Kiln problem - Paragon w/Sentry Xpress 3

[Tom White]

You said you can program the kiln. This pretty well rules out a bad controller board. You said you can get a temperature increase on the readout by touching the thermocouple. This indicates the thermocouple is good and working. That leaves the relay, the wiring delivering the current to the elements and the elements. When you enter a program and tell the kiln to run it do you hear the "click" as the relay closes for the first time? If not the relay is your prime suspect. If you hear the click when the program starts to run you will have to examine the wiring between the relay and the elements plus the elements themselves. Your first post mentioned partial operation, heating for a while then failing to heat. Now you have no heating at all. That sounds to me like a failure in the switchbox of a wire between the relay and the elements, failing at some point of connection. When a wire carrying current has a bad or loose connection it encounters more resistance to current flow at that point. This leads to localized heating at the point of poor connection which leads to oxidation of the wire and/or connector there which adds more resistance to current flow which leads to more heating at that point and on and on in a vicious circle until the resistance becomes enough to melt the wire in two at that point resulting in an open circuit which will not carry current to and through the elements. You will have to unplug the kiln from the electric supply, remove the cover from the switch box and examine the large diameter wires which run to the elements at the top and bottom of the kiln. Gently move them at each end to see if they are still connected and not burned off at the end. Also inspect the jumper wire between the top and the bottom element near the center of the height of the kiln wall if this model kiln has two elements wired in series with a jumper wire between the top and bottom element. I suspect you will find the end of one of these three wires burned off from a failed connection which heated the wire until it melted in two. The repair will be to replace that wire with the proper wire using the proper ends on it and perhaps replacing the connector to which that wire is attached if it is also damaged. Paragon can supply the right wire and/or connector if you provide them with the kiln model number, serial number and part number(s) from your controller manual.

If none of the wires in the switch box are loose you will have to test each element for continuity by touching the probes of an ohm meter or multimeter set to the lowest resistance or continuity range to see if it conducts current provided by the tester from one end of the element to the other. If the needle of an analog meter moves, the digital reading of a digital meter changes and stays stable or the contunuity tone from the meter sounds that element is not burned in two inside the kiln. Perform the same test on the second element, the jumper wire between the elements (if present) and the wires attached to the top and bottom of the elements and the other end of that wire. If all tests indicate continuity the problem lies elsewhere.

My money is on a burnt wire in the switch box, however an element burned in two can connect when cold then move and disconnect when hot producing your first condition but this is much less likely than an open connection in the switch box.

Best wishes,
Tom inTexas