Duncan EA 820-2 Teacher Plus - rapid clicking/chattering noise

[Yvonne51]

I have a constant chattering noise when I start up my 40 yr old Duncan EA 820-2. I have just replaced all the elements, the relay, the switch and someone else replaced the Kiln Sitter for me.  I fired the kiln empty with 04 cone in the Kiln Sitter on the Hi Fire setting.  All the elements glowed red and the Kiln Sitter turned off the Kiln after only 1 hour 15 min. The cone slumped as it should.  I have 2 questions - 1.  Is the chattering sound normal?  if not - any idea as to what makes the chattering sound/how to fix it?

2. is my kiln firing too hot to quickly? 

I will attach photos of the new parts added to the kiln. Thank you for your help.

 

[Bill Kielb]

If you search the forum you will find lots about this generation of kilns. Firing too quickly is a common issue when one or both solid state timers stop functioning as intended. The end result is generally firing too fast. Unfortunately replacement of the solid state relays is often the fix but they are expensive if available at all. The fix is generally to install a second infinite switch and remove the timers from the kiln. Depending upon model the new infinite switch ( because of load)needs to power the line voltage relay which powers the lower elements I believe. It takes a bit of electrical proficiency for sure.

Once done the kiln is operated in a conventional manner turning up the power gradually as a manual kiln during the firing.

Edited May 24, 2023 by Bill Kielb

[neilestrick]

Sounds like a relay got stuck 'on' so the kiln climbed very quickly. 1.5 hours is at least 4 hours faster than it should fire. As Bill said, it's probably a problem with one of the timer relays at the bottom of the control box. Figuring out which one will take some doing with a meter, and you may or may not be able to find a replacement part. It looks like your kiln has two groups of elements? The easiest and least expensive solution is to pull out the timer relays and add another infinite switch so that you then have two switches, and each switch controls one section of the kiln. Post a pic of the serial plate of the kiln, and a pic of the entire element connection area.

[Yvonne51]

Attached are a photo of the serial plate and the element connection area.  Thanks for your help.

[Bill Kielb]

If I have your wiring diagram right, and you can hear the repeat cycle timer clicking …. The timer relay on the left I believe, likely good news with respect to replacing the timer. Please check the black relay in the center of the kiln that connects to the bottom elements. If it does not cycle on and off with the timer relay then this relay is bad. If it cycles but the elements just stay powered, it is likely fused inside. If you need to replace this, the coil is rated for 240v operation. It is not your typical relay that you would see in most of todays kilns, so careful with replacement and order a proper relay.

your diagram should be

https://eadn-wc04-7751283.nxedge.io/wp-content/uploads/W-EA-and-DA-820-2-41.pdf

[neilestrick]

If you can't figure out the timer relay situation or can't get parts, you can just add one more 15 amp infinite switch, do away with all the relays, and wire each element set to one of the switches. If it were me, I'd go ahead and replace the old switch, too, so you're starting fresh with matching switches. Any 240 volt, 15 amp infinite switch kit will work. I like Robert Shaw brand. Make sure it includes the knob, because many don't.

[Yvonne51]

Thank you Neil and Bill for all of your advice. I was able to purchase the Solid State Timers from Artisan Controls - as you noted, they were a little expensive ($78.00 each) but I was not confident in my ability to install another infinite switch and eliminated the relays.  The new Timers eliminated the clicking/chattering noise and now I can hear the timers cycling on and off  properly.  I really appreciate all of your help!