a relay out.

Process

  1. One way to check the relays (or bad elements) is to check the temperatures of each zone by pressing "1", "2" and "3" in sequence and recording the temperatures of each thermocouple at intervals over the length of the firing. If one zone is consistently firing at a lower temperature then you probably have either burned out elements or a bad relay.
  2. If the relay does not make a soft clicking noise when the kiln is turned on try turning the kiln off and on and then restarting the program.
  3. Remove panel.
  4. Set your multi-meter the approximately 24 volts AC. Check the voltage coming into the coil of the Power Relay. You can tell which wires these are because they will be the small wires coming from the control. This test will tell you if you are getting power to the relay coil which actuates the relay. Unless the relay is actuated by the control you will get no output from the power side of the relay.
  5. With panel plugged in and firing check output from Power Relay with your digital multi-meter. The meter should be set to the next highest voltage above 240 volts AC. Output should be approximately the rated voltage of the kiln when it is supposed to be calling for power to the elements.

CAUTION: LIVE ELECTRICITY IS INVOLVED WITH SOME OF THESE TESTS. This test should only be done by an experienced person familiar with electricity.

  1. Make sure power cord is plugged in.
  2. Reseat the plug. Pull it out of the receptacle and put it back it. This will reseat the connections.
  3. Also, sometimes the female socket and/or the male spades get oxidized (which can resist the flow of electricity). Reseating them can disturb this oxide layer.
  4. When you do this examine the plugs for any signs of burning or overheating. If the spades look oxidized you can rub them with steel wool to shine them.
  5. Make sure the plug is held firmly and that the springs inside the receptacle seem to be working.
  6. Look for any damage on the cord itself.
  7. Make sure the cord is not touching the kiln case.

CAUTION: This test should only be done by an experienced person familiar with electricity and its dangers.

  1. Carefully examine thermocouple tip. This is the exposed welded joint at the end of the thermocouple that is not covered up by the ceramic tube.
  2. To do this you will have to remove the thermocouple from its protection tube (if it is a kiln that has one of our protection tubes). You can do this with the kiln disconnected from power.
  3. Look for corrosion - especially if it severe. These thermocouple tips will oxidize and otherwise corrode over time. That is normal. There is some point, however, at which the corrosion affects the ability of the tip to work (thermocouples work by generating a small voltage at the tip caused by two different metals reacting to each other).
  4. Corroded thermocouple tip

  5. Make sure the two wires are securely joined. One of the things that can cause an intermittent problem is a bad weld. If the two wires touch each other (even if they are not welded) they may work temporarily. However, if the weld is not secure then the wires could separate when the kiln heats up and cause an intermittent failure.
  6. If the thermocouple tip looks healthy then test the control board.

  1. Unplug kiln or turn off circuit breaker if the kiln is wired direct to your power supply. If you can not physically be sure the power is disconnected (for instance is you see that the cord is unplugged you KNOW there is no power coming into the kiln) then check the voltage at the power connection pluck with your multi-meter.
  2. Open up the control panel. This will be a little different on each kiln series.
  3. Remove or open the panels that cover the element connections.
  4. Look at internal wiring.
  5. Images burned wires in a kiln

  6. Check the tightness of all connections. Do this by wiggling the connector to make sure nothing is loose.
  7. Make sure all wires are connected to their proper connection point. You may have to compare the kiln to the wiring diagram to be sure of this. This step would be particularly important if a wire has come loose.
  8. Specifically look at wires going from power connection block to the on/off switch, then to the control fuse, and finally to the control transformer.
  9. Make sure all wires inside control panel are connected.
  10. Look for any burned spots or deteriorating wire.
  11. Look for any short circuits. This might be caused by a wire losing its insulation and touching another component for instance. Typically if there are any short circuits there will be some evidence of a burn on the metal the wire touched.
  12. Look for dirt or foreign material. Some material can be an electrical conductor and could cause a short circuit. Clean out any dirt.
  13. Pull off and reseat all spade connector connections of power wires to remove oxides and ensure good connection.

CAUTION: Turn power off to kiln from the circuit breaker or unplug the kiln.

Fix lid seal if a bright red glow is visible around the seal when kiln is operating and/or excessive heat loss can be felt around seal.

  1. Rub seal high points down with sandpaper until no more than 1/16 of an inch gap is found at any point along seal.
  2. Check for unevenness in the gap that will cause an excessive heat loss.
  3. Replace lid if it is excessively cracked or worn or has holes in it. Replace lid.
  1. The control fuse is normally located on the side of the control box.
  2. Twist open the fuse holder and physically check the little fuse.
  3. If the fuse is blown then you will see the metal element inside is melted.
  4. Optionally, you can use your digital multi-meter to check continuity across the fuse.
  1. Make sure the circuit breaker or fused disconnect switch is turned on.
  2. If you have a circuit breaker flip it back and forth to make sure that it is really on. Some circuit breakers, if they have tripped, will not be obviously in a tripped position. By flipping it back and forth you will reset the circuit breaker.
  3. Check voltage of your power supply at the receptacle using your multi-meter set to the next highest AC voltage above 240 (typically this will be 600 volts but may be 250)
  4. Check fuses for voltage continuity. You can do this with your multi-meter.
  5. Make sure fuses or circuit breaker are/is the proper amperage and type. See your wiring diagram for the required fuse type.

