Why does my digital kiln make a chattering noise? It used to make a clicking noise.
Digital kilns and some switch-operated kilns use electric relays to power the heating elements. To turn on the elements, the digital controller sends power to the relays. Inside each relay, the power from the controller charges an electromagnet, which closes electrical contacts that turn on the elements. (You may have experimented with electromagnets in high school science class.)
During normal operation, a relay makes a clicking noise every time its electromagnet brings the contacts together. (Mercury relays are silent, however, because they don’t use mechanical contacts.) To better understand how a relay works, take apart an old one you are replacing. You will find the electromagnet and the contacts.
Sometimes a relay makes a chattering instead of a clicking noise. This is usually because the wires inside the electromagnet have over-heated, burning the insulation on the wires and weakening the electromagnet. Since the magnet is no longer strong enough to pull the contacts tightly together, the contacts chatter instead of click.
Before you replace a chattering relay, check the wires connected to it. A loose connection can cause even a new relay to chatter. You can usually tighten loose connections to solve the problem.
Tony Rodriguez, a kiln technician with GSM Enterprises in San Antonio, told us recently that he was repairing a 120 volt kiln that used an infinite control switch and a relay. Shortly after he replaced a chattering relay, the new relay also began to chatter. After examining the wires between the switch and the relay, he discovered that one of the connections was loose. When he repaired the connection, the relay stopped chattering. Tony called to tell us about the repair so that we could share it with you.