Dawson Kiln Sitter

The Kiln Sitter and how it Works

A Kiln Sitter is a mechanical device which removes power to the heating elements once the proper kiln temperature has been reached. The user sets a small pyrometric cone onto the Kiln Sitter cone support. The cone you place onto the support is formulated to bend when the kiln reaches a certain temperature. You can use a specific cone that bends at a given temperature. When you turn the kiln on and the temperature rises, the cone will bend at its rated temperature. A rod that is laying on the cone pivots and causes a lever to drop, turing the kiln off.

What Kilns Use a Kiln Sitter?

Currently, Evenheat produces three series of kilns that include the Kiln Sitter as standard equipment: The Classic, TnB and Fyrematic series. Good Kilns produces the Blue and Red series kilns which include the Kiln Sitter. In each of these series the kilns contain controls which regulate and control the heat with the Kiln Sitter shutting off power to the elements at the proper time.

Does the Kiln Sitter Control the Heating?

No. The Kiln Sitter simply removes power from the heating elements when the proper temperature is achieved. It has no other function.

What precautions should I take?

One important thing to remember is that the kiln sitter system is not fool-proof. For that matter, the computerized kilns can also malfunction. You must never leave a kiln unattended while it is firing. Never leave the room nor sleep when the kiln is on. Loose wiring can cause a fire. Wiring may work its way loose over time because of heating/cooling. Check the connections once per year.

A kiln that does not shut off when it is supposed to can cause what is called a meltdown. All of the ceramic or glass items in your kiln litterally melt and stick to the kiln shelf causing everything, including the shelf, to have to be thrown away. Know when the kiln is supposed to shut off. If it does not shut off after one hour beyond when it was supposed to, turn it off manually.

These are the usual causes for an over-fire

The cone did not bend correctly because of its age or how it was stored or because it was otherwise defective
Something in the kiln fell into or blew apart and hit the cone, its support or rod or went into the tube that holds the rod, causing the mechanism to malfunction
The rod was not totally free to move, usually because there is a piece of bisque that went into the tube when something blew up in the kiln
The lever that drops was out of adjustment or alignment or could not move freely
Though not causing an over-fire, a late turn off could be the result usually of a broken heating element, or less often, a malfunctioning switch.

What is the Limit Timer For?

The Kiln Sitter contains a device known as a Limit Timer (round knob shown above on Kiln Sitter faceplate). The role of the limit timer is to remove power from the elements after a certain period of time. This is what may be called a "back up" in the event of Kiln Sitter failure. The limit timer should never remove power during normal operation. On some kilns the limit timer is an option.

Can I Use any Pyrometric Cone in the Kiln Sitter?

No. Only those cones designed for use in the Kiln Sitter should be used. These include the small Orton cones, which are available in different temperature bending varieties.