CAUTION: This test should only be done by an experienced person familiar with electricity.

1. Check for voltage (12 volts DC) between the output contacts (AC1 & AC2 marked on the control board) ground (any green wire).

CAUTION: This test should only be done by an experienced person familiar with electricity.

  1. Check voltage across the top center tap and either of the two top taps.
  2. If there is power look for a bad connection between the power connection block and the transformer.
  1. With the power to the kiln off, open the control box carefully and make sure that nothing is touching any of the exposed wires.
  2. Turn the power back on.
  3. Locate the transformer. Most have 3 wires on the bottom of them- the center wire is actually a
    jumper wire connecting the two center terminals, and three wires on the
    top of it- all wires are on one side of the transformer.
  4. Use a digital multimeter to check transformer operation.
  5. Set your digital multi-meter to AC volts, the next setting higher than 240 volts AC (on a lot of meters this is 600).
  6. Check voltage across the top center tap and either of the two top taps.
  7. With the meter you should be able to read 240 or 208 volts AC on the outer two wires at the bottom of the transformer. (These power wires come from the toggle switch and the power block). If there is 240 or 208 volts there everything is good up to the transformer.
  8. Set the meter to read 24 volts AC and look for this on the outer two wires of the 3 wires at the top of the transformer. If there is no voltage there then the transformer itself is faulty and you need to replace the transformer.
  9. If there is no power go further back on the line and measure the voltage. Keep going until you find voltage.
  10. Look for the problem between the point with the voltage and the last point checked that had no voltage.
  11. Replace transformer if you are not getting proper voltage.
  12. If there is proper voltage there then the control is getting the correct incoming voltage and that the board itself is probably faulty. Replace the control.

CAUTION: This test should only be done by an experienced person familiar with electricity.

See this tutorial on how to use a multimeter.

See this video:

  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:

  1. Unplug kiln.
  2. Remove the control box and the insulation panel.
  3. Remove the wires to the relay.
  4. Remove the nuts from the studs that hold the relay in place. Remove old relay and replace with new one.
  5. Visually inspect the wire connectors. Do they look corroded or "cooked"? Are the wires frayed? Any corrosion on the wire itself? If any of this is questionable you should replace the appropriate wires.
  6. Reconnect all wires. Visually inspect to make sure the spade connectors are down as far as they can go and feel to see that they are tight (a gentle tug should not remove one). If they are loose for some reason remove the wire and slightly squeeze the spade connector with pliers to tighten it.

IMPORTANT: The slip on wire connectors cannot be loose or corroded. If there is a bad connection then heat will be generated and the component that they slip onto (relay, terminal strip, etc) may overheat and fail. If you squeeze the slip on terminal to make it tighter–be sure to squeeze it evenly so that one side is not tight and the other loose. If there are any doubts about the integrity of the wire or the connector replace the whole wire or harness.

 

How to check a relay in an Easy-Fire Kilns

  1. Similar in any L&L automatic kiln.
  2. Follow proper electrical safety practices.

Parts

  1. See this page for the 12 Volt 30 Amp relay we use for most kilns.
  2. See this page for the 240 Volt 30 Amp relay we use as a control relay for 480 volt kilns.
  3. See this page for all contactors and relays.

 

How to change a relay in an Easy-Fire Kilns

  1. Be sure to keep the wires on in the right sequence when changing a power or control relay in an Easy-Fire, Easy-Fire XT, School-Master or eQuad-Pro Kiln.
  2. The configuration is similar in a Jupiter panel or as control relay in a DaVinci, Hercules, or Easy-Load panel.
  3. Make sure kiln is unplugged or locked out and tagged out at the circuit breaker or fused disconnect switch when doing this maintenance.

Parts

  1. See this page for the 12 Volt 30 Amp relay we use for most kilns.
  2. See this page for the 240 Volt 30 Amp relay we use as a control relay for 480 volt kilns.
  3. See this page for all contactors and relays.
  1. Make sure peepholes are plugged with peephole plugs.
  2. Make sure hole for vent is proper. Check Vent-Sure instructions for proper hole sizes.
  3. If you are using a different brand of vent make sure it is the appropriate size for the kiln. Check with the vent manufacturer and tell them how many cubic feet are in the kiln.
  4. If the lid or bottom is cracked check to see if it seems to leaking much heat at high temperatures. Patch or replace if extreme.
  1. Plug Peepholes in the kiln to prevent drafts.
  1. Plug element holes if they are too large.
  2. Lightly stuff non-RCF ceramic fiber in the element holes from inside the kiln using a sharp tool like a very small screw driver.
  1. If uneven firing occurs persistently, distribute your load weight more evenly throughout the kiln or to match the firing characteristics of the kiln.
  2. If elements typically fire hot at the top of the kiln put more weight in the top to absorb that heat, and vice versa.
  3. The bottom shelf should be at least 1/2" to 1" above the floor of the kiln.
  4. Badly distributed load weight can also affect the firing rate of the kiln and lead to Error 1.

TIP: The longer square posts can be laid down on their sides to get a perfect amount of space under the bottom shelf.