Sentry 2.0 controller

[drhender]

I have acquired a kiln that has a Sentry 2.0 controller that was initially built for working with glass.  I'd like to use it for firing cone 4-5 ceramics.   I loaded it up and then set it to run a cone 5 program,  It ran through the program and the controller seemed to work fine.  At the end, it cycled through "CPLT", "1044", "2166", and then "0100" .  My understanding is that the 2166 is the max temp.  However, when things cooled off and I got to handle the pieces, it was clear that the clay isn't truly fired.  If I wet a sponge and rub the edge, it looks like it's not much more than just air dry.  I can scratch into it with my thumbnail.

I have heard that some of the Sentry controllers that are installed on kilns meant for glass work have a max temp somewhere in the firmware settings.  I found what looks like that setting and it is set to 2300, so I don't think that's the issue here.

So my question is, what happened?  Did the kiln not get as hot as the display indicates?  Am I reading the display wrong?  Do I have a bad thermocoupler?  

Thanks, in advance, for any advice.

David.

[Bill Kielb]

I believe this is your manual (below). If so the safety temp is not programmable. Your kilns nameplate should relatively match as well so worth checking it’s designed maximum. The only thing That strikes me is the controller is set for an S type thermocouple and you have a type k installed. When this happens kilns generally under fire considerably. Worth checking I think. If this is a cone 5 rated kiln. Then maybe suited to cone 04 work really.

manual: https://paragonweb.com/wp-content/uploads/IM204_Sentry12ky_RH-CF_Manual_Oct2009.pdf

Edited August 17, 2022 by Bill Kielb

[neilestrick]

Interesting. If it's truly a glass kiln, then I wouldn't expect it to even be able to get to cone 5. What's the max temp rating on the kiln serial plate? Did you check on the kiln while it was firing-was it glowing hot inside at any point? Did you double check the program to make sure you set it to cone 5 and not cone 05?

The type S thermocouple is a possibility, but I rarely see them in glass kilns since type K tend to last forever at the low temps glass kilns fire to. Definitely check, though.

[drhender]

Ahh... I hadn't looked closely at the plate-- it states max temp is 1700F.  Does that mean there's nothing I can do to change it?  I know this same controller is used on ceramics kilns.  Is it the case that the elements just can't provide the heat to get to where I'd like it to go?

Edited August 17, 2022 by drhender
Added photo of nameplate

[Dick White]

I suspect the electric power of the kiln (7,200 watts/30 amps in a kiln <3 cu.ft) would go to cone 4-6 easily, but the controller is set at the factory to match the original intention for the kiln usage, i.e., glass slumping that goes only to 1700 degrees. There are secret ways to get into the controller settings known only to Paragon technicians when they are building a kiln.

[Bill Kielb]

3 hours ago, drhender said:

At the end, it cycled through "CPLT", "1044", "2166", and then "0100" .  My understanding is that the 2166 is the max temp.

2166 is logical for cone 5 and 1044 ought to be 10 hours and 44 minutes, “CPLT” means complete and no errors so it appears the controller thought it made it.  Max temp can be found in the “SFTY” setting p24 so theoretically the controller can go as high as that setting. But the piece severely under fired. I would still check to make sure type S is not errantly set (p 22) in the controller and it has a common type K. Apparently If someone hit the reset function the default is type R.  It’s my only thought on why it is displaying 2166 and complete. If the kiln is stamped 1700 degrees it may not ever make cone 5 though just because it’s very underpowered…… or did someone change the elements and it is drawing more amperage (30a)  / wattage (7200w) than the nameplate? Lots of questions……….

 

Edited August 17, 2022 by Bill Kielb

[neilestrick]

If this is the same as the other other Fusion 10 kilns I'm seeing on the interwebs, it has elements in the lid? If so, that's also going to mess things up, because your heat distribution won't be right if you try to put more than one layer of pots in it. I would also be very concerned about the lid element sagging badly if you fired it up to cone 5/6.

[drhender]

Good news!!  Based on @Bill Kielb, suggestion I looked into the thermocouple-- it has a metal sleeve, so I am assuming it's a k-type.  I double-checked the setting in the controller-- it was set to r-type.   I switched the setting to K and ran another cycle to see if that resolved the problem.  I monitored temp inside the kiln with a digital thermometer and after correcting the thermocouple setting, the digital thermometer readings were very close to those displayed on the controller.  When the cycle finished, the pottery appears to be fired as expected.  I didn't have any test cones to be more sure, but the pottery now rings like fired ceramic and not raw clay.

@neilestrick, your concern about elements in the lid are well headed.  The reason I acquired it is because the glass artist wasn't able to use it anymore for glasswork because the way the elements are installed in the lid makes it weak and over time, the lid has started to flex and crumble onto the glass.  The elements are also sagging a little.   I plan to rebuild the lid and leaving the elements out after the rebuild will make that job easier.  Should I move the elements into the side walls?  Right now, there's only two loops of  elements in the lowest ring of bricks in the walls.  

Thanks again to all for the help!

[Bill Kielb]

3 hours ago, drhender said:

The elements are also sagging a little.   I plan to rebuild the lid and leaving the elements out after the rebuild will make that job easier.  Should I move the elements into the side walls?  Right now, there's only two loops of  elements in the lowest ring of bricks in the walls.

First I would really suggest you figure out how many watts this thing has. The old 1700 degree nameplate sort off indicates it really ought not to go to cone 5/6. Next, you will need all that wattage to get there so if you remove 1/3 of your power it most likely for sure won’t make it. Last, for someone skilled in kiln service it would likely be possible to invert this kiln and have elements in the bottom so gravity aids in retaining the elements. This also requires a little knowledge in zoning and how kilns fire evenly. The top and bottom generally being the coolest with the greatest losses.

I would first figure out how many watts this thing has which will give you an indication of whether this can be used to cone 5/6 for any reasonable length of time. More importantly it may reveal any wiring and control deficiencies you presently have as a result of someone prior having changed the elements but not updating the data plate.

[neilestrick]

Everything Bill said.  Based on the 30 amp power rating, in theory it has enough power to get to cone 5/6, but those elements might not be the appropriate thickness for firing that hot- they may burn out quickly if they're a thin gauge meant for lower temps, regardless of the power draw. You could flip the lid and floor, but you'd still have a large percentage of the walls without elements, which will cause evenness issues if you try to put more than one layer of pots in it. Grooving wall bricks and adding and element there would be a very difficult undertaking. You could buy grooved bricks for it, but that could get expensive. Personally, I don't think it would be worth the amount of work needed to get this working well as a pottery kiln.

[drhender]

@neilestrick, @Bill Kielb, thanks for your time and advice.  

[Ben Eberle]

Bill took the words right out of my mouth: Don't go with lid mounted elements. Period. Full stop. Best reason why? Can anyone here name me an commercially available ceramic kiln that has that feature? Anyone? Anyone? Bueller?? The answer is nope....and for good reason. Love the idea of swapping the lid with the floor....that is a good idea, but you're still going to have heat distribution issues unless you get another element in the wall.

 

I'm really with Neil: I'd sell that kiln....and just get a kiln designed for ceramic use. Depending on size....oh, man...you should be able to find what you need for 3-500.00 pretty easily. Heck - see if you can find an old Paragon doll kiln and pop that Sentry on it. It's designed to run two element circuits, so you'll be set.