jen-Ken glass kilns G, GS & GS-E Series are supplied with Infinite switch(es). These switches are marked LO 2 3 4 5 6 HI. Low will yield 7% to 20% power and HI will yield   100% power. The numbers in between will cause the element(s) to maintain the   temperature corresponding to that number. These switches are used in hundreds of different appliances because of their simple design and reliability.

       Example: If the kiln switch is on #4, the kiln will maintain a temperature relative to
       the power given for that setting. It will cycle the element on and off to maintain that
       temperature. The setting #4 cannot be given in degrees because of the varying
       voltages and the kiln sizes. A pyrometer and a log book will help you to determine
       and record the temperature and switch settings for your kiln.

Remember that LO is low power, HI is full power and the numbers in between will cycle on and off.

Cycling of an Infinite Switch

When an infinite switch is turned on, it will automatically cycle on and off, in the 2, 3, 4, 5, & 6 positions. This regulates the amount of power the elements receive. The cycling of the switch causes a clicking sound and occasionally a small spark within the switch as the contact is broken.

Low Position
This position should have the power on 10% to 30% of the time. As the switch is turned to higher numbers, it gradually increases the amount of time the switch is on and therefore gradually increases the amount of heat the elements generate.

#4 Position
                This position is midway between low and high. At this position the
                switch should be on about 50% to 60% of the time.

  #6.5 Position
                This position is just before the switch is in the "HI" indexing position. At
                this position the switch should be on about 70% of the time.

  High Position
                At this position the switch is on and will not cycle off. It will deliver full
                power to the elements continuously. Warning: Do Not Allow Kiln to
                Exceed 1800 °F Max Temperature

  What Causes Heating Variations

The voltage available to the kiln will affect the switch calibration. We assume that your kiln is receiving a full 120 or 240 volts. If the actual voltage is more than 120 or 240 volts, the amount of time on will be significantly decrease. This does not mean the switch is out of calibration, but that the switch is reacting to the voltage being applied to it. Low voltage will also affect the switch's performance, but in the opposite manner. The switch will be on more than is normal. This can cause the switch to be out of its set range percentages.

Slow Heating from One Kiln to Another:

Some customers find that one kiln may fire more slowly than another. A standard firing time to one customer may be too long for another. This can be related to kiln size and load, or to varying electric current. You should run a calibration test on your kiln when you first fire it.

Firing Test (actually 3 tests)

1. Turn your kiln on to the HI position and let it heat to 1000 degrees.  Mark the temperature down every 15 minutes.  When the kiln reaches 1000 degrees put the final time.  Now divide 1000 by the total time it took to reach that temperature.  This is the average temperature rise in degrees per minute.

2. Repeat the above test at postion 5.  Be sure the kiln has cooled down to room temperature before you start.

3. Repeat the above test at the LO position. Be sure the kiln has cooled down to room temperature before you start.

Remember: identical kilns can fire differently.

Pilot Light

All Jen-Ken G, GS & GS-E Series with infinite switches come with a power on light called a pilot light. It is a neon light that is very long-lasting. If the kiln is working properly, but the light is no longer working, it should be replaced. If the pilot light is not working, check the wiring for loose connections or for a bad switch.

Loading the Kiln

The kiln shelf needs to be placed on posts that rest on the bototm of the kiln. The posts allow heat and air to circulate around the shelf to uniformly heat the glass on the shelf. The posts should be a minimum of 1/2" high. One-inch posts are standard for most larger kilns. Taller posts can be used if the project requires more top heat, by putting the work closer to the lid elements.

It is not recommend that more than one shelf be used in a glass kiln during a firing. If small pieces such as jewelry are being fused then two shelves may be used if a third shelf is used as a baffle to redirect and absorb the heat from the lid element. This process has worked for many and may take trial and error to get the best spacing with the shelves and posts.