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Help with kiln not working


Jamesmdx1
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Hi 

I have a Duncan teacher plus kiln, DA820-2.  I haven’t used it in a long while and before that I may have fired about 10 times purchased new . It currently doesn’t heat. I plugged it in and turned it on and the green light is on ..,started heating then just quit heating with the light still illuminated. Relay is not clicking at all and i put a new relay in and still not heating  or clicking. Not sure what would be next to replace, any ideas on what could be the problem ? There is a 2 in 1 timer, kiln sitter and there is a 3 position switch and timer 

any ideas  Thank you 

jim

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first check all the power to make sure you have 240 v. The pilot light would seem to indicate that you do but checking all the usuals is prudent, so cord, plug, breaker ......

Beyond that my best guess is some of the contacts could have corroded while in storage so prudent to cycle all the switches, including the timer several times to see if that brings the kiln to life. This kiln uses an infinite switch I believe or perhaps a three way switch. Cycle it several times and see if the kiln will start on any setting. If so, the switch is likely corroded internally and will need replacement.

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thanks for the reply. I did check both legs of the outlet and there is 120v on each leg. It was stored in a climate controlled room in my home so it never was exposed to dampness or extreme temps. The kiln is in excellent like new condition so it surprising that it doesn't heat

I did cycle all the infinite switch , timer and 3 way switch, even tapping them with a screwdriver, but nothing.

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Looking at this old diagram is wearing me out. It’s extremely blurry! . Set the auto manual switch to manual and turn on high. This should bypass the 2 hr timer and hopefully your elements start. If they do not, then there are power relays to check if you are comfortable around electric. I would check they are powered and engaged if powered. The infinite switch appears to drives a power relay which turns on and off the elements. There is a pilot output on the infinite switch which could  provide a back probe are to confirm it is actually working. Aside from that a close look to confirm all the wiring is connected and intact. My second wild guess is a bad 240 v relay or power relay. Unfortunately I believe someone will need to go through this with a meter and find out which device(s) are causing an open circuit.

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My Skutt had a similar problem,  four contact buttons had develop resistance,  they needed to be cleaned up with some emery cloth.  My husband had to take apart the kiln sitter to reach them, he said this was a job for someone who has worked on kilns.  Your kiln doesn't sound like it has been used enough for that to happen but maybe lack of use has cause some corrosion.   Denice

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Hi thanks for all the reply’s 

I did change the relay but still doesn’t heat or even click. All of the connections inside to the switches and controllers are all tight and free from any corrosion or rust . I think have to check to see if there is power to the wires going to the relay. It has to be something not allowing power to the relay .. all the switches and controls are tight without any play .. not sure what it could be 

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16 minutes ago, Jamesmdx1 said:

Could it be the infinite switch ?  That’s the switch that you turn to hi fire ceramic or over glaze.  That has the most wires connected to it 

Yes it could and is probable.  There are videos on how to test.
Without power - switch off L1 to H1 = no connection, L2 to H2 = no connection. Switch turned to on L1 to H1 connected or zero ohms and L2 to H2 connected or zero ohms. There are several videos out there, they are the same switch as used in most electric ranges.

The wires will need to be removed to do this test to avoid reading the rest of the circuit though.

Edited by Bill Kielb
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Ok thank you I will check that out today or tomorrow when I get home

what is the function of the 2 in 1 timer and would that be something that could prevent the kiln from heating and is there a way to test that ?  I see the replacement cost is like $200-400 bucks for that part .

I might be getting ahead of myself but would this be a good time to convert my kiln to an electronic control. Not even sure if this can be done with this model and not even sure what electronic controller I would use .

thanks 

 

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Any electric kiln can be used with an external/wall mount digital control box. You plug the kiln power cord into the control box, manually set the kiln on high, and the controller will cycle the whole thing on and off to control the rate of climb. If you're handy with electrical wiring, you can wire the elements directly to the sitter and bypass all the switches and relays, and use the sitter as a backup shutoff for the digital control box.

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ok so I  tested the infinite switch with the meter and it seems to test ok.

What I did next was to switch the wires on the relay to the last set of prongs which are always hot, the ones that they should be on are the switched prongs that are energized when the relay is switched on. The new relay has 8 prongs and the old one had only 6. I called the company that i bought it from and they told me that. So normally i wouldnt use those last 2 prongs. so switching to those 2 hot prongs I was able to get the kiln to heat. So my question is what do you think would be preventing the relay from switching on? Would it be the 2 in 1 timer?

That part seems to be very expensive and I dont want to get it if I'm not sure .. how would I test that?

thanks

Edited by Jamesmdx1
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Everything that involves live electrical requires appropriate caution! Please be safe at all times.

Ah, yes this is that kiln. If you restore your power relay to the former normally open contacts  and you jump pins 2 and 3 on the  interval relay your kiln should turn on with the bottom elements always on and the top elements working on the infinite  switch. You can’t leave it this way for long as the bottom elements will run continuous.

