What do I do if the kiln doesn't heat at all (manual kilns)?

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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 do I do if the kiln doesn't heat at all (manual kilns)?
  1. Check many of the same things in the above section on Automatic kilns - power supply, branch fuses, short circuits, cord, etc.

  2. Make sure the infinitely variable zone input switches are turned on (if included on your kiln). There is a "click" in the "off position at "12 O'clock". Full on is the "click" position just to the right of this (1 O'clock).
  3. Infinitely Variable Zone Input Switches may have failed.
  4. Check to see if Dawson Timer is set properly. (If it is at "0" the kiln will not fire)
  5. Check to see if the Dawson plunger is not pushed into place.

Additional Actions to Take

Check Circuit Breaker or Fuses
  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.

Check Control Fuse
  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.
Check if internal switches are bad

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.

Check internal wires
  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. Unplug kiln.
  3. Open up the control panel. This will be a little different on each kiln series.
  4. Remove or open the panels that cover the element connections.
  5. Look at internal wiring.
  6. 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.
  7. Make sure all wires inside control panel are connected.
  8. Look for any burned spots or deteriorating wire.
  9. Look for any short circuits. This might be caused by a wire loosing 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.
  10. Look for dirt or foreign material. Some material can be an electrical conductor and could cause a short circuit. Clean out any dirt.
  11. Check all power wires for firm connections.
  12. Pull off and reseat all spade connector connections of power wires to remove oxides and ensure good connection.
Check Power Relay
  1. One way to easily check relays is to look at the kiln elements through the peepholes when the kiln is firing. If you know your elements are OK after having done an ohm test and the elements are not glowing then you should suspect the relays.
  2. Another 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.
  3. 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.
  4. Remove panel.
  5. 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.
  6. 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.

See this video:

Checking Elements

EASY-FIRE, DURA-FIRE, EQUAD-PRO, LIBERTY-BELLE

  1. With all power OFF, pace the test leads of the multimeter of the each of two of the terminals marked 1 and 2, 3 and 4, or 5 and 6 on the element terminal strip. Compare the reading you get to the reading you get from the other element terminals. Also check against the wiring diagram for the ohms listing.

JUPITER, DAVINCI

  1. With all power OFF, pace the test leads of the multimeter of the two flat prongs of each section's jumper cord, one on each prong, OR on both connecting wires, at the connection points with the elements. Compare the reading you get to the reading you get from the other jumper cords or connecting wires. Also check against the wiring diagram for the ohms.

See this tutorial on how to use a multimeter.

Examine all wiring for short circuits, bad connections, and burned areas.
  1. Check the tightness of all connections. Do this by wiggling the connector to make sure it is not loose.
  2. Examine all connections for any sign of oxidation or discoloration.
  3. Examine all wires for signs that the wire may have burned.
  4. 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.
  5. Look for any place where a wire may have shorted against the metal case or a component.

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

Replacing 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:

Replacing Power Relay
  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.
  7. See this video.

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.

Wiring in the Kiln
  1. Unplug kiln.
  2. Trace wiring for missing or bad connections.
  3. Check wiring against wiring diagram.
  4. Check for corroded connectors or connectors that have frayed wires. Replace any such connectors.

Applies to these Kiln Series

Applies to these Old Kiln Series