How to create an interlock that prevents the kiln from firing unless an external ventilation system in on?

A customer asks if he can interlock his automatic kiln so that it will not fire unless his ventilation system is on. How do you accomplish this?

  1. The basic concept is that you want to break the common wire that feeds the control and/or power relays of an L&L automatic kiln. (This gets more complicated with a manual kiln with a kiln sitter and this advice does not apply to manual kilns).
  2. You will find the common wire for the relay coils coming from the "CT" terminal on the DynaTrol.
  3. Just break that common wire with dry normally open contacts of a control relay. The amperage and voltage is very low (12 volts and a few amps at most).
  4. Control the coil of your vent control relay with an output from your ventilation system.
  5. That could be, for instance, a double-throw switch that operates a 120 volt coil or some other more sophisticated output from a sensor or perhaps an airflow switch that allows 120 volts or some other voltage to flow to your control relay.
  6. The control relay can be mounted in the L&L control panel or can be external to it.