This only confirms the interval timer is bad, which it most likely is. Now this is a two in one interval timer that had an on delay interval and interval variability as I recall. Not made anymore and superseded by 4300 model timers  in later models which were also scrapped. The design was sort of a bust and the economical remedy was to scrap much of this and go back to infinite switches. So in your case, you would scrap the power relay and interval timer and replace with one infinite switch for the bottom elements.

Operation of the kiln would be: turn on low for a period of time, then medium, then high at the end. The good old days when simple almost always worked!

Infinite switches are widely available as they have been used in electric stoves forever. Paragon actually provided a previous poster with a suggested wiring diagram for the conversion back to the future or back to the past actually. If you can confirm the timer is dead as above you should be able to call paragon and ask if they have an infinite switch solution for this.

They are pretty workable, but who knows with Covid. If none of that works PM me.

Edited by Bill Kielb
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Many kiln companies went through a period where they tried to increase automation of manual kilns with mechanical timer systems prior to the advent of digital controllers. The systems worked fine when they worked, but they were typically overly-complicated and a bear to diagnose and repair when they stopped working and the gains in ease of use weren't all that great.

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If I can find one of the 4300 timers would that work the same way as the timer that I have ? 
I would be willing to upgrade the kiln to an electronic controller. It’s a Duncan DA820-2. That would I guess eliminate he kiln sitter and the timer .   I would like to get one that would fit in the space of the kiln sitter if possible. It I don’t know what one would work with my kiln.  I’d rather not have the additional box on the wall 

thanks 

Edited by Jamesmdx1
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You can certainly do all that although if I intended to modernize I would retrofit a Bartlett v6CF at minimum or their new genesis. Footprint or interior real estate is likely not an issue but I am very comfortable with electrical retrofit including the thermodynamics of keeping the electronics cool. Finding a drop in that age is probably based on pictures. Regardless I would guess the work likely would be 500.00 and up. And when you are done, it’s still not technically tested and UL/CSA/Fm ...... approved.

My thought,  for the 25.00-50.00 bucks I  would add an infinite switch for bottom element control for immediate use and save up for a readymade plug in controller. The sitter can stay for safety. Just my thinking though.

Edited by Bill Kielb
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You can't just drop in a controller because the box isn't made for it. Olympic makes a retrofit that surface mounts on the box where the sitter currently sits, but the benefits of a wall mount are that the electronics stay cooler and last longer, and you could use it with a second kiln if you ever get one.

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1 hour ago, Jamesmdx1 said:

If I went for the Olympic retrofit surface controller it would bypass all the original electric switches and timers? And would be completely controlled by the new controller.  I know the wall mount ones require all the original electric components have to be functional 

With the Olympic you'd still have to wire the elements directly to the back of the controller and bypass the switches/relays/etc, since the switches/etc are between the controller and the elements. Same for the wall mount.

With the wall mount you have a few choices:

1. Wire the elements directly to the sitter and use the sitter as a safety backup. You just put in a cone that's one cone higher than what the controller is firing to. It's a great safety, but you'd still have to invest in cones.

2. Wire the elements directly to the sitter and just cram a piece of kiln shelf under the sitter rod so that it always stays on. This is what most of my customers do, so they don't have to mess with cones.

3. Wire the elements directly to the power cord. The problem here is that ideally you'll still need some sort of terminal block to make the connections between the power cord and elements, which the sitter does nicely. You could use hi temp wire nuts, but I'm not a big fan of wire nuts in kilns- they make for sloppy organization in the box and complicates using a meter to test connections. It's not all that difficult to install a terminal block, though, as it can just be bolted to the interior of the box.

So with either system you're going to have to do some re-wiring if you want to get rid of the switches/relays/etc.

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@Jamesmdx1 “Bill, does that 4300 timer work the same way as the timer I have ?”

It does not if I recall and I believe there are variations when ordering it with respect to voltage as well as timing.  If you are dead set on operating on an interval there are many digital programmable these days that you could configure to match. It has just never really turned out to be superior to plain old infinite switches and turning things up gradually.  I don’t remember exactly but for the first two hours I believe it cycles on one minute, then off one minute. After that, It might go to on all the time. Don’t remember exactly but a bit of a strange scheme.

Lots of economical timers that would connect pin 2 to 3  or basically power the relay on and emulate whatever interval you would like actually as well as process controllers with the addition of a thermocouple make this an economical automatic kiln with a kiln sitter safety. All available these days for 100.00 or less. The current relays have become obsolete in many ways, but their economical substitutions require a bit of learning.

The infinite switch to me is easy, effective and time tested.

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Edited by Bill Kielb
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12 minutes ago, neilestrick said:

 

3. Wire the elements directly to the power cord. The problem here is that ideally you'll still need some sort of terminal block to make the connections between the power cord and elements, which the sitter does nicely. Y

I have seen folks just move the line to the load screws and double up or install jumpers keeping the sitter as a terminal block. An ok idea when neatly done. Providing something else will turn off the kiln faithfully..

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